{"id":461,"date":"2021-12-17T21:45:35","date_gmt":"2021-12-17T21:45:35","guid":{"rendered":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/6-metamorphic-rocks\/"},"modified":"2022-05-18T14:11:27","modified_gmt":"2022-05-18T14:11:27","slug":"6-metamorphic-rocks","status":"publish","type":"chapter","link":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/6-metamorphic-rocks\/","title":{"raw":"6 Metamorphic Rocks","rendered":"6 Metamorphic Rocks"},"content":{"raw":"[caption id=\"attachment_3142\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/BCG3-scaled.jpg\"><img class=\"wp-image-3142 size-large\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/BCG3-scaled-1.jpg\" alt=\"The painted wall is a large cliff\" width=\"1024\" height=\"768\"><\/a> Painted Wall of Black Canyon of the Gunnison National Park, Colorado, made of 1.7 billion-year old gneiss intruded by younger pegmatites.[\/caption]\n<h1>6 Metamorphic Rocks<\/h1>\n<em>Contributing Author: Dr. Peter Davis, Pacific Lutheran University<\/em>\n\n<b>KEY CONCEPTS<\/b>\n<ul>\n \t<li>Describe the [pb_glossary id=\"1767\"]temperature[\/pb_glossary] and pressure conditions of the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] environment<\/li>\n \t<li>Identify and describe the three principal [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] agents<\/li>\n \t<li>Describe what [pb_glossary id=\"1998\"]recrystallization[\/pb_glossary] is and how it affects [pb_glossary id=\"1765\"]mineral[\/pb_glossary] crystals<\/li>\n \t<li>Explain what [pb_glossary id=\"2002\"]foliation[\/pb_glossary] is and how it results from directed pressure and [pb_glossary id=\"1998\"]recrystallization[\/pb_glossary]<\/li>\n \t<li>Explain the relationships among [pb_glossary id=\"2004\"]slate[\/pb_glossary], [pb_glossary id=\"2006\"]phyllite[\/pb_glossary], [pb_glossary id=\"2007\"]schist[\/pb_glossary], and [pb_glossary id=\"2010\"]gneiss[\/pb_glossary] in terms of metamorphic grade<\/li>\n \t<li>Define [pb_glossary id=\"2017\"]index mineral[\/pb_glossary]<\/li>\n \t<li>Explain how [pb_glossary id=\"2020\"]metamorphic facies[\/pb_glossary] relate to [pb_glossary id=\"1669\"]plate[\/pb_glossary] [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] processes<\/li>\n \t<li>Describe what a contact [pb_glossary id=\"2023\"]aureole[\/pb_glossary] is and how [pb_glossary id=\"2022\"]contact metamorphism[\/pb_glossary] affects surrounding rock<\/li>\n \t<li>Describe the role of [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] in forming [pb_glossary id=\"1765\"]mineral[\/pb_glossary] deposits and [pb_glossary id=\"2403\"]ore[\/pb_glossary] bodies<\/li>\n<\/ul>\n[caption id=\"attachment_2480\" align=\"alignright\" width=\"379\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Fig-6-1.jpg\"><img class=\"wp-image-46\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-300x278.jpg\" alt=\"The rock cycle shows how different rock groups are interconnected. Metamorphic rocks can come from adding heat and\/or pressure to other metamorphic rock or sedimentary or igneous rocks\" width=\"379\" height=\"352\"><\/a> Rock cycle showing the five materials (such as igneous rocks and sediment) and the processes by which one changes into another (such as weathering). (Source: Peter Davis)[\/caption]\n\n<strong>[pb_glossary id=\"1992\"]Metamorphic[\/pb_glossary] rocks<\/strong>, <em>meta-<\/em> meaning change and -<em>morphos<\/em>&nbsp;meaning form, is one of the three rock categories in the [pb_glossary id=\"1749\"]rock cycle[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/1-understanding-science\/\">Chapter 1<\/a>). [pb_glossary id=\"1762\"]Metamorphic rock[\/pb_glossary] material has been changed by [pb_glossary id=\"1767\"]temperature[\/pb_glossary], pressure, and\/or fluids. <span style=\"font-weight: 400\">The [pb_glossary id=\"1749\"]rock cycle[\/pb_glossary] shows that both [pb_glossary id=\"1753\"]igneous[\/pb_glossary] and sedimentary rocks can become [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks. And [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks themselves&nbsp; can be re-metamorphosed. <\/span>Because [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] is caused by [pb_glossary id=\"1654\"]plate tectonic[\/pb_glossary] motion, [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] provides geologists with a history book of how past [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] processes shaped our planet.\n<h2><span style=\"font-weight: 400\">6.1 Metamorphic Processes<\/span><\/h2>\n[pb_glossary id=\"1992\"]Metamorphism[\/pb_glossary] occurs when solid rock changes in [pb_glossary id=\"1909\"]composition[\/pb_glossary] and\/or [pb_glossary id=\"1997\"]texture[\/pb_glossary] without the [pb_glossary id=\"1765\"]mineral[\/pb_glossary] crystals melting, which is how [pb_glossary id=\"1753\"]igneous rock[\/pb_glossary] is generated. [pb_glossary id=\"1992\"]Metamorphic[\/pb_glossary] [pb_glossary id=\"2418\"]source rocks[\/pb_glossary], the rocks that experience the [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary], are called the [pb_glossary id=\"1766\"]parent rock[\/pb_glossary] or <strong>[pb_glossary id=\"1766\"]protolith[\/pb_glossary]<\/strong>, from <em>proto<\/em>- meaning first, and <em>lithos- <\/em>meaning rock. Most [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] processes take place deep underground, inside the earth\u2019s [pb_glossary id=\"1658\"]crust[\/pb_glossary]. During [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary], [pb_glossary id=\"1766\"]protolith[\/pb_glossary] chemistry is mildly changed by increased [pb_glossary id=\"1767\"]temperature[\/pb_glossary] (heat), a type of pressure called [pb_glossary id=\"1995\"]confining[\/pb_glossary] pressure, and\/or chemically reactive fluids. Rock [pb_glossary id=\"1997\"]texture[\/pb_glossary] is changed by heat, [pb_glossary id=\"1995\"]confining[\/pb_glossary] pressure, and a type of pressure called [pb_glossary id=\"1996\"]directed stress[\/pb_glossary].\n<h3><span style=\"font-weight: 400\">6.1.1&nbsp; Temperature (Heat) &nbsp;<\/span><\/h3>\n[pb_glossary id=\"1767\"]Temperature[\/pb_glossary] measures a substance\u2019s energy\u2014an increase in [pb_glossary id=\"1767\"]temperature[\/pb_glossary] represents an increase in energy. [pb_glossary id=\"1767\"]Temperature[\/pb_glossary] changes affect the chemical equilibrium or [pb_glossary id=\"1780\"]cation[\/pb_glossary] balance in [pb_glossary id=\"1765\"]minerals[\/pb_glossary]. At high temperatures atoms may vibrate so vigorously they jump from one position to another within the crystal lattice, which remains intact. In other words, this atom swapping can happen while the rock is still solid.\n\nThe temperatures of [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] lies in between surficial processes (as in [pb_glossary id=\"1761\"]sedimentary rock[\/pb_glossary]) and [pb_glossary id=\"1750\"]magma[\/pb_glossary] in the [pb_glossary id=\"1749\"]rock cycle[\/pb_glossary]. Heat-driven [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] begins at temperatures as cold as 200\u02daC, and can continue to occur at temperatures as high as 700\u00b0C-1,100\u00b0C. Higher temperatures would create [pb_glossary id=\"1750\"]magma[\/pb_glossary], and thus, would no longer be a [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] process.&nbsp;[pb_glossary id=\"1767\"]Temperature[\/pb_glossary] increases with increasing depth in the Earth along a [pb_glossary id=\"222\"]geothermal gradient[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>) and [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] records these depth-related [pb_glossary id=\"1767\"]temperature[\/pb_glossary] changes.\n<h3><span style=\"font-weight: 400\">6.1.2 Pressure<\/span><\/h3>\nPressure <span style=\"font-weight: 400\">is the force exerted over a unit area on a material. Like heat, pressure can affect the chemical equilibrium of [pb_glossary id=\"1765\"]minerals[\/pb_glossary] in a rock. The pressure that affects [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks can be grouped into [pb_glossary id=\"1995\"]confining[\/pb_glossary] pressure and [pb_glossary id=\"1996\"]directed stress[\/pb_glossary]. <strong>[pb_glossary id=\"1993\"]Stress[\/pb_glossary]<\/strong> is a scientific term indicating a&nbsp;force. <strong>[pb_glossary id=\"1994\"]Strain[\/pb_glossary]<\/strong> is the result of this [pb_glossary id=\"1993\"]stress[\/pb_glossary], including [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] changes within [pb_glossary id=\"1765\"]minerals[\/pb_glossary].<\/span>\n<h4><b>Confining Pressure<\/b><\/h4>\n[caption id=\"attachment_3148\" align=\"alignright\" width=\"450\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.1-02-Pressure-vs-Stress.png\"><img class=\"wp-image-432\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-300x252.png\" alt=\"Pressure is a state where all stresses on a body are equal. The magnitude of these balanced stresses increases with increasing depth within the earth. These stresses can not deform rocks other than to decrease their volume. Pressure is the term used becuase the concept of pressure is used in chemistry, which it the discipline of science used to understand the mineral reactions that occur within the rock. DIRECTED STRESSES s, s, One or more directions of stress are not equal in magnitude and or not in line with each other (non-coaxial). Unlike balanced stresses, the difference in these stresses can deform rocks within the earth.\" width=\"450\" height=\"378\"><\/a> Difference between pressure and stress and how they deform rocks. Pressure (or confining pressure) has equal stress (forces) in all directions and increases with depth under the Earth\u2019s surface. Under directed stress, some stress directions (forces) are stronger than others, and this can deform rocks. (Source: Peter Davis)[\/caption]\n\n<span style=\"font-weight: 400\">Pressure exerted on rocks under the surface&nbsp;is due to the simple fact that rocks lie on top of one another. When pressure is exerted from rocks above, it is balanced from below and sides, and is called <\/span><b>[pb_glossary id=\"1995\"]confining[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> or <\/span><b>[pb_glossary id=\"1995\"]lithostatic[\/pb_glossary] pressure<\/b><span style=\"font-weight: 400\">. [pb_glossary id=\"1995\"]Confining[\/pb_glossary] pressure has equal pressure on all sides (see figure) and is&nbsp;responsible for causing chemical reactions to occur just like heat. These chemical reactions will cause new [pb_glossary id=\"1765\"]minerals[\/pb_glossary] to form.&nbsp;<\/span>\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"1995\"]Confining[\/pb_glossary] pressure is measured in bars and ranges from 1 bar at sea level to around 10,000 bars at the base of the [pb_glossary id=\"1658\"]crust[\/pb_glossary]. &nbsp;For [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks, pressures range from a relatively low-pressure of 3,000 bars around 50,000 bars, which occurs around 15-35 kilometers below the surface.<\/span>\n<h4><b>Directed Stress<\/b><\/h4>\n[caption id=\"attachment_3150\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2_800px-P535973.jpg\"><img class=\"wp-image-433 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-300x225.jpg\" alt=\"Pebbles in quartzite deformed by directed stress\" width=\"300\" height=\"225\"><\/a> Pebbles (that used to be spherical or close to spherical) in quartzite deformed by directed stress[\/caption]\n\n<strong>[pb_glossary id=\"1996\"]Directed stress[\/pb_glossary]<\/strong>, also called differential or [pb_glossary id=\"1996\"]tectonic stress[\/pb_glossary], is an unequal balance of forces on a rock in one or more directions (see previous figure). Directed [pb_glossary id=\"1993\"]stresses[\/pb_glossary] are generated by the movement of lithospheric [pb_glossary id=\"1669\"]plates[\/pb_glossary]. [pb_glossary id=\"1993\"]Stress[\/pb_glossary] indicates a type of force acting on rock. [pb_glossary id=\"1994\"]Strain[\/pb_glossary] describes the resultant processes caused by [pb_glossary id=\"1993\"]stress[\/pb_glossary] and includes [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] changes in the [pb_glossary id=\"1765\"]minerals[\/pb_glossary]. In contrast to [pb_glossary id=\"1995\"]confining[\/pb_glossary] pressure, [pb_glossary id=\"1996\"]directed stress[\/pb_glossary] occurs at much lower pressures and does not generate chemical reactions that change [pb_glossary id=\"1765\"]mineral[\/pb_glossary] [pb_glossary id=\"1909\"]composition[\/pb_glossary] and atomic structure. Instead, [pb_glossary id=\"1996\"]directed stress[\/pb_glossary] modifies the [pb_glossary id=\"1766\"]parent rock[\/pb_glossary] at a mechanical level, changing the arrangement, size, and\/or shape of the [pb_glossary id=\"1765\"]mineral[\/pb_glossary] crystals. These crystalline changes create identifying textures, which is shown in the figure below comparing the [pb_glossary id=\"992\"]phaneritic[\/pb_glossary] [pb_glossary id=\"1997\"]texture[\/pb_glossary] of [pb_glossary id=\"1753\"]igneous[\/pb_glossary] [pb_glossary id=\"1014\"]granite[\/pb_glossary] with the [pb_glossary id=\"2002\"]foliated[\/pb_glossary] [pb_glossary id=\"1997\"]texture[\/pb_glossary] of [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] [pb_glossary id=\"2010\"]gneiss[\/pb_glossary].\n\n[caption id=\"attachment_3152\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.1-03-Granite-vs-Gneiss.jpg\"><img class=\"wp-image-434 size-large\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-1024x443.jpg\" alt=\"Two rocks with very similar colors. One is a granite and another is a gneiss that has aligned dark minerals.\" width=\"1024\" height=\"443\"><\/a> An igneous rock granite (left) and foliated high-temperature and high-pressure metamorphic rock gneiss (right) illustrating a metamorphic texture. (Source: Peter Davis)[\/caption]\n\nDirected [pb_glossary id=\"1993\"]stresses[\/pb_glossary] produce rock textures in many ways. Crystals are rotated, changing their orientation in space. Crystals can get fractured, reducing their [pb_glossary id=\"1906\"]grain size[\/pb_glossary]. Conversely, they may grow larger as atoms migrate. Crystal shapes also become deformed. These mechanical changes occur via <strong>[pb_glossary id=\"1998\"]recrystallization[\/pb_glossary]<\/strong>, which is when [pb_glossary id=\"1765\"]minerals[\/pb_glossary] [pb_glossary id=\"1893\"]dissolve[\/pb_glossary] from an area of rock experiencing high [pb_glossary id=\"1993\"]stress[\/pb_glossary] and [pb_glossary id=\"1785\"]precipitate[\/pb_glossary] or regrow in a location having lower [pb_glossary id=\"1993\"]stress[\/pb_glossary]. For example, [pb_glossary id=\"1998\"]recrystallization[\/pb_glossary] increases [pb_glossary id=\"1906\"]grain size[\/pb_glossary] much like adjacent soap bubbles coalesce to form larger ones. [pb_glossary id=\"1998\"]Recrystallization[\/pb_glossary] rearranges [pb_glossary id=\"1765\"]mineral[\/pb_glossary] crystals without fracturing the rock structure, deforming the rock like silly putty; these changes provide important clues to understanding the creation and movement of deep underground rock [pb_glossary id=\"2143\"]faults[\/pb_glossary].\n<h3><span style=\"font-weight: 400\">6.1.3 Fluids<\/span><\/h3>\nA third [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] agent is chemically reactive fluids that are expelled by crystallizing [pb_glossary id=\"1750\"]magma[\/pb_glossary] and created by [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] reactions. These reactive fluids are made of mostly water (H<sub>2<\/sub>O) and carbon dioxide (CO<sub>2<\/sub>), and smaller amounts of potassium (K), sodium (Na), iron (Fe), magnesium (Mg), calcium (Ca), and aluminum (Al). These fluids react with [pb_glossary id=\"1765\"]minerals[\/pb_glossary] in the [pb_glossary id=\"1766\"]protolith[\/pb_glossary], changing its chemical equilibrium and [pb_glossary id=\"1765\"]mineral[\/pb_glossary] [pb_glossary id=\"1909\"]composition[\/pb_glossary], in a process similar to the reactions driven by heat and pressure. In addition to using [pb_glossary id=\"1778\"]elements[\/pb_glossary] found in the [pb_glossary id=\"1766\"]protolith[\/pb_glossary], the chemical reaction may incorporate substances contributed by the fluids to create new [pb_glossary id=\"1765\"]minerals[\/pb_glossary]. In general, this style of [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary], in which fluids play an important role, is called <strong>[pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary]<\/strong> or [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] alteration. Water actively participates in chemical reactions and allows extra mobility of the components in [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] alteration.\n\nFluids-activated [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] is frequently involved in creating economically important [pb_glossary id=\"1765\"]mineral[\/pb_glossary] deposits that are located next to [pb_glossary id=\"1753\"]igneous[\/pb_glossary] intrusions or [pb_glossary id=\"1750\"]magma[\/pb_glossary] bodies. For example, the [pb_glossary id=\"2402\"]mining[\/pb_glossary] districts in the Cottonwood Canyons and [pb_glossary id=\"1765\"]Mineral[\/pb_glossary] [pb_glossary id=\"508\"]Basin[\/pb_glossary] of northern Utah produce valuable [pb_glossary id=\"2403\"]ores[\/pb_glossary] such as argentite (silver [pb_glossary id=\"973\"]sulfide[\/pb_glossary]), galena (lead [pb_glossary id=\"973\"]sulfide[\/pb_glossary]), and chalcopyrite (copper iron [pb_glossary id=\"973\"]sulfide[\/pb_glossary]), as well as the [pb_glossary id=\"976\"]native[\/pb_glossary] [pb_glossary id=\"1778\"]element[\/pb_glossary] gold. These [pb_glossary id=\"1765\"]mineral[\/pb_glossary] deposits were created from the interaction between a granitic intrusion called the Little Cottonwood Stock and [pb_glossary id=\"1023\"]country rock[\/pb_glossary] consisting of mostly [pb_glossary id=\"1929\"]limestone[\/pb_glossary] and dolostone. Hot, circulating fluids expelled by the crystallizing [pb_glossary id=\"1014\"]granite[\/pb_glossary] reacted with and [pb_glossary id=\"1893\"]dissolved[\/pb_glossary] the surrounding [pb_glossary id=\"1929\"]limestone[\/pb_glossary] and dolostone, precipitating out new [pb_glossary id=\"1765\"]minerals[\/pb_glossary] created by the chemical reaction. [pb_glossary id=\"1999\"]Hydrothermal[\/pb_glossary] alternation of [pb_glossary id=\"1008\"]mafic[\/pb_glossary] [pb_glossary id=\"1664\"]mantle[\/pb_glossary] rock, such as [pb_glossary id=\"1789\"]olivine[\/pb_glossary] and [pb_glossary id=\"1013\"]basalt[\/pb_glossary], creates the [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] <strong>[pb_glossary id=\"2001\"]serpentinite[\/pb_glossary]<\/strong>, a member of the serpentine subgroup of [pb_glossary id=\"1765\"]minerals[\/pb_glossary]. This [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] process happens at mid-ocean [pb_glossary id=\"1708\"]spreading centers[\/pb_glossary] where newly formed [pb_glossary id=\"1659\"]oceanic crust[\/pb_glossary] interacts with seawater.\n\n[caption id=\"attachment_2545\" align=\"alignright\" width=\"304\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/BlackSmoker.jpg\">&lt;img class=\"wp-image-2545\" title=\"By University of Washington; NOAA\/OAR\/OER. (NOAA Photo Library: expl2366) [<a href=\"\/\/creativecommons.org\/licenses\/by\/2.0&quot;\">CC BY 2.0<\/a> or Public domain], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AExpl2366_-_Flickr_-_NOAA_Photo_Library.jpg&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/BlackSmoker-233x300.jpg\" alt=\"There is a large build up of minerals around the vent\" width=\"304\" height=\"392\"&gt;<\/a> Black smoker hydrothermal vent with a colony of giant (6\u2019+) tube worms.[\/caption]Some [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] alterations remove [pb_glossary id=\"1778\"]elements[\/pb_glossary] from the [pb_glossary id=\"1766\"]parent rock[\/pb_glossary] rather than deposit them. This happens when seawater circulates down through [pb_glossary id=\"986\"]fractures[\/pb_glossary] in the fresh, still-hot [pb_glossary id=\"1013\"]basalt[\/pb_glossary], reacting with and removing [pb_glossary id=\"1765\"]mineral[\/pb_glossary] ions from it. The [pb_glossary id=\"1893\"]dissolved[\/pb_glossary] [pb_glossary id=\"1765\"]minerals[\/pb_glossary] are usually ions that do not fit snugly in the [pb_glossary id=\"1787\"]silicate[\/pb_glossary] crystal structure, such as copper. The [pb_glossary id=\"1765\"]mineral[\/pb_glossary]-laden water emerges from the sea floor via [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] vents called <strong>[pb_glossary id=\"2000\"]black smokers[\/pb_glossary]<\/strong>, named after the dark-colored precipitates produced when the hot [pb_glossary id=\"234\"]vent[\/pb_glossary] water meets cold seawater. (see Chapter 4, [pb_glossary id=\"1753\"]Igneous Rock[\/pb_glossary] and [pb_glossary id=\"228\"]Volcanic[\/pb_glossary] Processes) Ancient [pb_glossary id=\"2000\"]black smokers[\/pb_glossary] were an important source of copper [pb_glossary id=\"2403\"]ore[\/pb_glossary] for the inhabitants of Cyprus (Cypriots) as early as 4,000 BCE, and later by the Romans.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"37\"]\n\n[caption id=\"attachment_4000\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-435\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 6.1 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">6.2 Metamorphic textures <\/span><\/h2>\n<span style=\"font-weight: 400\">[pb_glossary id=\"1992\"]Metamorphic[\/pb_glossary] [pb_glossary id=\"1997\"]texture[\/pb_glossary] is the description of the shape and orientation of [pb_glossary id=\"1765\"]mineral[\/pb_glossary] grains in a [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary]. [pb_glossary id=\"1762\"]Metamorphic rock[\/pb_glossary] textures are [pb_glossary id=\"2002\"]foliated[\/pb_glossary], [pb_glossary id=\"2012\"]non-foliated[\/pb_glossary], or lineated are described below.<\/span>\n\n[caption id=\"attachment_3157\" align=\"aligncenter\" width=\"791\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MetaRx3.png\"><img class=\"wp-image-436 size-large\" title=\"(Source: Belinda Madsen) SLCC\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-791x1024.png\" alt=\"Table identifying the types of metamorphic rocks.\" width=\"791\" height=\"1024\"><\/a> Metamorphic rock identification table. (Source: Belinda Madsen)[\/caption]\n<h3><span style=\"font-weight: 400\">6.2.1 Foliation and Lineation<\/span><\/h3>\n<span style=\"font-weight: 400\"><strong>[pb_glossary id=\"2002\"]Foliation[\/pb_glossary]<\/strong> is a term used that describes [pb_glossary id=\"1765\"]minerals[\/pb_glossary] lined up in planes. Certain [pb_glossary id=\"1765\"]minerals[\/pb_glossary], most notably the [pb_glossary id=\"966\"]mica[\/pb_glossary] group, are mostly thin and planar by default. [pb_glossary id=\"2002\"]Foliated[\/pb_glossary] rocks typically appear as if the [pb_glossary id=\"1765\"]minerals[\/pb_glossary] are stacked like pages of a book, thus the use of the term \u2018folia\u2019, like a leaf<\/span><span style=\"font-weight: 400\">. Other [pb_glossary id=\"1765\"]minerals[\/pb_glossary], with hornblende being a good example, are longer in one direction, linear like a pencil or a needle, rather than a planar-shaped book. These linear objects can also be aligned within a rock. This is referred to as a <\/span><b>[pb_glossary id=\"2003\"]lineation[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. Linear crystals, such as hornblende, tourmaline, or stretched [pb_glossary id=\"967\"]quartz[\/pb_glossary] grains, can be arranged as part of a [pb_glossary id=\"2002\"]foliation[\/pb_glossary], a [pb_glossary id=\"2003\"]lineation[\/pb_glossary], or [pb_glossary id=\"2002\"]foliation[\/pb_glossary]\/[pb_glossary id=\"2003\"]lineation[\/pb_glossary] together. If they lie on a plane with [pb_glossary id=\"966\"]mica[\/pb_glossary], but with no common or preferred direction, this is [pb_glossary id=\"2002\"]foliation[\/pb_glossary]. If the [pb_glossary id=\"1765\"]minerals[\/pb_glossary] line up and point in a common direction, but with no planar fabric, this is [pb_glossary id=\"2003\"]lineation[\/pb_glossary]. When [pb_glossary id=\"1765\"]minerals[\/pb_glossary] lie on a plane AND point in a common direction; this is both [pb_glossary id=\"2002\"]foliation[\/pb_glossary] and [pb_glossary id=\"2003\"]lineation[\/pb_glossary]. &nbsp;<\/span>\n\n[caption id=\"attachment_3164\" align=\"aligncenter\" width=\"588\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-06-Lineation.png\"><img class=\"wp-image-437\" title=\"Source: Peter Davis, Pacific Lutheran University\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-300x162.png\" alt=\"Lineation is aligned linear features in a rock. An example in the figure is a bundle of aligned straws.\" width=\"588\" height=\"318\"><\/a> Example of lineation where minerals are aligned like a stack of straws or pencils. (Source: Peter Davis)[\/caption]\n\n[caption id=\"attachment_3165\" align=\"aligncenter\" width=\"563\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-05-Foliationlineation.jpg\"><img class=\"wp-image-438\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-300x113.jpg\" alt=\"Aligned tourmaline crystals in line with foliation. Foliation is the fine &quot;layers&quot; of the rock.\" width=\"563\" height=\"213\"><\/a> An example of foliation WITH lineation. (Source: Peter Davis)[\/caption]\n\n[caption id=\"attachment_3167\" align=\"aligncenter\" width=\"538\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-04-Foliation-without-lineation.png\"><img class=\"wp-image-439\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-300x222.png\" alt=\"Foliated surface displays non-lineated hornblende grains. A cross-section displays a cross section of foliated plagioclase and hornblende\" width=\"538\" height=\"399\"><\/a> An example of foliation WITHOUT lineation. (Source: Peter Davis)[\/caption]\n\n[pb_glossary id=\"2002\"]Foliated[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks are named based on the style of their foliations. Each rock name has a specific [pb_glossary id=\"1997\"]texture [\/pb_glossary] that defines and distinguishes it, with their descriptions listed below.\n\n<b>[pb_glossary id=\"2004\"]Slate[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> is a fine-grained [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] that exhibits a [pb_glossary id=\"2002\"]foliation[\/pb_glossary] called <\/span><b>[pb_glossary id=\"2005\"]slaty cleavage[\/pb_glossary] <\/b><span style=\"font-weight: 400\">that is the flat orientation of the small platy crystals of [pb_glossary id=\"966\"]mica[\/pb_glossary] and chlorite forming perpendicular to the direction of [pb_glossary id=\"1993\"]stress[\/pb_glossary]<\/span><i><span style=\"font-weight: 400\">.&nbsp;<\/span><\/i><span style=\"font-weight: 400\">The [pb_glossary id=\"1765\"]minerals[\/pb_glossary] in [pb_glossary id=\"2004\"]slate[\/pb_glossary] are too small to see with the unaided eye. The thin layers in [pb_glossary id=\"2004\"]slate[\/pb_glossary] may resemble sedimentary [pb_glossary id=\"1935\"]bedding[\/pb_glossary], but they are a result of [pb_glossary id=\"1996\"]directed stress[\/pb_glossary] and may lie at angles to the original [pb_glossary id=\"1935\"]strata[\/pb_glossary]. In fact, original sedimentary layering may be partially or completely obscured by the [pb_glossary id=\"2002\"]foliation[\/pb_glossary]. Thin slabs of [pb_glossary id=\"2004\"]slate[\/pb_glossary] are often used as a building material for roofs and tiles.<\/span>\n\n[caption id=\"attachment_3169\" align=\"aligncenter\" width=\"383\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-Ehemaliger_Schiefertagebau_am_Brand.jpg\">&lt;img class=\"wp-image-3169\" title=\"By Uta Baumfelder at de.wikipedia (Own work) [Public domain], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AEhemaliger_Schiefertagebau_am_Brand.JPG&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-Ehemaliger_Schiefertagebau_am_Brand-300x225.jpg\" alt=\"Rock breaking along flat even planes.\" width=\"383\" height=\"287\"&gt;<\/a> Slate mine in Germany cleavage.[\/caption]\n\n[caption id=\"attachment_3171\" align=\"aligncenter\" width=\"420\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-07-Foliation-vs-bedding.jpg\"><img class=\"wp-image-440\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-300x200.jpg\" alt=\"Foliation is caused by metamorphism. Bedding is a result of sedimentary processes. They do not have to align.\" width=\"420\" height=\"280\"><\/a> Foliation vs. bedding. Foliation is caused by metamorphism. Bedding is a result of sedimentary processes. They do not have to align. (Source: Peter Davis)[\/caption]\n\n[caption id=\"attachment_3174\" align=\"alignright\" width=\"377\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-10-Phyllite-with-fold-scaled.jpg\"><img class=\"wp-image-3174\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-10-Phyllite-with-fold-scaled-1.jpg\" alt=\"A foliated rock with a slight sheen.\" width=\"377\" height=\"283\"><\/a> Phyllite with a small fold. (Source: Peter Davis)[\/caption]\n\n<b>[pb_glossary id=\"2006\"]Phyllite[\/pb_glossary] <\/b><span style=\"font-weight: 400\">is a [pb_glossary id=\"2002\"]foliated[\/pb_glossary] [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] in which platy [pb_glossary id=\"1765\"]minerals[\/pb_glossary] have grown larger and the surface of the [pb_glossary id=\"2002\"]foliation[\/pb_glossary] shows a sheen from light reflecting from the grains, perhaps even a wavy appearance, called crenulations<\/span><span style=\"font-weight: 400\">. Similar to [pb_glossary id=\"2006\"]phyllite[\/pb_glossary] but with even larger grains is the [pb_glossary id=\"2002\"]foliated[\/pb_glossary] [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] <\/span><b>[pb_glossary id=\"2007\"]schist[\/pb_glossary]<\/b><span style=\"font-weight: 400\">, which has large platy grains visible as individual crystals. Common [pb_glossary id=\"1765\"]minerals[\/pb_glossary] are [pb_glossary id=\"966\"]muscovite[\/pb_glossary], [pb_glossary id=\"966\"]biotite[\/pb_glossary], and porphyroblasts of garnets. A porphyroblast is a large crystal of a particular [pb_glossary id=\"1765\"]mineral[\/pb_glossary] surrounded by small grains. <\/span><b>[pb_glossary id=\"2008\"]Schistosity[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> is a textural description of [pb_glossary id=\"2002\"]foliation[\/pb_glossary] created by the parallel alignment of platy visible grains. Some schists are named for their [pb_glossary id=\"1765\"]minerals[\/pb_glossary] such as [pb_glossary id=\"966\"]mica[\/pb_glossary] [pb_glossary id=\"2007\"]schist[\/pb_glossary] (mostly micas), garnet [pb_glossary id=\"2007\"]schist[\/pb_glossary] ([pb_glossary id=\"966\"]mica[\/pb_glossary] [pb_glossary id=\"2007\"]schist[\/pb_glossary] with garnets), and staurolite [pb_glossary id=\"2007\"]schist[\/pb_glossary] ([pb_glossary id=\"966\"]mica[\/pb_glossary] schists with staurolite).<\/span>\n\n&nbsp;\n\n[caption id=\"attachment_3176\" align=\"aligncenter\" width=\"413\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-Schist_detail-e1492392805920.jpg\"><img class=\"wp-image-442\" title=\"Source: By Michael C. Rygel (Own work) [CC BY-SA 3.0 (http:\/\/creativecommons.org\/licenses\/by-sa\/3.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-300x184.jpg\" alt=\"Schist is a scalely looking foliated metamorphic rock.\" width=\"413\" height=\"253\"><\/a> Schist[\/caption]\n\n[caption id=\"attachment_3177\" align=\"aligncenter\" width=\"420\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-11-Muscovite-schist.jpg\"><img class=\"wp-image-443\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-300x165.jpg\" alt=\"Shiny foliated rock with small crystals of red faceted garnet among the foliated micas.\" width=\"420\" height=\"230\"><\/a> Garnet staurolite muscovite schist. (Source: Peter Davis)[\/caption]\n\n[caption id=\"attachment_3179\" align=\"alignleft\" width=\"354\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2_Gneiss.jpg\">&lt;img class=\"wp-image-3179\" title=\"By No machine-readable author provided. Siim assumed (based on copyright claims). [<a href=\"\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a> or <a href=\"\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AGneiss.jpg&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2_Gneiss-300x181.jpg\" alt=\"Alternating bands of light and dark minerals.\" width=\"354\" height=\"213\"&gt;<\/a> Gneiss[\/caption]&nbsp;\n\n<b>[pb_glossary id=\"2009\"]Gneissic banding[\/pb_glossary]&nbsp;<\/b><span style=\"font-weight: 400\">is a [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] [pb_glossary id=\"2002\"]foliation[\/pb_glossary]<\/span> <span style=\"font-weight: 400\">in which visible [pb_glossary id=\"1787\"]silicate[\/pb_glossary] [pb_glossary id=\"1765\"]minerals[\/pb_glossary] separate into dark and light [pb_glossary id=\"2009\"]bands[\/pb_glossary] or lineations. These grains tend to be coarse and often folded. A rock with this [pb_glossary id=\"1997\"]texture[\/pb_glossary] is called <\/span><b>[pb_glossary id=\"2010\"]gneiss[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. Since gneisses form at the highest temperatures and pressures, some [pb_glossary id=\"224\"]partial melting[\/pb_glossary] may occur. This partially melted rock is a transition between [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] and [pb_glossary id=\"1753\"]igneous[\/pb_glossary] rocks called a <\/span><b>[pb_glossary id=\"2011\"]migmatite[\/pb_glossary]<\/b><b>.<\/b>\n\n[caption id=\"attachment_2482\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/06.2-15-Mt-Blaca-Migmatite-1.jpg\"><img class=\"size-medium wp-image-48\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-300x225.jpg\" alt=\"Swirling bands of light and dark minerals.\" width=\"300\" height=\"225\"><\/a> Migmatite, a rock which was partially molten. (Source: Peter Davis)[\/caption]\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"2011\"]Migmatites[\/pb_glossary] appear as dark and light [pb_glossary id=\"2009\"]banded[\/pb_glossary] [pb_glossary id=\"2010\"]gneiss[\/pb_glossary] that may be swirled or twisted some since some [pb_glossary id=\"1765\"]minerals[\/pb_glossary] started to melt. Thin accumulations of light colored rock layers can occur in a darker rock that are parallel to each other, or even cut across the [pb_glossary id=\"2010\"]gneissic[\/pb_glossary] [pb_glossary id=\"2002\"]foliation[\/pb_glossary]. The lighter colored layers are interpreted to be the result of the separation of a [pb_glossary id=\"1006\"]felsic[\/pb_glossary] [pb_glossary id=\"1753\"]igneous[\/pb_glossary] melt from the adjacent highly metamorphosed darker layers, or injection of a [pb_glossary id=\"1006\"]felsic[\/pb_glossary] melt from some distance away. <\/span>\n<h3><span style=\"font-weight: 400\">6.2.2 Non-foliated<\/span><\/h3>\n[caption id=\"attachment_3185\" align=\"aligncenter\" width=\"413\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-21-Marble-scaled.jpg\"><img class=\"wp-image-3185\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-21-Marble-scaled-1.jpg\" alt=\"pink crystallized rock with interlocking crystals\" width=\"413\" height=\"300\"><\/a> Marble (Source: Peter Davis)[\/caption]\n\n[caption id=\"attachment_3188\" align=\"aligncenter\" width=\"420\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-20-Baraboo.jpg\"><img class=\"wp-image-445\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-300x275.jpg\" alt=\"Crystallized rock with interlocking crystals.\" width=\"420\" height=\"385\"><\/a> Baraboo Quartzite[\/caption]\n\n<b>[pb_glossary id=\"2012\"]Non-foliated[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> textures do not have lineations, foliations, or other alignments of [pb_glossary id=\"1765\"]mineral[\/pb_glossary] grains. [pb_glossary id=\"2012\"]Non-foliated[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks are typically [pb_glossary id=\"1909\"]composed[\/pb_glossary] of just one [pb_glossary id=\"1765\"]mineral[\/pb_glossary], and therefore, usually show the effects of [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] with [pb_glossary id=\"1998\"]recrystallization[\/pb_glossary] in which crystals grow together, but with no preferred direction. The two most common examples of [pb_glossary id=\"2012\"]non-foliated[\/pb_glossary] rocks are [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] and [pb_glossary id=\"2014\"]marble[\/pb_glossary]. <\/span><b>[pb_glossary id=\"2013\"]Quartzite[\/pb_glossary] <\/b><span style=\"font-weight: 400\">is a [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary] from the [pb_glossary id=\"1766\"]protolith[\/pb_glossary] [pb_glossary id=\"1912\"]sandstone[\/pb_glossary]. In [pb_glossary id=\"2013\"]quartzites[\/pb_glossary], the [pb_glossary id=\"967\"]quartz[\/pb_glossary] grains from the original [pb_glossary id=\"1912\"]sandstone[\/pb_glossary] are enlarged and interlocked by [pb_glossary id=\"1998\"]recrystallization[\/pb_glossary]. A defining characteristic for distinguishing [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] from [pb_glossary id=\"1912\"]sandstone[\/pb_glossary] is that when broken with a rock hammer, the [pb_glossary id=\"967\"]quartz[\/pb_glossary] crystals break across the grains. In a [pb_glossary id=\"1912\"]sandstone[\/pb_glossary], only a thin [pb_glossary id=\"1765\"]mineral[\/pb_glossary] cement holds the grains together, meaning that a broken piece of [pb_glossary id=\"1912\"]sandstone[\/pb_glossary] will leave the grains intact. Because most [pb_glossary id=\"1912\"]sandstones[\/pb_glossary] are rich in [pb_glossary id=\"967\"]quartz[\/pb_glossary], and [pb_glossary id=\"967\"]quartz[\/pb_glossary] is a mechanically and chemically durable substance, [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] is very hard and resistant to [pb_glossary id=\"1754\"]weathering[\/pb_glossary].<\/span>\n\n<b>[pb_glossary id=\"2014\"]Marble[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> is metamorphosed [pb_glossary id=\"1929\"]limestone[\/pb_glossary] (or dolostone) [pb_glossary id=\"1909\"]composed[\/pb_glossary] of [pb_glossary id=\"970\"]calcite[\/pb_glossary] (or dolomite). [pb_glossary id=\"1998\"]Recrystallization[\/pb_glossary] typically generates larger interlocking crystals of [pb_glossary id=\"970\"]calcite[\/pb_glossary] or dolomite. [pb_glossary id=\"2014\"]Marble[\/pb_glossary] and [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] often look similar, but these [pb_glossary id=\"1765\"]minerals[\/pb_glossary] are considerably softer than [pb_glossary id=\"967\"]quartz[\/pb_glossary]. Another way to distinguish [pb_glossary id=\"2014\"]marble[\/pb_glossary] from [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] is with a drop of dilute hydrochloric acid. [pb_glossary id=\"2014\"]Marble[\/pb_glossary] will effervesce (fizz) if it is made of [pb_glossary id=\"970\"]calcite[\/pb_glossary].<\/span>\n\n<span style=\"font-weight: 400\">A third [pb_glossary id=\"2012\"]non-foliated[\/pb_glossary] rock is <\/span><b>[pb_glossary id=\"2015\"]hornfels[\/pb_glossary] <\/b><span style=\"font-weight: 400\">identified by its dense, fine grained, hard, blocky or splintery [pb_glossary id=\"1997\"]texture[\/pb_glossary] [pb_glossary id=\"1909\"]composed[\/pb_glossary] of several [pb_glossary id=\"1787\"]silicate[\/pb_glossary] [pb_glossary id=\"1765\"]minerals[\/pb_glossary]. Crystals in [pb_glossary id=\"2015\"]hornfels[\/pb_glossary] grow smaller with [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary], and become so small that specialized study is required to identify them. These are common around [pb_glossary id=\"991\"]intrusive[\/pb_glossary] [pb_glossary id=\"1753\"]igneous[\/pb_glossary] bodies and<\/span><span style=\"font-weight: 400\">&nbsp;are hard to identify. The [pb_glossary id=\"1766\"]protolith[\/pb_glossary] of [pb_glossary id=\"2015\"]hornfels[\/pb_glossary] can be even harder to distinguish, which can be anything from [pb_glossary id=\"1915\"]mudstone[\/pb_glossary] to [pb_glossary id=\"1013\"]basalt[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_3191\" align=\"aligncenter\" width=\"413\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sample_of_Quartzite-e1493780752118.jpg\">&lt;img class=\"wp-image-3191\" title=\"By Manishwiki15 (Own work) [<a href=\"\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;\">CC BY-SA 3.0<\/a>], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3ASample_of_Quartzite.JPG&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sample_of_Quartzite-e1493780752118-300x210.jpg\" alt=\"Interlocking quartz grains in a quartzite.\" width=\"413\" height=\"289\"&gt;<\/a> Macro view of quartzite. Note the interconnectedness of the grains.[\/caption][caption id=\"attachment_3192\" align=\"aligncenter\" width=\"420\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/640px-CoralPinkSandDunesSand.jpg\">&lt;img class=\"wp-image-3192\" title=\"By Wilson44691 (Own work) [Public domain], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3ACoralPinkSandDunesSand.JPG&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/640px-CoralPinkSandDunesSand-300x225.jpg\" alt=\"Undeformed quartz grains do not interlock.\" width=\"420\" height=\"315\"&gt;<\/a> Unmetamorphosed, unconsolidated sand grains have space between the grains.[\/caption]\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"38\"]\n\n[caption id=\"attachment_4001\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-446\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 6.2 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">6.3 Metamorphic Grade<\/span><\/h2>\n[caption id=\"attachment_3194\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4_Garnet_Mica_Schist_Syros_Greece.jpg\"><img class=\"wp-image-447 size-medium\" title=\"By Graeme Churchard (GOC53) http:\/\/www.flickr.com\/people\/graeme\/ [CC BY 2.0 (http:\/\/creativecommons.org\/licenses\/by\/2.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece-300x225.jpg\" alt=\"Large weathered garnet crystals in a matrix of platy micas. The garnets are round-shaped with octagonal sides.\" width=\"300\" height=\"225\"><\/a> Garnet schist.[\/caption][pb_glossary id=\"1992\"]Metamorphic[\/pb_glossary] [pb_glossary id=\"2016\"]grade[\/pb_glossary] refers to the range of [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] change a rock undergoes, progressing from low (little [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] change) [pb_glossary id=\"2016\"]grade[\/pb_glossary] to high (significant metamorphic change) grade. Low-[pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] begins at temperatures and pressures just above [pb_glossary id=\"1761\"]sedimentary rock[\/pb_glossary] conditions. The sequence [pb_glossary id=\"2004\"]slate[\/pb_glossary]\u2192[pb_glossary id=\"2006\"]phyllite[\/pb_glossary]\u2192[pb_glossary id=\"2007\"]schist[\/pb_glossary]\u2192[pb_glossary id=\"2010\"]gneiss[\/pb_glossary] illustrates an increasing [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] [pb_glossary id=\"2016\"]grade[\/pb_glossary].\n\nGeologists use <strong>[pb_glossary id=\"2017\"]index minerals[\/pb_glossary]<\/strong> that form at certain temperatures and pressures to identify [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] [pb_glossary id=\"2016\"]grade[\/pb_glossary]. These [pb_glossary id=\"2017\"]index minerals[\/pb_glossary] also provide important clues to a rock\u2019s sedimentary [pb_glossary id=\"1766\"]protolith[\/pb_glossary] and the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] conditions that created it. Chlorite, [pb_glossary id=\"966\"]muscovite[\/pb_glossary], [pb_glossary id=\"966\"]biotite[\/pb_glossary], garnet, and staurolite are [pb_glossary id=\"2017\"]index minerals[\/pb_glossary] representing a respective sequence of low-to-high [pb_glossary id=\"2016\"]grade[\/pb_glossary] rock. The figure shows a <strong>[pb_glossary id=\"2019\"]phase diagram[\/pb_glossary]<\/strong> of three [pb_glossary id=\"2017\"]index minerals[\/pb_glossary]\u2014sillimanite, kyanite, and andalusite\u2014with the same chemical formula (Al<sub>2<\/sub>SiO<sub>5<\/sub>) but having different crystal structures (<strong>[pb_glossary id=\"2018\"]polymorphism[\/pb_glossary]<\/strong>) created by different pressure and [pb_glossary id=\"1767\"]temperature[\/pb_glossary] conditions.\n\n[h5p id=\"39\"]\n\n[caption id=\"attachment_4003\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.3-Phase-diagram-QR-Code.png\"><img class=\"size-thumbnail wp-image-448\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this interactive activity via this QR Code.[\/caption]\n\nSome [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks are named based on the highest [pb_glossary id=\"2016\"]grade[\/pb_glossary] of [pb_glossary id=\"2017\"]index mineral[\/pb_glossary] present. Chlorite [pb_glossary id=\"2007\"]schist[\/pb_glossary] includes the low-[pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"2017\"]index mineral[\/pb_glossary] chlorite. [pb_glossary id=\"966\"]Muscovite[\/pb_glossary] [pb_glossary id=\"2007\"]schist[\/pb_glossary] contains the slightly higher [pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"966\"]muscovite[\/pb_glossary], indicating a greater degree of [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary]. Garnet [pb_glossary id=\"2007\"]schist[\/pb_glossary] includes the high [pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"2017\"]index mineral[\/pb_glossary] garnet, and indicating it has experienced much higher pressures and temperatures than chlorite.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"40\"]\n\n[caption id=\"attachment_4002\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-449\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 6.3 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">6.4 Metamorphic Environments<\/span><\/h2>\n<span style=\"font-weight: 400\">As with [pb_glossary id=\"1753\"]igneous[\/pb_glossary] processes, [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks form at different zones of pressure (depth) and [pb_glossary id=\"1767\"]temperature[\/pb_glossary] as shown on the pressure-[pb_glossary id=\"1767\"]temperature[\/pb_glossary] (P-T) diagram. The term <\/span><b>[pb_glossary id=\"1991\"]facies[\/pb_glossary] <\/b><span style=\"font-weight: 400\">is an [pb_glossary id=\"1722\"]objective[\/pb_glossary] description of a rock. In [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks [pb_glossary id=\"1991\"]facies[\/pb_glossary]&nbsp;are groups of [pb_glossary id=\"1765\"]minerals[\/pb_glossary] called [pb_glossary id=\"1765\"]mineral[\/pb_glossary] assemblages. The names of <\/span><b>[pb_glossary id=\"2020\"]metamorphic facies[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> on the pressure-[pb_glossary id=\"1767\"]temperature[\/pb_glossary] diagram reflect [pb_glossary id=\"1765\"]minerals[\/pb_glossary] and [pb_glossary id=\"1765\"]mineral[\/pb_glossary] assemblages that are stable at these pressures and temperatures and provide information about the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] processes that have affected the rocks. This is useful when interpreting the history of a [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_3196\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fig-6.24-PT-graph.png\"><img class=\"wp-image-450 size-large\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-1024x683.png\" alt=\"\" width=\"1024\" height=\"683\"><\/a> Pressure-temperature graphs of various metamorphic facies. (Source: Peter Davis)[\/caption]\n\n<span style=\"font-weight: 400\">In the late 1800s, British geologist George Barrow mapped zones of [pb_glossary id=\"1765\"]index minerals[\/pb_glossary] in different [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] zones of an area that underwent [pb_glossary id=\"2024\"]regional metamorphism[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. Barrow outlined a progression of [pb_glossary id=\"2017\"]index minerals[\/pb_glossary], named the Barrovian Sequence, that represents increasing [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] [pb_glossary id=\"2016\"]grade[\/pb_glossary]: chlorite (slates and phyllites) -&gt; [pb_glossary id=\"966\"]biotite[\/pb_glossary] (phyllites and schists) -&gt; garnet (schists) -&gt; staurolite (schists) -&gt; kyanite (schists) -&gt; sillimanite (schists and gneisses).<\/span>\n\n[caption id=\"attachment_3199\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/1024px-Scotland_metamorphic_zones_EN.svg_.png\"><img class=\"size-medium wp-image-451\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-300x208.png\" alt=\"Metamorphic zones in Scotland show increasing metamorphic grade across a transect of a deformed mountain range.\" width=\"300\" height=\"208\"><\/a> Barrovian sequence in Scotland.[\/caption]\n\n<span style=\"font-weight: 400\">The first of the Barrovian sequence has a [pb_glossary id=\"1765\"]mineral[\/pb_glossary] group that is commonly found in the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] greenschist [pb_glossary id=\"1991\"]facies[\/pb_glossary]. Greenschist rocks form under relatively low pressure and temperatures and represent the fringes of [pb_glossary id=\"2024\"]regional metamorphism[\/pb_glossary]. The \u201cgreen\u201d part of the name is derived from &nbsp;green [pb_glossary id=\"1765\"]minerals[\/pb_glossary] like chlorite, serpentine, and epidote, and the \u201c[pb_glossary id=\"2007\"]schist[\/pb_glossary]\u201d part is applied due to the presence of platy [pb_glossary id=\"1765\"]minerals[\/pb_glossary] such as [pb_glossary id=\"966\"]muscovite[\/pb_glossary].<\/span>\n\n<span style=\"font-weight: 400\">Many different styles of [pb_glossary id=\"2020\"]metamorphic facies[\/pb_glossary] are recognized, tied to different geologic and [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] processes. Recognizing these [pb_glossary id=\"1991\"]facies[\/pb_glossary] is the most direct way to interpret the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] history of a rock. A simplified list of major [pb_glossary id=\"2020\"]metamorphic facies[\/pb_glossary] is given below.<\/span>\n<h3><span style=\"font-weight: 400\">6.4.1 Burial Metamorphism<\/span><\/h3>\n<b>[pb_glossary id=\"2021\"]Burial metamorphism[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> occurs when rocks are deeply buried, at depths of more than 2000 meters (1.24 miles)<\/span><span style=\"font-weight: 400\">. [pb_glossary id=\"2021\"]Burial metamorphism[\/pb_glossary] commonly occurs in [pb_glossary id=\"510\"]sedimentary basins[\/pb_glossary], where rocks are buried deeply by overlying [pb_glossary id=\"1756\"]sediments[\/pb_glossary]. As an [pb_glossary id=\"492\"]extension[\/pb_glossary] of [pb_glossary id=\"1905\"]diagenesis[\/pb_glossary], a process that occurs during [pb_glossary id=\"1760\"]lithification[\/pb_glossary] (<a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>), [pb_glossary id=\"2021\"]burial metamorphism[\/pb_glossary] can cause clay [pb_glossary id=\"1765\"]minerals[\/pb_glossary], such as smectite, in [pb_glossary id=\"1917\"]shales[\/pb_glossary] to change to another clay [pb_glossary id=\"1765\"]mineral[\/pb_glossary] illite. Or it can cause [pb_glossary id=\"967\"]quartz[\/pb_glossary] [pb_glossary id=\"1912\"]sandstone[\/pb_glossary] to metamorphose into the [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] such the Big Cottonwood [pb_glossary id=\"2038\"]Formation[\/pb_glossary] in the Wasatch Range of Utah. This [pb_glossary id=\"2038\"]formation[\/pb_glossary] was deposited as ancient near-[pb_glossary id=\"2273\"]shore[\/pb_glossary] sands in the late [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/7-geologic-time\/\">Chapter 7<\/a>), deeply buried and metamorphosed to [pb_glossary id=\"2013\"]quartzite[\/pb_glossary], folded, and later exposed at the surface in the Wasatch Range today. Increase of [pb_glossary id=\"1767\"]temperature[\/pb_glossary] with depth in combination with an increase of [pb_glossary id=\"1995\"]confining[\/pb_glossary] pressure produces low-[pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks with a [pb_glossary id=\"1765\"]mineral[\/pb_glossary] assemblages indicative of a zeolite [pb_glossary id=\"1991\"]facies[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. <\/span>\n<h3><span style=\"font-weight: 400\">6.4.2 Contact Metamorphism<\/span><\/h3>\n<strong>[pb_glossary id=\"2022\"]Contact metamorphism[\/pb_glossary]<\/strong> occurs in rock exposed to high [pb_glossary id=\"1767\"]temperature[\/pb_glossary] and low pressure, as might happen when hot [pb_glossary id=\"1750\"]magma[\/pb_glossary] intrudes into or [pb_glossary id=\"1751\"]lava[\/pb_glossary] flows over pre-existing [pb_glossary id=\"1766\"]protolith[\/pb_glossary]. This combination of high [pb_glossary id=\"1767\"]temperature[\/pb_glossary] and low pressure produces numerous [pb_glossary id=\"2020\"]metamorphic facies[\/pb_glossary]. The lowest pressure conditions produce [pb_glossary id=\"2015\"]hornfels[\/pb_glossary] [pb_glossary id=\"1991\"]facies[\/pb_glossary], while higher pressure creates greenschist, amphibolite, or granulite [pb_glossary id=\"1991\"]facies[\/pb_glossary].\n\nAs with all [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary], the [pb_glossary id=\"1766\"]parent rock[\/pb_glossary] [pb_glossary id=\"1997\"]texture[\/pb_glossary] and chemistry are major factors in determining the final outcome of the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] process, including what [pb_glossary id=\"2017\"]index minerals[\/pb_glossary] are present. Fine-grained [pb_glossary id=\"1917\"]shale[\/pb_glossary] and [pb_glossary id=\"1013\"]basalt[\/pb_glossary], which happen to be chemically similar, characteristically recrystallize to produce [pb_glossary id=\"2015\"]hornfels[\/pb_glossary]. [pb_glossary id=\"1912\"]Sandstone[\/pb_glossary] (silica) surrounding an [pb_glossary id=\"1753\"]igneous[\/pb_glossary] intrusion becomes [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] via [pb_glossary id=\"2022\"]contact metamorphism[\/pb_glossary], and [pb_glossary id=\"1929\"]limestone[\/pb_glossary] ([pb_glossary id=\"969\"]carbonate[\/pb_glossary]) becomes [pb_glossary id=\"2014\"]marble[\/pb_glossary].\n\n[caption id=\"attachment_3201\" align=\"alignleft\" width=\"185\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Metamorphic_Aureole_in_the_Henry_Mountains.jpg\">&lt;img class=\"wp-image-3201\" title=\"By Random Tree (Own work) [<a href=\"\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en&quot;\">CC0<\/a>], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AMetamorphic_Aureole_in_the_Henry_Mountains.JPG&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Metamorphic_Aureole_in_the_Henry_Mountains-300x225.jpg\" alt=\"Altered rock adjacent to an igneous intrusion.\" width=\"185\" height=\"139\"&gt;<\/a> Contact metamorphism in outcrop.[\/caption]When [pb_glossary id=\"2022\"]contact metamorphism[\/pb_glossary] occurs deeper in the Earth, [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] can be seen as rings of [pb_glossary id=\"1991\"]facies[\/pb_glossary] around the intrusion, resulting in <strong>[pb_glossary id=\"2023\"]aureoles[\/pb_glossary]<\/strong>. These differences in [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] appear as distinct [pb_glossary id=\"2009\"]bands[\/pb_glossary] surrounding the intrusion, as can be seen around the Alta Stock in Little Cottonwood Canyon, Utah. The Alta Stock is a [pb_glossary id=\"1014\"]granite[\/pb_glossary] intrusion surrounded first by rings of the [pb_glossary id=\"2017\"]index minerals[\/pb_glossary] [pb_glossary id=\"1791\"]amphibole[\/pb_glossary] (tremolite) and [pb_glossary id=\"1789\"]olivine[\/pb_glossary] (forsterite), with a ring of talc (dolostone) located further away<span style=\"font-weight: 400\">.<\/span>\n<h3><span style=\"font-weight: 400\">6.4.3 Regional Metamorphism<\/span><\/h3>\n<strong>[pb_glossary id=\"2024\"]Regional metamorphism[\/pb_glossary]<\/strong> occurs when [pb_glossary id=\"1766\"]parent rock[\/pb_glossary] is subjected to increased [pb_glossary id=\"1767\"]temperature[\/pb_glossary] and pressure over a large area, and is often located in mountain ranges created by converging [pb_glossary id=\"1653\"]continental[\/pb_glossary] crustal [pb_glossary id=\"1669\"]plates[\/pb_glossary]. This is the setting for the Barrovian sequence of rock [pb_glossary id=\"1991\"]facies[\/pb_glossary], with the lowest [pb_glossary id=\"2016\"]grade[\/pb_glossary] of [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] occurring on the flanks of the mountains and highest [pb_glossary id=\"2016\"]grade[\/pb_glossary] near the [pb_glossary id=\"1667\"]core[\/pb_glossary] of the mountain range, closest to the [pb_glossary id=\"1678\"]convergent[\/pb_glossary] boundary.\n\nAn example of an old regional [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] environment is visible in the northern Appalachian Mountains while driving east from New York state through Vermont and into New Hampshire. Along this route the degree of [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] gradually increases from sedimentary [pb_glossary id=\"1766\"]parent rock[\/pb_glossary], to low-[pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary], then higher-[pb_glossary id=\"2016\"]grade[\/pb_glossary] [pb_glossary id=\"1762\"]metamorphic rock[\/pb_glossary], and eventually the [pb_glossary id=\"1753\"]igneous[\/pb_glossary] [pb_glossary id=\"1667\"]core[\/pb_glossary]. The rock sequence is [pb_glossary id=\"1761\"]sedimentary rock[\/pb_glossary], [pb_glossary id=\"2004\"]slate[\/pb_glossary], [pb_glossary id=\"2006\"]phyllite[\/pb_glossary], [pb_glossary id=\"2007\"]schist[\/pb_glossary], [pb_glossary id=\"2010\"]gneiss[\/pb_glossary], [pb_glossary id=\"2011\"]migmatite[\/pb_glossary], and [pb_glossary id=\"1014\"]granite[\/pb_glossary]. In fact, New Hampshire is nicknamed the [pb_glossary id=\"1014\"]Granite[\/pb_glossary] State. The reverse sequence can be seen heading east, from eastern New Hampshire to the [pb_glossary id=\"1968\"]coast[\/pb_glossary]<span style=\"font-weight: 400\">.<\/span>\n<h3><span style=\"font-weight: 400\">6.4.4 Subduction Zone Metamorphism<\/span><\/h3>\n[caption id=\"attachment_3204\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4-25-Blueschist-e1492235808840-scaled.jpg\"><img class=\"wp-image-3204 size-medium\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-25-Blueschist-e1492235808840-scaled-1.jpg\" alt=\"A blue rock with bands of silvery mica grains.\" width=\"300\" height=\"225\"><\/a> Blueschist (Source: Peter Davis)[\/caption]\n\n[pb_glossary id=\"2025\"]Subduction zone[\/pb_glossary] metamorphism is a type of [pb_glossary id=\"2024\"]regional metamorphism[\/pb_glossary] that occurs when a [pb_glossary id=\"1683\"]slab[\/pb_glossary] of [pb_glossary id=\"1659\"]oceanic crust[\/pb_glossary] is [pb_glossary id=\"1680\"]subducted[\/pb_glossary] under [pb_glossary id=\"1653\"]continental crust[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/2-plate-tectonics\/\">Chapter 2<\/a>). Because rock is a good insulator, the [pb_glossary id=\"1767\"]temperature[\/pb_glossary] of the descending [pb_glossary id=\"1659\"]oceanic[\/pb_glossary] [pb_glossary id=\"1683\"]slab[\/pb_glossary] increases slowly relative to the more rapidly increasing pressure, creating a [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] environment of high pressure and low [pb_glossary id=\"1767\"]temperature[\/pb_glossary]. Glaucophane, which has a distinctive blue color, is an [pb_glossary id=\"2017\"]index mineral[\/pb_glossary] found in [pb_glossary id=\"2026\"]blueschist[\/pb_glossary] [pb_glossary id=\"1991\"]facies[\/pb_glossary] (see [pb_glossary id=\"2020\"]metamorphic facies[\/pb_glossary] diagram). The California [pb_glossary id=\"1968\"]Coast[\/pb_glossary] Range near San Francisco has [pb_glossary id=\"2026\"]blueschist[\/pb_glossary]-[pb_glossary id=\"1991\"]facies[\/pb_glossary] rocks created by [pb_glossary id=\"1680\"]subduction[\/pb_glossary]-zone [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary], which include rocks made of [pb_glossary id=\"2026\"]blueschist[\/pb_glossary], greenstone, and red [pb_glossary id=\"1927\"]chert[\/pb_glossary]. Greenstone, which is metamorphized [pb_glossary id=\"1013\"]basalt[\/pb_glossary], gets its color from the [pb_glossary id=\"2017\"]index mineral[\/pb_glossary] chlorite.\n<h3><span style=\"font-weight: 400\">6.4.5 Fault Metamorphism<\/span><\/h3>\n[caption id=\"attachment_3208\" align=\"alignright\" width=\"398\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4-28-Mylonite.jpg\"><img class=\"wp-image-453\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite-300x116.jpg\" alt=\"Layers of shears material with rotated grains.\" width=\"398\" height=\"153\"><\/a> Mylonite (Source: Peter Davis)[\/caption]\n\n<span style=\"font-weight: 400\">There are a range of [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks made along [pb_glossary id=\"2143\"]faults[\/pb_glossary]. Near the surface, rocks are involved in repeated [pb_glossary id=\"1661\"]brittle[\/pb_glossary] [pb_glossary id=\"2143\"]faulting[\/pb_glossary] produce a material called <\/span><i><span style=\"font-weight: 400\">rock flour,<\/span><\/i><span style=\"font-weight: 400\"> which is rock ground up to the particle size of flour used for food.<\/span> <span style=\"font-weight: 400\">At lower depths,<\/span> <span style=\"font-weight: 400\">[pb_glossary id=\"2143\"]faulting[\/pb_glossary] create <\/span><b>cataclastites<\/b><span style=\"font-weight: 400\">, chaotically-crushed mixes of rock material with little internal [pb_glossary id=\"1997\"]texture[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. At depths below [pb_glossary id=\"2027\"]cataclasites[\/pb_glossary], where [pb_glossary id=\"1994\"]strain[\/pb_glossary] becomes [pb_glossary id=\"1660\"]ductile[\/pb_glossary], [pb_glossary id=\"2028\"]mylonites[\/pb_glossary] are formed. <\/span><b>[pb_glossary id=\"2028\"]Mylonites[\/pb_glossary]<\/b> <span style=\"font-weight: 400\">are [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks created by dynamic [pb_glossary id=\"1998\"]recrystallization[\/pb_glossary] through directed [pb_glossary id=\"2190\"]shear forces[\/pb_glossary], generally resulting in a reduction of [pb_glossary id=\"1906\"]grain size[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. When larger, stronger crystals (like [pb_glossary id=\"968\"]feldspar[\/pb_glossary], [pb_glossary id=\"967\"]quartz[\/pb_glossary], garnet) embedded in a [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] matrix are [pb_glossary id=\"494\"]sheared[\/pb_glossary] into an asymmetrical eye-shaped crystal, an <\/span><b>[pb_glossary id=\"2029\"]augen[\/pb_glossary] <\/b><span style=\"font-weight: 400\">is formed<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3211\" align=\"aligncenter\" width=\"540\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4-29-Augen.jpg\"><img class=\"wp-image-454\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen.jpg\" alt=\"Rounded mineral grains from shear forces.\" width=\"540\" height=\"221\"><\/a> Examples of augens. (Source: Peter Davis)[\/caption]\n<h3><span style=\"font-weight: 400\">6.4.6 Shock Metamorphism<\/span><\/h3>\n[caption id=\"attachment_3212\" align=\"alignright\" width=\"218\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/820qtz.jpg\">&lt;img class=\"wp-image-3212\" title=\"By Glen A. Izett [Public domain], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3A820qtz.jpg&quot;\">via Wikimedia Commons<\/a>\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/820qtz-300x253.jpg\" alt=\"A small grain of sand showing a prismatic inside with lines across it.\" width=\"218\" height=\"184\"&gt;<\/a> Shock lamellae in a quartz grain.[\/caption]&nbsp;\n\n<b>Shock<\/b><span style=\"font-weight: 400\"> (also known as impact) <\/span><b>[pb_glossary id=\"1992\"]metamorphism[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> is [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary] resulting from [pb_glossary id=\"1254\"]meteor[\/pb_glossary] or other [pb_glossary id=\"482\"]bolide[\/pb_glossary] impacts, or from a similar high-pressure shock event. [pb_glossary id=\"2030\"]Shock metamorphism[\/pb_glossary] is the result of very high pressures (and higher, but less extreme temperatures) delivered relatively rapidly. [pb_glossary id=\"2030\"]Shock metamorphism[\/pb_glossary] produces planar [pb_glossary id=\"495\"]deformation[\/pb_glossary] features, tektites, shatter cones, and [pb_glossary id=\"967\"]quartz[\/pb_glossary] [pb_glossary id=\"2018\"]polymorphs[\/pb_glossary]. <\/span><span style=\"font-weight: 400\">[pb_glossary id=\"2030\"]Shock metamorphism[\/pb_glossary] produces planar [pb_glossary id=\"495\"]deformation[\/pb_glossary] features (shock [pb_glossary id=\"1938\"]laminae[\/pb_glossary]), which are narrow planes of glassy material with distinct orientations found in [pb_glossary id=\"1787\"]silicate[\/pb_glossary] [pb_glossary id=\"1765\"]mineral[\/pb_glossary] grains. Shocked [pb_glossary id=\"967\"]quartz[\/pb_glossary] has planar [pb_glossary id=\"495\"]deformation[\/pb_glossary] features<\/span><span style=\"font-weight: 400\">.&nbsp;<\/span>\n\n[caption id=\"attachment_3213\" align=\"alignleft\" width=\"187\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4_ShatterConeCharlevoix1.jpg\"><img class=\"wp-image-455\" title=\"By JMGastonguay (Own work) [CC BY-SA 4.0 (http:\/\/creativecommons.org\/licenses\/by-sa\/4.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1-300x225.jpg\" alt=\"Shatter cones are cone-shaped features, that show lines that converge to cone shapes.\" width=\"187\" height=\"140\"><\/a> Shatter cone.[\/caption]<span style=\"font-weight: 400\">Shatter cones are cone-shaped pieces of rock <\/span><span style=\"font-weight: 400\">created by dynamic branching [pb_glossary id=\"986\"]fractures[\/pb_glossary] caused by impacts<\/span><span style=\"font-weight: 400\">. While not strictly a [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] structure, they are common around [pb_glossary id=\"2030\"]shock metamorphism[\/pb_glossary]. Their diameter can range from microscopic to several meters. Fine-grained rocks with shatter cones show a distinctive horsetail pattern. <\/span>\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"2030\"]Shock metamorphism[\/pb_glossary] can also produce [pb_glossary id=\"2017\"]index minerals[\/pb_glossary], though they are typically only found via microscopic analysis. The [pb_glossary id=\"967\"]quartz[\/pb_glossary] [pb_glossary id=\"2440\"]polymorphs[\/pb_glossary] coesite and stishovite are indicative of [pb_glossary id=\"2030\"]impact metamorphism[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. As discussed in chapter 3, [pb_glossary id=\"2018\"]polymorphs[\/pb_glossary] are [pb_glossary id=\"1765\"]minerals[\/pb_glossary] with the same [pb_glossary id=\"1909\"]composition[\/pb_glossary] but different crystal structures. Intense pressure (&gt; 10 GPa) and moderate to high temperatures (700-1200 \u00b0C) are required to form these [pb_glossary id=\"1765\"]minerals[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_3214\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4_Two_tektites.jpg\"><img class=\"wp-image-456 size-medium\" title=\"By JMGastonguay (Own work) [CC BY-SA 4.0 (http:\/\/creativecommons.org\/licenses\/by-sa\/4.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites-300x200.jpg\" alt=\"Shatter cones are cone-shaped features, that show lines that converge to cone shapes.\" width=\"300\" height=\"200\"><\/a> Tektites[\/caption]<span style=\"font-weight: 400\">[pb_glossary id=\"2030\"]Shock metamorphism[\/pb_glossary] can also produce glass. <strong>Tektites<\/strong> are gravel-size glass grains ejected during an impact event<\/span><span style=\"font-weight: 400\">. They resemble [pb_glossary id=\"228\"]volcanic[\/pb_glossary] glass but, unlike [pb_glossary id=\"228\"]volcanic[\/pb_glossary] glass, tektites contain no water or [pb_glossary id=\"995\"]phenocrysts[\/pb_glossary], and have a different bulk and isotopic chemistry. Tektites contain partially melted [pb_glossary id=\"2036\"]inclusions[\/pb_glossary] of shocked [pb_glossary id=\"1765\"]mineral[\/pb_glossary] grains<\/span><span style=\"font-weight: 400\">. Although all are melt glasses, tektites are also chemically distinct from trinitite, which is produced from thermonuclear detonations<\/span><span style=\"font-weight: 400\">, and fulgurites, which are produced by lightning strikes<\/span><span style=\"font-weight: 400\">. All geologic glasses not derived from [pb_glossary id=\"228\"]volcanoes[\/pb_glossary] can be called with the general term pseudotachylytes<\/span><span style=\"font-weight: 400\">, a name which can also be applied to glasses created by [pb_glossary id=\"2143\"]faulting[\/pb_glossary]. The term pseudo in this context means \u2018false\u2019 or \u2018in the appearance of\u2019, a [pb_glossary id=\"990\"]volcanic rock[\/pb_glossary] called tachylite because the material observed looks like a [pb_glossary id=\"990\"]volcanic rock[\/pb_glossary],&nbsp;but is produced by significant [pb_glossary id=\"494\"]shear[\/pb_glossary] heating. <\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"41\"]\n\n[caption id=\"attachment_4128\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.4-Did-I-Get-It-QR-Code.png\"><img class=\"wp-image-457 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 6.4 via this QR Code.[\/caption]\n\n<div>\n\n[caption id=\"attachment_4005\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Metamorphic-Rocks-toast-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-458\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[embed]https:\/\/www.youtube.com\/embed\/Ncr-46YX-N0[\/embed]\n\n<\/div>\nhttps:\/\/youtu.be\/HUydPhIaQQU\n\n[caption id=\"attachment_4004\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Identifying-Metamorphic-Rock-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-459\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">Summary<\/span><\/h2>\n[pb_glossary id=\"1992\"]Metamorphism[\/pb_glossary] is the process that changes existing rocks (called [pb_glossary id=\"1766\"]protoliths[\/pb_glossary]) into new rocks with new [pb_glossary id=\"1765\"]minerals[\/pb_glossary] and new textures. Increases in [pb_glossary id=\"1767\"]temperature[\/pb_glossary] and pressure are the main causes of [pb_glossary id=\"1765\"]metamorphism[\/pb_glossary], with fluids adding important mobilization of materials. The primary way [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks are identified is with [pb_glossary id=\"1997\"]texture[\/pb_glossary]. [pb_glossary id=\"2002\"]Foliated[\/pb_glossary] textures come from platy [pb_glossary id=\"1765\"]minerals[\/pb_glossary] forming planes in a rock, while [pb_glossary id=\"2012\"]non-foliated[\/pb_glossary] [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks have no internal fabric. [pb_glossary id=\"2016\"]Grade[\/pb_glossary] describes the amount of [pb_glossary id=\"1993\"]metamorphism[\/pb_glossary] in a rock, and [pb_glossary id=\"1991\"]facies[\/pb_glossary] are a set of [pb_glossary id=\"1765\"]minerals[\/pb_glossary] that can help guide an observer to an interpretation of the [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] history of a rock. Different [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] or geologic environments cause [pb_glossary id=\"1992\"]metamorphism[\/pb_glossary], including collisions, [pb_glossary id=\"1680\"]subduction[\/pb_glossary], [pb_glossary id=\"2143\"]faulting[\/pb_glossary], and even impacts from space.\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n[h5p id=\"42\"]\n\n[caption id=\"attachment_4080\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Ch.6-Review-QR-Code.png\"><img class=\"wp-image-460 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the review quiz for Chapter 6 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n \t<li class=\"csl-entry\">Bucher, K., and Grapes, R., 2011, Petrogenesis of [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] rocks: Springer, 341 p.<\/li>\n \t<li class=\"csl-entry\">Jeong, I.-K., Heffner, R.H., Graf, M.J., and Billinge, S.J.L., 2003, Lattice dynamics and correlated atomic motion from the atomic pair distribution function: Phys. Rev. B Condens. Matter, v. 67, no. 10, p. 104301.<\/li>\n \t<li class=\"csl-entry\">Marshak, S., 2009, Essentials of Geology, 3rd or 4th Edition:<\/li>\n \t<li class=\"csl-entry\">Proctor, B.P., McAleer, R., Kunk, M.J., and Wintsch, R.P., 2013, Post-Taconic tilting and Acadian structural overprint of the classic Barrovian [pb_glossary id=\"1992\"]metamorphic[\/pb_glossary] [pb_glossary id=\"2213\"]gradient[\/pb_glossary] in Dutchess County, New York: Am. J. Sci., v. 313, no. 7, p. 649\u2013682.<\/li>\n \t<li class=\"csl-entry\">Timeline of Art History, 2007, Reference Reviews, v. 21, no. 8, p. 45\u201345.<\/li>\n<\/ol>\n<\/div>\n<span style=\"font-weight: 400\">&nbsp;<\/span>\n\n&nbsp;","rendered":"<figure id=\"attachment_3142\" aria-describedby=\"caption-attachment-3142\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/BCG3-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3142 size-large\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/BCG3-scaled-1.jpg\" alt=\"The painted wall is a large cliff\" width=\"1024\" height=\"768\" \/><\/a><figcaption id=\"caption-attachment-3142\" class=\"wp-caption-text\">Painted Wall of Black Canyon of the Gunnison National Park, Colorado, made of 1.7 billion-year old gneiss intruded by younger pegmatites.<\/figcaption><\/figure>\n<h1>6 Metamorphic Rocks<\/h1>\n<p><em>Contributing Author: Dr. Peter Davis, Pacific Lutheran University<\/em><\/p>\n<p><b>KEY CONCEPTS<\/b><\/p>\n<ul>\n<li>Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and pressure conditions of the metamorphic environment<\/li>\n<li>Identify and describe the three principal metamorphic agents<\/li>\n<li>Describe what recrystallization is and how it affects <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals<\/li>\n<li>Explain what foliation is and how it results from directed pressure and recrystallization<\/li>\n<li>Explain the relationships among slate, phyllite, schist, and gneiss in terms of metamorphic grade<\/li>\n<li>Define index mineral<\/li>\n<li>Explain how metamorphic facies relate to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> processes<\/li>\n<li>Describe what a contact aureole is and how contact metamorphism affects surrounding rock<\/li>\n<li>Describe the role of hydrothermal metamorphism in forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> deposits and ore bodies<\/li>\n<\/ul>\n<figure id=\"attachment_2480\" aria-describedby=\"caption-attachment-2480\" style=\"width: 379px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Fig-6-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-46\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-300x278.jpg\" alt=\"The rock cycle shows how different rock groups are interconnected. Metamorphic rocks can come from adding heat and\/or pressure to other metamorphic rock or sedimentary or igneous rocks\" width=\"379\" height=\"352\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-300x278.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-768x713.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-65x60.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-225x209.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1-350x325.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6-1.jpg 900w\" sizes=\"auto, (max-width: 379px) 100vw, 379px\" \/><\/a><figcaption id=\"caption-attachment-2480\" class=\"wp-caption-text\">Rock cycle showing the five materials (such as igneous rocks and sediment) and the processes by which one changes into another (such as weathering). (Source: Peter Davis)<\/figcaption><\/figure>\n<p><strong>Metamorphic rocks<\/strong>, <em>meta-<\/em> meaning change and &#8211;<em>morphos<\/em>&nbsp;meaning form, is one of the three rock categories in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1749\">rock cycle<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/1-understanding-science\/\">Chapter 1<\/a>). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">Metamorphic rock<\/a> material has been changed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>, pressure, and\/or fluids. <span style=\"font-weight: 400\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1749\">rock cycle<\/a> shows that both <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> and sedimentary rocks can become metamorphic rocks. And metamorphic rocks themselves&nbsp; can be re-metamorphosed. <\/span>Because metamorphism is caused by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonic<\/a> motion, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> provides geologists with a history book of how past <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> processes shaped our planet.<\/p>\n<h2><span style=\"font-weight: 400\">6.1 Metamorphic Processes<\/span><\/h2>\n<p>Metamorphism occurs when solid rock changes in composition and\/or texture without the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals melting, which is how <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous rock<\/a> is generated. Metamorphic source rocks, the rocks that experience the metamorphism, are called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">parent rock<\/a> or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a><\/strong>, from <em>proto<\/em>&#8211; meaning first, and <em>lithos- <\/em>meaning rock. Most metamorphic processes take place deep underground, inside the earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. During metamorphism, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a> chemistry is mildly changed by increased <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> (heat), a type of pressure called confining pressure, and\/or chemically reactive fluids. Rock texture is changed by heat, confining pressure, and a type of pressure called directed stress.<\/p>\n<h3><span style=\"font-weight: 400\">6.1.1&nbsp; Temperature (Heat) &nbsp;<\/span><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">Temperature<\/a> measures a substance\u2019s energy\u2014an increase in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> represents an increase in energy. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">Temperature<\/a> changes affect the chemical equilibrium or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cation<\/a> balance in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. At high temperatures atoms may vibrate so vigorously they jump from one position to another within the crystal lattice, which remains intact. In other words, this atom swapping can happen while the rock is still solid.<\/p>\n<p>The temperatures of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> lies in between surficial processes (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a>) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1749\">rock cycle<\/a>. Heat-driven metamorphism begins at temperatures as cold as 200\u02daC, and can continue to occur at temperatures as high as 700\u00b0C-1,100\u00b0C. Higher temperatures would create <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>, and thus, would no longer be a metamorphic process.&nbsp;<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">Temperature<\/a> increases with increasing depth in the Earth along a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_222\">geothermal gradient<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> records these depth-related <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> changes.<\/p>\n<h3><span style=\"font-weight: 400\">6.1.2 Pressure<\/span><\/h3>\n<p>Pressure <span style=\"font-weight: 400\">is the force exerted over a unit area on a material. Like heat, pressure can affect the chemical equilibrium of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in a rock. The pressure that affects metamorphic rocks can be grouped into confining pressure and directed stress. <strong>Stress<\/strong> is a scientific term indicating a&nbsp;force. <strong>Strain<\/strong> is the result of this stress, including metamorphic changes within <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/span><\/p>\n<h4><b>Confining Pressure<\/b><\/h4>\n<figure id=\"attachment_3148\" aria-describedby=\"caption-attachment-3148\" style=\"width: 450px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.1-02-Pressure-vs-Stress.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-432\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-300x252.png\" alt=\"Pressure is a state where all stresses on a body are equal. The magnitude of these balanced stresses increases with increasing depth within the earth. These stresses can not deform rocks other than to decrease their volume. Pressure is the term used becuase the concept of pressure is used in chemistry, which it the discipline of science used to understand the mineral reactions that occur within the rock. DIRECTED STRESSES s, s, One or more directions of stress are not equal in magnitude and or not in line with each other (non-coaxial). Unlike balanced stresses, the difference in these stresses can deform rocks within the earth.\" width=\"450\" height=\"378\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-300x252.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-1024x859.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-768x644.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-65x55.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-225x189.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress-350x294.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-02-Pressure-vs-Stress.png 1385w\" sizes=\"auto, (max-width: 450px) 100vw, 450px\" \/><\/a><figcaption id=\"caption-attachment-3148\" class=\"wp-caption-text\">Difference between pressure and stress and how they deform rocks. Pressure (or confining pressure) has equal stress (forces) in all directions and increases with depth under the Earth\u2019s surface. Under directed stress, some stress directions (forces) are stronger than others, and this can deform rocks. (Source: Peter Davis)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Pressure exerted on rocks under the surface&nbsp;is due to the simple fact that rocks lie on top of one another. When pressure is exerted from rocks above, it is balanced from below and sides, and is called <\/span><b>confining<\/b><span style=\"font-weight: 400\"> or <\/span><b>lithostatic pressure<\/b><span style=\"font-weight: 400\">. Confining pressure has equal pressure on all sides (see figure) and is&nbsp;responsible for causing chemical reactions to occur just like heat. These chemical reactions will cause new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> to form.&nbsp;<\/span><\/p>\n<p><span style=\"font-weight: 400\">Confining pressure is measured in bars and ranges from 1 bar at sea level to around 10,000 bars at the base of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. &nbsp;For metamorphic rocks, pressures range from a relatively low-pressure of 3,000 bars around 50,000 bars, which occurs around 15-35 kilometers below the surface.<\/span><\/p>\n<h4><b>Directed Stress<\/b><\/h4>\n<figure id=\"attachment_3150\" aria-describedby=\"caption-attachment-3150\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2_800px-P535973.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-433 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-300x225.jpg\" alt=\"Pebbles in quartzite deformed by directed stress\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2_800px-P535973.jpg 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3150\" class=\"wp-caption-text\">Pebbles (that used to be spherical or close to spherical) in quartzite deformed by directed stress<\/figcaption><\/figure>\n<p><strong>Directed stress<\/strong>, also called differential or tectonic stress, is an unequal balance of forces on a rock in one or more directions (see previous figure). Directed stresses are generated by the movement of lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. Stress indicates a type of force acting on rock. Strain describes the resultant processes caused by stress and includes metamorphic changes in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. In contrast to confining pressure, directed stress occurs at much lower pressures and does not generate chemical reactions that change <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> composition and atomic structure. Instead, directed stress modifies the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">parent rock<\/a> at a mechanical level, changing the arrangement, size, and\/or shape of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals. These crystalline changes create identifying textures, which is shown in the figure below comparing the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_992\">phaneritic<\/a> texture of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a> with the foliated texture of metamorphic gneiss.<\/p>\n<figure id=\"attachment_3152\" aria-describedby=\"caption-attachment-3152\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.1-03-Granite-vs-Gneiss.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-434 size-large\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-1024x443.jpg\" alt=\"Two rocks with very similar colors. One is a granite and another is a gneiss that has aligned dark minerals.\" width=\"1024\" height=\"443\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-1024x443.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-300x130.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-768x332.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-65x28.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-225x97.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss-350x151.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.1-03-Granite-vs-Gneiss.jpg 1175w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><figcaption id=\"caption-attachment-3152\" class=\"wp-caption-text\">An igneous rock granite (left) and foliated high-temperature and high-pressure metamorphic rock gneiss (right) illustrating a metamorphic texture. (Source: Peter Davis)<\/figcaption><\/figure>\n<p>Directed stresses produce rock textures in many ways. Crystals are rotated, changing their orientation in space. Crystals can get fractured, reducing their grain size. Conversely, they may grow larger as atoms migrate. Crystal shapes also become deformed. These mechanical changes occur via <strong>recrystallization<\/strong>, which is when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> dissolve from an area of rock experiencing high stress and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitate<\/a> or regrow in a location having lower stress. For example, recrystallization increases grain size much like adjacent soap bubbles coalesce to form larger ones. Recrystallization rearranges <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals without fracturing the rock structure, deforming the rock like silly putty; these changes provide important clues to understanding the creation and movement of deep underground rock faults.<\/p>\n<h3><span style=\"font-weight: 400\">6.1.3 Fluids<\/span><\/h3>\n<p>A third metamorphic agent is chemically reactive fluids that are expelled by crystallizing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> and created by metamorphic reactions. These reactive fluids are made of mostly water (H<sub>2<\/sub>O) and carbon dioxide (CO<sub>2<\/sub>), and smaller amounts of potassium (K), sodium (Na), iron (Fe), magnesium (Mg), calcium (Ca), and aluminum (Al). These fluids react with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a>, changing its chemical equilibrium and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> composition, in a process similar to the reactions driven by heat and pressure. In addition to using <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> found in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a>, the chemical reaction may incorporate substances contributed by the fluids to create new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. In general, this style of metamorphism, in which fluids play an important role, is called <strong>hydrothermal metamorphism<\/strong> or hydrothermal alteration. Water actively participates in chemical reactions and allows extra mobility of the components in hydrothermal alteration.<\/p>\n<p>Fluids-activated metamorphism is frequently involved in creating economically important <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> deposits that are located next to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> intrusions or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> bodies. For example, the mining districts in the Cottonwood Canyons and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">Basin<\/a> of northern Utah produce valuable ores such as argentite (silver <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>), galena (lead <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>), and chalcopyrite (copper iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>), as well as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> gold. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> deposits were created from the interaction between a granitic intrusion called the Little Cottonwood Stock and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1023\">country rock<\/a> consisting of mostly limestone and dolostone. Hot, circulating fluids expelled by the crystallizing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a> reacted with and dissolved the surrounding limestone and dolostone, precipitating out new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> created by the chemical reaction. Hydrothermal alternation of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> rock, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>, creates the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> <strong>serpentinite<\/strong>, a member of the serpentine subgroup of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. This metamorphic process happens at mid-ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">spreading centers<\/a> where newly formed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic crust<\/a> interacts with seawater.<\/p>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/BlackSmoker.jpg\">&lt;img class=\u00a0\u00bbwp-image-2545&Prime; title=\u00a0\u00bbBy University of Washington; NOAA\/OAR\/OER. (NOAA Photo Library: expl2366) [<\/a><a href=\"\/\/creativecommons.org\/licenses\/by\/2.0&quot;\">CC BY 2.0<\/a> or Public domain], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AExpl2366_-_Flickr_-_NOAA_Photo_Library.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/BlackSmoker-233&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbThere is a large build up of minerals around the vent\u00a0\u00bb width=\u00a0\u00bb304&Prime; height=\u00a0\u00bb392&Prime;&gt; Black smoker hydrothermal vent with a colony of giant (6\u2019+) tube worms.Some hydrothermal alterations remove <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">parent rock<\/a> rather than deposit them. This happens when seawater circulates down through <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fractures<\/a> in the fresh, still-hot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>, reacting with and removing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> ions from it. The dissolved <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are usually ions that do not fit snugly in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> crystal structure, such as copper. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>-laden water emerges from the sea floor via hydrothermal vents called <strong>black smokers<\/strong>, named after the dark-colored precipitates produced when the hot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_234\">vent<\/a> water meets cold seawater. (see Chapter 4, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">Igneous Rock<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">Volcanic<\/a> Processes) Ancient black smokers were an important source of copper ore for the inhabitants of Cyprus (Cypriots) as early as 4,000 BCE, and later by the Romans.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-37\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-37\" class=\"h5p-iframe\" data-content-id=\"37\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"6.1 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4000\" aria-describedby=\"caption-attachment-4000\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.1-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-435\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.1-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4000\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 6.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">6.2 Metamorphic textures <\/span><\/h2>\n<p><span style=\"font-weight: 400\">Metamorphic texture is the description of the shape and orientation of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> grains in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">Metamorphic rock<\/a> textures are foliated, non-foliated, or lineated are described below.<\/span><\/p>\n<figure id=\"attachment_3157\" aria-describedby=\"caption-attachment-3157\" style=\"width: 791px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MetaRx3.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-436 size-large\" title=\"(Source: Belinda Madsen) SLCC\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-791x1024.png\" alt=\"Table identifying the types of metamorphic rocks.\" width=\"791\" height=\"1024\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-791x1024.png 791w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-232x300.png 232w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-768x994.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-1187x1536.png 1187w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-1583x2048.png 1583w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-65x84.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-225x291.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MetaRx3-350x453.png 350w\" sizes=\"auto, (max-width: 791px) 100vw, 791px\" \/><\/a><figcaption id=\"caption-attachment-3157\" class=\"wp-caption-text\">Metamorphic rock identification table. (Source: Belinda Madsen)<\/figcaption><\/figure>\n<h3><span style=\"font-weight: 400\">6.2.1 Foliation and Lineation<\/span><\/h3>\n<p><span style=\"font-weight: 400\"><strong>Foliation<\/strong> is a term used that describes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> lined up in planes. Certain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, most notably the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> group, are mostly thin and planar by default. Foliated rocks typically appear as if the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are stacked like pages of a book, thus the use of the term \u2018folia\u2019, like a leaf<\/span><span style=\"font-weight: 400\">. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, with hornblende being a good example, are longer in one direction, linear like a pencil or a needle, rather than a planar-shaped book. These linear objects can also be aligned within a rock. This is referred to as a <\/span><b>lineation<\/b><span style=\"font-weight: 400\">. Linear crystals, such as hornblende, tourmaline, or stretched <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> grains, can be arranged as part of a foliation, a lineation, or foliation\/lineation together. If they lie on a plane with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a>, but with no common or preferred direction, this is foliation. If the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> line up and point in a common direction, but with no planar fabric, this is lineation. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> lie on a plane AND point in a common direction; this is both foliation and lineation. &nbsp;<\/span><\/p>\n<figure id=\"attachment_3164\" aria-describedby=\"caption-attachment-3164\" style=\"width: 588px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-06-Lineation.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-437\" title=\"Source: Peter Davis, Pacific Lutheran University\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-300x162.png\" alt=\"Lineation is aligned linear features in a rock. An example in the figure is a bundle of aligned straws.\" width=\"588\" height=\"318\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-300x162.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-1024x554.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-768x415.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-65x35.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-225x122.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation-350x189.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-06-Lineation.png 1311w\" sizes=\"auto, (max-width: 588px) 100vw, 588px\" \/><\/a><figcaption id=\"caption-attachment-3164\" class=\"wp-caption-text\">Example of lineation where minerals are aligned like a stack of straws or pencils. (Source: Peter Davis)<\/figcaption><\/figure>\n<figure id=\"attachment_3165\" aria-describedby=\"caption-attachment-3165\" style=\"width: 563px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-05-Foliationlineation.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-438\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-300x113.jpg\" alt=\"Aligned tourmaline crystals in line with foliation. Foliation is the fine &quot;layers&quot; of the rock.\" width=\"563\" height=\"213\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-300x113.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-1024x387.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-768x290.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-65x25.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-225x85.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation-350x132.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-05-Foliationlineation.jpg 1048w\" sizes=\"auto, (max-width: 563px) 100vw, 563px\" \/><\/a><figcaption id=\"caption-attachment-3165\" class=\"wp-caption-text\">An example of foliation WITH lineation. (Source: Peter Davis)<\/figcaption><\/figure>\n<figure id=\"attachment_3167\" aria-describedby=\"caption-attachment-3167\" style=\"width: 538px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-04-Foliation-without-lineation.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-439\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-300x222.png\" alt=\"Foliated surface displays non-lineated hornblende grains. A cross-section displays a cross section of foliated plagioclase and hornblende\" width=\"538\" height=\"399\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-300x222.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-1024x759.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-768x569.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-65x48.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-225x167.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation-350x259.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-04-Foliation-without-lineation.png 1242w\" sizes=\"auto, (max-width: 538px) 100vw, 538px\" \/><\/a><figcaption id=\"caption-attachment-3167\" class=\"wp-caption-text\">An example of foliation WITHOUT lineation. (Source: Peter Davis)<\/figcaption><\/figure>\n<p>Foliated metamorphic rocks are named based on the style of their foliations. Each rock name has a specific texture  that defines and distinguishes it, with their descriptions listed below.<\/p>\n<p><b>Slate<\/b><span style=\"font-weight: 400\"> is a fine-grained <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> that exhibits a foliation called <\/span><b>slaty cleavage <\/b><span style=\"font-weight: 400\">that is the flat orientation of the small platy crystals of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> and chlorite forming perpendicular to the direction of stress<\/span><i><span style=\"font-weight: 400\">.&nbsp;<\/span><\/i><span style=\"font-weight: 400\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in slate are too small to see with the unaided eye. The thin layers in slate may resemble sedimentary bedding, but they are a result of directed stress and may lie at angles to the original strata. In fact, original sedimentary layering may be partially or completely obscured by the foliation. Thin slabs of slate are often used as a building material for roofs and tiles.<\/span><\/p>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-Ehemaliger_Schiefertagebau_am_Brand.jpg\">&lt;img class=\u00a0\u00bbwp-image-3169&Prime; title=\u00a0\u00bbBy Uta Baumfelder at de.wikipedia (Own work) [Public domain], <\/a><a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AEhemaliger_Schiefertagebau_am_Brand.JPG&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-Ehemaliger_Schiefertagebau_am_Brand-300&#215;225.jpg\u00a0\u00bb alt=\u00a0\u00bbRock breaking along flat even planes.\u00a0\u00bb width=\u00a0\u00bb383&Prime; height=\u00a0\u00bb287&Prime;&gt; Slate mine in Germany cleavage.<\/p>\n<figure id=\"attachment_3171\" aria-describedby=\"caption-attachment-3171\" style=\"width: 420px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-07-Foliation-vs-bedding.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-440\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-300x200.jpg\" alt=\"Foliation is caused by metamorphism. Bedding is a result of sedimentary processes. They do not have to align.\" width=\"420\" height=\"280\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-300x200.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-1024x683.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-768x512.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-225x150.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding-350x233.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-07-Foliation-vs-bedding.jpg 1105w\" sizes=\"auto, (max-width: 420px) 100vw, 420px\" \/><\/a><figcaption id=\"caption-attachment-3171\" class=\"wp-caption-text\">Foliation vs. bedding. Foliation is caused by metamorphism. Bedding is a result of sedimentary processes. They do not have to align. (Source: Peter Davis)<\/figcaption><\/figure>\n<figure id=\"attachment_3174\" aria-describedby=\"caption-attachment-3174\" style=\"width: 377px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-10-Phyllite-with-fold-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3174\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-10-Phyllite-with-fold-scaled-1.jpg\" alt=\"A foliated rock with a slight sheen.\" width=\"377\" height=\"283\" \/><\/a><figcaption id=\"caption-attachment-3174\" class=\"wp-caption-text\">Phyllite with a small fold. (Source: Peter Davis)<\/figcaption><\/figure>\n<p><b>Phyllite <\/b><span style=\"font-weight: 400\">is a foliated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> in which platy <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> have grown larger and the surface of the foliation shows a sheen from light reflecting from the grains, perhaps even a wavy appearance, called crenulations<\/span><span style=\"font-weight: 400\">. Similar to phyllite but with even larger grains is the foliated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> <\/span><b>schist<\/b><span style=\"font-weight: 400\">, which has large platy grains visible as individual crystals. Common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">muscovite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">biotite<\/a>, and porphyroblasts of garnets. A porphyroblast is a large crystal of a particular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> surrounded by small grains. <\/span><b>Schistosity<\/b><span style=\"font-weight: 400\"> is a textural description of foliation created by the parallel alignment of platy visible grains. Some schists are named for their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> schist (mostly micas), garnet schist (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> schist with garnets), and staurolite schist (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> schists with staurolite).<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_3176\" aria-describedby=\"caption-attachment-3176\" style=\"width: 413px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-Schist_detail-e1492392805920.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-442\" title=\"Source: By Michael C. Rygel (Own work) [CC BY-SA 3.0 (http:\/\/creativecommons.org\/licenses\/by-sa\/3.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-300x184.jpg\" alt=\"Schist is a scalely looking foliated metamorphic rock.\" width=\"413\" height=\"253\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-300x184.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-768x470.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-65x40.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-225x138.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920-350x214.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-Schist_detail-e1492392805920.jpg 1011w\" sizes=\"auto, (max-width: 413px) 100vw, 413px\" \/><\/a><figcaption id=\"caption-attachment-3176\" class=\"wp-caption-text\">Schist<\/figcaption><\/figure>\n<figure id=\"attachment_3177\" aria-describedby=\"caption-attachment-3177\" style=\"width: 420px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-11-Muscovite-schist.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-443\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-300x165.jpg\" alt=\"Shiny foliated rock with small crystals of red faceted garnet among the foliated micas.\" width=\"420\" height=\"230\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-300x165.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-1024x562.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-768x421.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-65x36.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-225x123.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist-350x192.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-11-Muscovite-schist.jpg 1105w\" sizes=\"auto, (max-width: 420px) 100vw, 420px\" \/><\/a><figcaption id=\"caption-attachment-3177\" class=\"wp-caption-text\">Garnet staurolite muscovite schist. (Source: Peter Davis)<\/figcaption><\/figure>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2_Gneiss.jpg\">&lt;img class=\u00a0\u00bbwp-image-3179&Prime; title=\u00a0\u00bbBy No machine-readable author provided. Siim assumed (based on copyright claims). [<\/a><a href=\"\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a> or <a href=\"\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AGneiss.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2_Gneiss-300&#215;181.jpg\u00a0\u00bb alt=\u00a0\u00bbAlternating bands of light and dark minerals.\u00a0\u00bb width=\u00a0\u00bb354&Prime; height=\u00a0\u00bb213&Prime;&gt; Gneiss&nbsp;<\/p>\n<p><b>Gneissic banding&nbsp;<\/b><span style=\"font-weight: 400\">is a metamorphic foliation<\/span> <span style=\"font-weight: 400\">in which visible <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> separate into dark and light bands or lineations. These grains tend to be coarse and often folded. A rock with this texture is called <\/span><b>gneiss<\/b><span style=\"font-weight: 400\">. Since gneisses form at the highest temperatures and pressures, some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_224\">partial melting<\/a> may occur. This partially melted rock is a transition between metamorphic and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> rocks called a <\/span><b>migmatite<\/b><b>.<\/b><\/p>\n<figure id=\"attachment_2482\" aria-describedby=\"caption-attachment-2482\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/06.2-15-Mt-Blaca-Migmatite-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-48\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-300x225.jpg\" alt=\"Swirling bands of light and dark minerals.\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-1024x768.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-1536x1152.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-15-Mt-Blaca-Migmatite-1.jpg 1600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-2482\" class=\"wp-caption-text\">Migmatite, a rock which was partially molten. (Source: Peter Davis)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Migmatites appear as dark and light banded gneiss that may be swirled or twisted some since some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> started to melt. Thin accumulations of light colored rock layers can occur in a darker rock that are parallel to each other, or even cut across the gneissic foliation. The lighter colored layers are interpreted to be the result of the separation of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> melt from the adjacent highly metamorphosed darker layers, or injection of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> melt from some distance away. <\/span><\/p>\n<h3><span style=\"font-weight: 400\">6.2.2 Non-foliated<\/span><\/h3>\n<figure id=\"attachment_3185\" aria-describedby=\"caption-attachment-3185\" style=\"width: 413px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-21-Marble-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3185\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-21-Marble-scaled-1.jpg\" alt=\"pink crystallized rock with interlocking crystals\" width=\"413\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-3185\" class=\"wp-caption-text\">Marble (Source: Peter Davis)<\/figcaption><\/figure>\n<figure id=\"attachment_3188\" aria-describedby=\"caption-attachment-3188\" style=\"width: 420px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.2-20-Baraboo.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-445\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-300x275.jpg\" alt=\"Crystallized rock with interlocking crystals.\" width=\"420\" height=\"385\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-300x275.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-1024x940.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-768x705.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-1536x1409.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-2048x1879.jpg 2048w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-65x60.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-225x206.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.2-20-Baraboo-350x321.jpg 350w\" sizes=\"auto, (max-width: 420px) 100vw, 420px\" \/><\/a><figcaption id=\"caption-attachment-3188\" class=\"wp-caption-text\">Baraboo Quartzite<\/figcaption><\/figure>\n<p><b>Non-foliated<\/b><span style=\"font-weight: 400\"> textures do not have lineations, foliations, or other alignments of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> grains. Non-foliated metamorphic rocks are typically composed of just one <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>, and therefore, usually show the effects of metamorphism with recrystallization in which crystals grow together, but with no preferred direction. The two most common examples of non-foliated rocks are quartzite and marble. <\/span><b>Quartzite <\/b><span style=\"font-weight: 400\">is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a> sandstone. In quartzites, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> grains from the original sandstone are enlarged and interlocked by recrystallization. A defining characteristic for distinguishing quartzite from sandstone is that when broken with a rock hammer, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> crystals break across the grains. In a sandstone, only a thin <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> cement holds the grains together, meaning that a broken piece of sandstone will leave the grains intact. Because most sandstones are rich in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> is a mechanically and chemically durable substance, quartzite is very hard and resistant to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>.<\/span><\/p>\n<p><b>Marble<\/b><span style=\"font-weight: 400\"> is metamorphosed limestone (or dolostone) composed of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> (or dolomite). Recrystallization typically generates larger interlocking crystals of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> or dolomite. Marble and quartzite often look similar, but these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are considerably softer than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>. Another way to distinguish marble from quartzite is with a drop of dilute hydrochloric acid. Marble will effervesce (fizz) if it is made of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>.<\/span><\/p>\n<p><span style=\"font-weight: 400\">A third non-foliated rock is <\/span><b>hornfels <\/b><span style=\"font-weight: 400\">identified by its dense, fine grained, hard, blocky or splintery texture composed of several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. Crystals in hornfels grow smaller with metamorphism, and become so small that specialized study is required to identify them. These are common around <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_991\">intrusive<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> bodies and<\/span><span style=\"font-weight: 400\">&nbsp;are hard to identify. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a> of hornfels can be even harder to distinguish, which can be anything from mudstone to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>.<\/span><\/p>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sample_of_Quartzite-e1493780752118.jpg\">&lt;img class=\u00a0\u00bbwp-image-3191&Prime; title=\u00a0\u00bbBy Manishwiki15 (Own work) [<\/a><a href=\"\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;\">CC BY-SA 3.0<\/a>], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3ASample_of_Quartzite.JPG&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sample_of_Quartzite-e1493780752118-300&#215;210.jpg\u00a0\u00bb alt=\u00a0\u00bbInterlocking quartz grains in a quartzite.\u00a0\u00bb width=\u00a0\u00bb413&Prime; height=\u00a0\u00bb289&Prime;&gt; Macro view of quartzite. Note the interconnectedness of the grains.<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/640px-CoralPinkSandDunesSand.jpg\">&lt;img class=\u00a0\u00bbwp-image-3192&Prime; title=\u00a0\u00bbBy Wilson44691 (Own work) [Public domain], <\/a><a href=\"\/\/commons.wikimedia.org\/wiki\/File%3ACoralPinkSandDunesSand.JPG&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/640px-CoralPinkSandDunesSand-300&#215;225.jpg\u00a0\u00bb alt=\u00a0\u00bbUndeformed quartz grains do not interlock.\u00a0\u00bb width=\u00a0\u00bb420&Prime; height=\u00a0\u00bb315&Prime;&gt; Unmetamorphosed, unconsolidated sand grains have space between the grains.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-38\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-38\" class=\"h5p-iframe\" data-content-id=\"38\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"6.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4001\" aria-describedby=\"caption-attachment-4001\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.2-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-446\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.2-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4001\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 6.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">6.3 Metamorphic Grade<\/span><\/h2>\n<figure id=\"attachment_3194\" aria-describedby=\"caption-attachment-3194\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4_Garnet_Mica_Schist_Syros_Greece.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-447 size-medium\" title=\"By Graeme Churchard (GOC53) http:\/\/www.flickr.com\/people\/graeme\/ [CC BY 2.0 (http:\/\/creativecommons.org\/licenses\/by\/2.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece-300x225.jpg\" alt=\"Large weathered garnet crystals in a matrix of platy micas. The garnets are round-shaped with octagonal sides.\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Garnet_Mica_Schist_Syros_Greece.jpg 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3194\" class=\"wp-caption-text\">Garnet schist.<\/figcaption><\/figure>\n<p>Metamorphic grade refers to the range of metamorphic change a rock undergoes, progressing from low (little metamorphic change) grade to high (significant metamorphic change) grade. Low-grade metamorphism begins at temperatures and pressures just above <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a> conditions. The sequence slate\u2192phyllite\u2192schist\u2192gneiss illustrates an increasing metamorphic grade.<\/p>\n<p>Geologists use <strong>index minerals<\/strong> that form at certain temperatures and pressures to identify metamorphic grade. These index minerals also provide important clues to a rock\u2019s sedimentary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a> and the metamorphic conditions that created it. Chlorite, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">muscovite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">biotite<\/a>, garnet, and staurolite are index minerals representing a respective sequence of low-to-high grade rock. The figure shows a <strong>phase diagram<\/strong> of three index minerals\u2014sillimanite, kyanite, and andalusite\u2014with the same chemical formula (Al<sub>2<\/sub>SiO<sub>5<\/sub>) but having different crystal structures (<strong>polymorphism<\/strong>) created by different pressure and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> conditions.<\/p>\n<div id=\"h5p-39\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-39\" class=\"h5p-iframe\" data-content-id=\"39\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"6.3 Phase diagram\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4003\" aria-describedby=\"caption-attachment-4003\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.3-Phase-diagram-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-448\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Phase-diagram-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4003\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this interactive activity via this QR Code.<\/figcaption><\/figure>\n<p>Some metamorphic rocks are named based on the highest grade of index mineral present. Chlorite schist includes the low-grade index mineral chlorite. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">Muscovite<\/a> schist contains the slightly higher grade <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">muscovite<\/a>, indicating a greater degree of metamorphism. Garnet schist includes the high grade index mineral garnet, and indicating it has experienced much higher pressures and temperatures than chlorite.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-40\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-40\" class=\"h5p-iframe\" data-content-id=\"40\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"6.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4002\" aria-describedby=\"caption-attachment-4002\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.3-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-449\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.3-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4002\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 6.3 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">6.4 Metamorphic Environments<\/span><\/h2>\n<p><span style=\"font-weight: 400\">As with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> processes, metamorphic rocks form at different zones of pressure (depth) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> as shown on the pressure-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> (P-T) diagram. The term <\/span><b>facies <\/b><span style=\"font-weight: 400\">is an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1722\">objective<\/a> description of a rock. In metamorphic rocks facies&nbsp;are groups of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> assemblages. The names of <\/span><b>metamorphic facies<\/b><span style=\"font-weight: 400\"> on the pressure-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> diagram reflect <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> assemblages that are stable at these pressures and temperatures and provide information about the metamorphic processes that have affected the rocks. This is useful when interpreting the history of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a>.<\/span><\/p>\n<figure id=\"attachment_3196\" aria-describedby=\"caption-attachment-3196\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fig-6.24-PT-graph.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-450 size-large\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-1024x683.png\" alt=\"\" width=\"1024\" height=\"683\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-1024x683.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-300x200.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-768x512.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-1536x1024.png 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-2048x1365.png 2048w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-65x43.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-225x150.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig-6.24-PT-graph-350x233.png 350w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><figcaption id=\"caption-attachment-3196\" class=\"wp-caption-text\">Pressure-temperature graphs of various metamorphic facies. (Source: Peter Davis)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In the late 1800s, British geologist George Barrow mapped zones of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">index minerals<\/a> in different metamorphic zones of an area that underwent regional metamorphism<\/span><span style=\"font-weight: 400\">. Barrow outlined a progression of index minerals, named the Barrovian Sequence, that represents increasing metamorphic grade: chlorite (slates and phyllites) -&gt; <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">biotite<\/a> (phyllites and schists) -&gt; garnet (schists) -&gt; staurolite (schists) -&gt; kyanite (schists) -&gt; sillimanite (schists and gneisses).<\/span><\/p>\n<figure id=\"attachment_3199\" aria-describedby=\"caption-attachment-3199\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/1024px-Scotland_metamorphic_zones_EN.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-451\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-300x208.png\" alt=\"Metamorphic zones in Scotland show increasing metamorphic grade across a transect of a deformed mountain range.\" width=\"300\" height=\"208\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-300x208.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-768x532.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-65x45.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-225x156.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_-350x242.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1024px-Scotland_metamorphic_zones_EN.svg_.png 1024w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3199\" class=\"wp-caption-text\">Barrovian sequence in Scotland.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The first of the Barrovian sequence has a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> group that is commonly found in the metamorphic greenschist facies. Greenschist rocks form under relatively low pressure and temperatures and represent the fringes of regional metamorphism. The \u201cgreen\u201d part of the name is derived from &nbsp;green <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> like chlorite, serpentine, and epidote, and the \u201cschist\u201d part is applied due to the presence of platy <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">muscovite<\/a>.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Many different styles of metamorphic facies are recognized, tied to different geologic and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> processes. Recognizing these facies is the most direct way to interpret the metamorphic history of a rock. A simplified list of major metamorphic facies is given below.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">6.4.1 Burial Metamorphism<\/span><\/h3>\n<p><b>Burial metamorphism<\/b><span style=\"font-weight: 400\"> occurs when rocks are deeply buried, at depths of more than 2000 meters (1.24 miles)<\/span><span style=\"font-weight: 400\">. Burial metamorphism commonly occurs in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_510\">sedimentary basins<\/a>, where rocks are buried deeply by overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a>. As an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extension<\/a> of diagenesis, a process that occurs during <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1760\">lithification<\/a> (<a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>), burial metamorphism can cause clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, such as smectite, in shales to change to another clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> illite. Or it can cause <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> sandstone to metamorphose into the quartzite such the Big Cottonwood Formation in the Wasatch Range of Utah. This formation was deposited as ancient near-shore sands in the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1261\">Proterozoic<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/7-geologic-time\/\">Chapter 7<\/a>), deeply buried and metamorphosed to quartzite, folded, and later exposed at the surface in the Wasatch Range today. Increase of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> with depth in combination with an increase of confining pressure produces low-grade metamorphic rocks with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> assemblages indicative of a zeolite facies<\/span><span style=\"font-weight: 400\">. <\/span><\/p>\n<h3><span style=\"font-weight: 400\">6.4.2 Contact Metamorphism<\/span><\/h3>\n<p><strong>Contact metamorphism<\/strong> occurs in rock exposed to high <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and low pressure, as might happen when hot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> intrudes into or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1751\">lava<\/a> flows over pre-existing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protolith<\/a>. This combination of high <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and low pressure produces numerous metamorphic facies. The lowest pressure conditions produce hornfels facies, while higher pressure creates greenschist, amphibolite, or granulite facies.<\/p>\n<p>As with all <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">parent rock<\/a> texture and chemistry are major factors in determining the final outcome of the metamorphic process, including what index minerals are present. Fine-grained shale and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>, which happen to be chemically similar, characteristically recrystallize to produce hornfels. Sandstone (silica) surrounding an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> intrusion becomes quartzite via contact metamorphism, and limestone (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a>) becomes marble.<\/p>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Metamorphic_Aureole_in_the_Henry_Mountains.jpg\">&lt;img class=\u00a0\u00bbwp-image-3201&Prime; title=\u00a0\u00bbBy Random Tree (Own work) [<\/a><a href=\"\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en&quot;\">CC0<\/a>], <a href=\"\/\/commons.wikimedia.org\/wiki\/File%3AMetamorphic_Aureole_in_the_Henry_Mountains.JPG&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Metamorphic_Aureole_in_the_Henry_Mountains-300&#215;225.jpg\u00a0\u00bb alt=\u00a0\u00bbAltered rock adjacent to an igneous intrusion.\u00a0\u00bb width=\u00a0\u00bb185&Prime; height=\u00a0\u00bb139&Prime;&gt; Contact metamorphism in outcrop.When contact metamorphism occurs deeper in the Earth, metamorphism can be seen as rings of facies around the intrusion, resulting in <strong>aureoles<\/strong>. These differences in metamorphism appear as distinct bands surrounding the intrusion, as can be seen around the Alta Stock in Little Cottonwood Canyon, Utah. The Alta Stock is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a> intrusion surrounded first by rings of the index minerals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a> (tremolite) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> (forsterite), with a ring of talc (dolostone) located further away<span style=\"font-weight: 400\">.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">6.4.3 Regional Metamorphism<\/span><\/h3>\n<p><strong>Regional metamorphism<\/strong> occurs when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">parent rock<\/a> is subjected to increased <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and pressure over a large area, and is often located in mountain ranges created by converging <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> crustal <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. This is the setting for the Barrovian sequence of rock facies, with the lowest grade of metamorphism occurring on the flanks of the mountains and highest grade near the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> of the mountain range, closest to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">convergent<\/a> boundary.<\/p>\n<p>An example of an old regional metamorphic environment is visible in the northern Appalachian Mountains while driving east from New York state through Vermont and into New Hampshire. Along this route the degree of metamorphism gradually increases from sedimentary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">parent rock<\/a>, to low-grade <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a>, then higher-grade <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a>, and eventually the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a>. The rock sequence is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a>, slate, phyllite, schist, gneiss, migmatite, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a>. In fact, New Hampshire is nicknamed the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">Granite<\/a> State. The reverse sequence can be seen heading east, from eastern New Hampshire to the coast<span style=\"font-weight: 400\">.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">6.4.4 Subduction Zone Metamorphism<\/span><\/h3>\n<figure id=\"attachment_3204\" aria-describedby=\"caption-attachment-3204\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4-25-Blueschist-e1492235808840-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3204 size-medium\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-25-Blueschist-e1492235808840-scaled-1.jpg\" alt=\"A blue rock with bands of silvery mica grains.\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-3204\" class=\"wp-caption-text\">Blueschist (Source: Peter Davis)<\/figcaption><\/figure>\n<p>Subduction zone metamorphism is a type of regional metamorphism that occurs when a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic crust<\/a> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducted<\/a> under <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/2-plate-tectonics\/\">Chapter 2<\/a>). Because rock is a good insulator, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> of the descending <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> increases slowly relative to the more rapidly increasing pressure, creating a metamorphic environment of high pressure and low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>. Glaucophane, which has a distinctive blue color, is an index mineral found in blueschist facies (see metamorphic facies diagram). The California Coast Range near San Francisco has blueschist&#8211;facies rocks created by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>-zone metamorphism, which include rocks made of blueschist, greenstone, and red chert. Greenstone, which is metamorphized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>, gets its color from the index mineral chlorite.<\/p>\n<h3><span style=\"font-weight: 400\">6.4.5 Fault Metamorphism<\/span><\/h3>\n<figure id=\"attachment_3208\" aria-describedby=\"caption-attachment-3208\" style=\"width: 398px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4-28-Mylonite.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-453\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite-300x116.jpg\" alt=\"Layers of shears material with rotated grains.\" width=\"398\" height=\"153\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite-300x116.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite-65x25.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite-225x87.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite-350x135.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-28-Mylonite.jpg 752w\" sizes=\"auto, (max-width: 398px) 100vw, 398px\" \/><\/a><figcaption id=\"caption-attachment-3208\" class=\"wp-caption-text\">Mylonite (Source: Peter Davis)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">There are a range of metamorphic rocks made along faults. Near the surface, rocks are involved in repeated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1661\">brittle<\/a> faulting produce a material called <\/span><i><span style=\"font-weight: 400\">rock flour,<\/span><\/i><span style=\"font-weight: 400\"> which is rock ground up to the particle size of flour used for food.<\/span> <span style=\"font-weight: 400\">At lower depths,<\/span> <span style=\"font-weight: 400\">faulting create <\/span><b>cataclastites<\/b><span style=\"font-weight: 400\">, chaotically-crushed mixes of rock material with little internal texture<\/span><span style=\"font-weight: 400\">. At depths below cataclasites, where strain becomes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1660\">ductile<\/a>, mylonites are formed. <\/span><b>Mylonites<\/b> <span style=\"font-weight: 400\">are metamorphic rocks created by dynamic recrystallization through directed shear forces, generally resulting in a reduction of grain size<\/span><span style=\"font-weight: 400\">. When larger, stronger crystals (like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, garnet) embedded in a metamorphic matrix are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">sheared<\/a> into an asymmetrical eye-shaped crystal, an <\/span><b>augen <\/b><span style=\"font-weight: 400\">is formed<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3211\" aria-describedby=\"caption-attachment-3211\" style=\"width: 540px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4-29-Augen.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-454\" title=\"Source: Peter Davis\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen.jpg\" alt=\"Rounded mineral grains from shear forces.\" width=\"540\" height=\"221\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen.jpg 601w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen-300x123.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen-65x27.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen-225x92.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4-29-Augen-350x143.jpg 350w\" sizes=\"auto, (max-width: 540px) 100vw, 540px\" \/><\/a><figcaption id=\"caption-attachment-3211\" class=\"wp-caption-text\">Examples of augens. (Source: Peter Davis)<\/figcaption><\/figure>\n<h3><span style=\"font-weight: 400\">6.4.6 Shock Metamorphism<\/span><\/h3>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/820qtz.jpg\">&lt;img class=\u00a0\u00bbwp-image-3212&Prime; title=\u00a0\u00bbBy Glen A. Izett [Public domain], <\/a><a href=\"\/\/commons.wikimedia.org\/wiki\/File%3A820qtz.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/820qtz-300&#215;253.jpg\u00a0\u00bb alt=\u00a0\u00bbA small grain of sand showing a prismatic inside with lines across it.\u00a0\u00bb width=\u00a0\u00bb218&Prime; height=\u00a0\u00bb184&Prime;&gt; Shock lamellae in a quartz grain.&nbsp;<\/p>\n<p><b>Shock<\/b><span style=\"font-weight: 400\"> (also known as impact) <\/span><b>metamorphism<\/b><span style=\"font-weight: 400\"> is metamorphism resulting from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1254\">meteor<\/a> or other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_482\">bolide<\/a> impacts, or from a similar high-pressure shock event. Shock metamorphism is the result of very high pressures (and higher, but less extreme temperatures) delivered relatively rapidly. Shock metamorphism produces planar <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> features, tektites, shatter cones, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> polymorphs. <\/span><span style=\"font-weight: 400\">Shock metamorphism produces planar <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> features (shock laminae), which are narrow planes of glassy material with distinct orientations found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> grains. Shocked <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> has planar <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> features<\/span><span style=\"font-weight: 400\">.&nbsp;<\/span><\/p>\n<figure id=\"attachment_3213\" aria-describedby=\"caption-attachment-3213\" style=\"width: 187px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4_ShatterConeCharlevoix1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-455\" title=\"By JMGastonguay (Own work) [CC BY-SA 4.0 (http:\/\/creativecommons.org\/licenses\/by-sa\/4.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1-300x225.jpg\" alt=\"Shatter cones are cone-shaped features, that show lines that converge to cone shapes.\" width=\"187\" height=\"140\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_ShatterConeCharlevoix1.jpg 640w\" sizes=\"auto, (max-width: 187px) 100vw, 187px\" \/><\/a><figcaption id=\"caption-attachment-3213\" class=\"wp-caption-text\">Shatter cone.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Shatter cones are cone-shaped pieces of rock <\/span><span style=\"font-weight: 400\">created by dynamic branching <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fractures<\/a> caused by impacts<\/span><span style=\"font-weight: 400\">. While not strictly a metamorphic structure, they are common around shock metamorphism. Their diameter can range from microscopic to several meters. Fine-grained rocks with shatter cones show a distinctive horsetail pattern. <\/span><\/p>\n<p><span style=\"font-weight: 400\">Shock metamorphism can also produce index minerals, though they are typically only found via microscopic analysis. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> polymorphs coesite and stishovite are indicative of impact metamorphism<\/span><span style=\"font-weight: 400\">. As discussed in chapter 3, polymorphs are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> with the same composition but different crystal structures. Intense pressure (&gt; 10 GPa) and moderate to high temperatures (700-1200 \u00b0C) are required to form these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/span><\/p>\n<figure id=\"attachment_3214\" aria-describedby=\"caption-attachment-3214\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/06.4_Two_tektites.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-456 size-medium\" title=\"By JMGastonguay (Own work) [CC BY-SA 4.0 (http:\/\/creativecommons.org\/licenses\/by-sa\/4.0)], via Wikimedia Commons\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites-300x200.jpg\" alt=\"Shatter cones are cone-shaped features, that show lines that converge to cone shapes.\" width=\"300\" height=\"200\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites-300x200.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites-225x150.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites-350x234.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/06.4_Two_tektites.jpg 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3214\" class=\"wp-caption-text\">Tektites<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Shock metamorphism can also produce glass. <strong>Tektites<\/strong> are gravel-size glass grains ejected during an impact event<\/span><span style=\"font-weight: 400\">. They resemble <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> glass but, unlike <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> glass, tektites contain no water or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_995\">phenocrysts<\/a>, and have a different bulk and isotopic chemistry. Tektites contain partially melted inclusions of shocked <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> grains<\/span><span style=\"font-weight: 400\">. Although all are melt glasses, tektites are also chemically distinct from trinitite, which is produced from thermonuclear detonations<\/span><span style=\"font-weight: 400\">, and fulgurites, which are produced by lightning strikes<\/span><span style=\"font-weight: 400\">. All geologic glasses not derived from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> can be called with the general term pseudotachylytes<\/span><span style=\"font-weight: 400\">, a name which can also be applied to glasses created by faulting. The term pseudo in this context means \u2018false\u2019 or \u2018in the appearance of\u2019, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_990\">volcanic rock<\/a> called tachylite because the material observed looks like a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_990\">volcanic rock<\/a>,&nbsp;but is produced by significant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">shear<\/a> heating. <\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-41\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-41\" class=\"h5p-iframe\" data-content-id=\"41\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"6.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4128\" aria-describedby=\"caption-attachment-4128\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/6.4-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-457 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/6.4-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4128\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 6.4 via this QR Code.<\/figcaption><\/figure>\n<div>\n<figure id=\"attachment_4005\" aria-describedby=\"caption-attachment-4005\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Metamorphic-Rocks-toast-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-458\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Metamorphic-Rocks-toast-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4005\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Metamorphic Rocks (&amp; toast)\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/Ncr-46YX-N0?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Identifying Metamorphic Rocks -- Earth Rocks!\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/HUydPhIaQQU?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<figure id=\"attachment_4004\" aria-describedby=\"caption-attachment-4004\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Identifying-Metamorphic-Rock-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-459\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Identifying-Metamorphic-Rock-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4004\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">Summary<\/span><\/h2>\n<p>Metamorphism is the process that changes existing rocks (called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1766\">protoliths<\/a>) into new rocks with new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and new textures. Increases in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and pressure are the main causes of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">metamorphism<\/a>, with fluids adding important mobilization of materials. The primary way metamorphic rocks are identified is with texture. Foliated textures come from platy <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> forming planes in a rock, while non-foliated metamorphic rocks have no internal fabric. Grade describes the amount of metamorphism in a rock, and facies are a set of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that can help guide an observer to an interpretation of the metamorphic history of a rock. Different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> or geologic environments cause metamorphism, including collisions, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>, faulting, and even impacts from space.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-42\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-42\" class=\"h5p-iframe\" data-content-id=\"42\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 6 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4080\" aria-describedby=\"caption-attachment-4080\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Ch.6-Review-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-460 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.6-Review-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4080\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 6 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n<li class=\"csl-entry\">Bucher, K., and Grapes, R., 2011, Petrogenesis of metamorphic rocks: Springer, 341 p.<\/li>\n<li class=\"csl-entry\">Jeong, I.-K., Heffner, R.H., Graf, M.J., and Billinge, S.J.L., 2003, Lattice dynamics and correlated atomic motion from the atomic pair distribution function: Phys. Rev. B Condens. Matter, v. 67, no. 10, p. 104301.<\/li>\n<li class=\"csl-entry\">Marshak, S., 2009, Essentials of Geology, 3rd or 4th Edition:<\/li>\n<li class=\"csl-entry\">Proctor, B.P., McAleer, R., Kunk, M.J., and Wintsch, R.P., 2013, Post-Taconic tilting and Acadian structural overprint of the classic Barrovian metamorphic gradient in Dutchess County, New York: Am. J. Sci., v. 313, no. 7, p. 649\u2013682.<\/li>\n<li class=\"csl-entry\">Timeline of Art History, 2007, Reference Reviews, v. 21, no. 8, p. 45\u201345.<\/li>\n<\/ol>\n<\/div>\n<p><span style=\"font-weight: 400\">&nbsp;<\/span><\/p>\n<p>&nbsp;<\/p>\n<div class=\"media-attributions clear\" prefix:cc=\"http:\/\/creativecommons.org\/ns#\" prefix:dc=\"http:\/\/purl.org\/dc\/terms\/\"><h2>Mention de la source du contenu multim\u00e9dia<\/h2><ul><li >Rock Cycle       <\/li><li >Pressure vs Stress       <\/li><li >800px-P535973       <\/li><li >Granite vs Gneiss       <\/li><li >6.1 Did I Get It QR Code       <\/li><li >MetaRx3       <\/li><li >Lineation       <\/li><li >Foliation+lineation       <\/li><li >Foliation-without lineation       <\/li><li >Foliation vs bedding       <\/li><li >Schist_detail       <\/li><li >Muscovite schist       <\/li><li >Migmatite       <\/li><li >Baraboo       <\/li><li >6.2 Did I Get It QR Code       <\/li><li >Garnet_Mica_Schist_Syros_Greece       <\/li><li >6.3 Phase diagram QR Code       <\/li><li >6.3 Did I Get It QR Code       <\/li><li >PT-graph       <\/li><li >Scotland_metamorphic_zones_EN.svg       <\/li><li >Mylonite       <\/li><li >Augen       <\/li><li >ShatterConeCharlevoix1       <\/li><li >ShatterConeCharlevoix1       <\/li><li >6.4 Did I Get It QR Code       <\/li><li >Metamorphic Rocks (&amp; toast) Youtube QR Code       <\/li><li >Identifying Metamorphic Rock Youtube QR Code       <\/li><li >Ch.6 Review QR Code       <\/li><\/ul><\/div><div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">d\u00e9finition<\/span><template id=\"term_461_1767\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1767\"><div tabindex=\"-1\"><p>Sedimentary rocks made of mineral grains weathered as mechanical detritus of previous rocks, e.g. sand, gravel, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1992\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1992\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1998\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1998\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1765\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1765\"><div tabindex=\"-1\"><p>A rule that says the outer valence shell of electrons is complete when it contains 8 electrons.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2002\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2002\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2004\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2004\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2006\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2006\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2007\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2007\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2010\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2010\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2017\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2017\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2020\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2020\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1669\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1669\"><div tabindex=\"-1\"><p>Glaciers that form in cool or mountainous areas.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1654\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1654\"><div tabindex=\"-1\"><p>Rock with abraded surfaces formed in deserts.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2023\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2023\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2022\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2022\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1999\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1999\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2403\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2403\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1749\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1749\"><div tabindex=\"-1\"><p>Minerals with a luster similar to metal and contain metals, including valuable elements like lead, zinc, copper, tin, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1762\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1762\"><div tabindex=\"-1\"><p>Deposit of heavy ores in stream or beach sediments.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1753\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1753\"><div tabindex=\"-1\"><p>Metallic mineral deposit which forms near mid-ocean ridges.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1909\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1909\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1997\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1997\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2418\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2418\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1766\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1766\"><div tabindex=\"-1\"><p>Minerals with the same composition and different crystal structures<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1658\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1658\"><div tabindex=\"-1\"><p>Dangerous flooding that occurs in arid regions.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1995\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1995\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1996\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1996\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1780\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1780\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1761\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1761\"><div tabindex=\"-1\"><p>A highly weathered soil deposit that consists of aluminum ores.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1750\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1750\"><div tabindex=\"-1\"><p>Minerals that have a luster that is not similar to metal, and typically do not contain valuable metals like copper, lead, zinc, tin, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_222\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_222\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1993\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1993\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1994\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1994\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_992\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_992\"><div tabindex=\"-1\"><p>An intrusive ultramafic rock, which is the main component of the mantle. The minerals in peridotite are typically olivine with some pyroxene.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1014\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1014\"><div tabindex=\"-1\"><p>Area behind the arc, which can be subject to compressional (causing thrusted mountain belts) or extensional (causing back-arc basins) forces.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1906\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1906\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1893\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1893\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1785\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1785\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2143\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2143\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1778\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1778\"><div tabindex=\"-1\"><p>[glossary]<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2402\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2402\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_508\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_508\"><div tabindex=\"-1\"><p>(Source: National Park Service modified after Garber et al. 1989)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_973\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_973\"><div tabindex=\"-1\"><figure id=\"attachment_4617\" aria-describedby=\"caption-attachment-4617\" style=\"width: 768px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Latrobe_gold_nugget_Natural_History_Museum.jpg\"><img class=\"wp-image-929 size-full\" title=\"&quot;I,\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/02\/Latrobe_gold_nugget_Natural_History_Museum.jpg\" alt=\"The nugget has cube shapes.\" width=\"768\" height=\"1024\"><\/a><figcaption id=\"caption-attachment-4617\" class=\"wp-caption-text\">The Latrobe Gold Nugget, as seen on display in the London Natural History Museum, is 717 grams and displays the rare cubic form of native gold. Most gold, even larger nuggets, grow in confined spaces where the euhedral nature of the mineral is not seen.<\/figcaption><\/figure>\n<h1>16 Energy and Mineral Resources<\/h1>\n<p><b>KEY CONCEPTS<\/b><\/p>\n<ul>\n<li>Describe how a\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a>\u00a0resource is different from a\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a>\u00a0resource.<\/li>\n<li>Compare the pros and cons of extracting and using fossil fuels and conventional and unconventional petroleum sources.<\/li>\n<li>Describe how metallic\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are formed\u00a0and extracted.<\/li>\n<li>Understand how society uses\u00a0nonmetallic\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0resources.<\/li>\n<\/ul>\n<figure id=\"attachment_4618\" aria-describedby=\"caption-attachment-4618\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16.0_Stone-Tool.jpg\"><img class=\"wp-image-930 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.0_Stone-Tool-300x225.jpg\" alt=\"The rock has a smooth side and a sharp side.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-4618\" class=\"wp-caption-text\">A Mode 1 Oldowan tool used for chopping<\/figcaption><\/figure>\n<p>This text has previously discussed geology\u2019s pioneers, such as scientists James Hutton and Charles Lyell, but the first real \u201cgeologists\u201d were the hominids who picked up stones and began the stone age. Maybe stones were first used as curiosity pieces, maybe as weapons, but ultimately, they were used as tools. This was the Paleolithic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1244\">Period<\/a>, the beginning of geologic study, and it dates back 2.6 million years to east Africa.<\/p>\n<p>In modern times, geologic knowledge is important for locating economically valuable materials for society\u2019s use. In fact, all things we use come from only three sources: they are farmed, hunted or fished, or mined. At the turn of the twentieth century, speculation was rampant that food supplies would not keep pace with world demand, suggesting the need to develop artificial fertilizers. Sources of fertilizer ingredients are: nitrogen is processed from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a>, using the Haber process for the manufacture of ammonia from atmospheric nitrogen and hydrogen; potassium comes from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1744\">hydrosphere<\/a>, such as lakes or ocean evaporation; and phosphorus is mined from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>, such as minerals like apatite from phosphorite rock, which is found in Florida, North Carolina, Idaho, Utah, and around the world. \u00a0Thus, without mining and processing of natural materials, modern civilization would not exist. Indeed, geologists are essential in this process.<\/p>\n<h2><strong>16.1 Mining<\/strong><\/h2>\n<figure id=\"attachment_4619\" aria-describedby=\"caption-attachment-4619\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Simplified_world_mining_map_1.png\"><img class=\"wp-image-931 size-large\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Simplified_world_mining_map_1-1024x383.png\" alt=\"The map shows many different materials that are mined across the world.\" width=\"1024\" height=\"383\"><\/a><figcaption id=\"caption-attachment-4619\" class=\"wp-caption-text\">Map of world mining areas.<\/figcaption><\/figure>\n<p><strong>Mining<\/strong>\u00a0is defined as extracting valuable materials from the Earth for society\u2019s use. Usually, these include solid materials such as gold, iron,\u00a0coal, diamond, sand, and gravel, but materials can also include fluid resources such as\u00a0oil\u00a0and\u00a0natural gas. Modern\u00a0mining\u00a0has a long relationship with modern society. The oldest mine dates back 40,000 years to the Lion Cavern in Swaziland where there is evidence of\u00a0concentrated\u00a0digging\u00a0 into the Earth for hematite, an important iron ore used as red dye. Resources extracted by\u00a0mining\u00a0are generally considered to be\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a>.<\/p>\n<h3><b>16.1.1. Renewable vs. nonrenewable resources<\/b><\/h3>\n<p>Resources generally come in two major categories:\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">Renewable<\/a> resources can be reused over and over or their availability replicated over a short human life span; <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a> resources cannot.<\/p>\n<figure id=\"attachment_4621\" aria-describedby=\"caption-attachment-4621\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16.1_Hoover_Dam_Colorado_River.jpg\"><img class=\"wp-image-932 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.1_Hoover_Dam_Colorado_River-300x200.jpg\" alt=\"The dam has a large lake behind it\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-4621\" class=\"wp-caption-text\">Hoover Dam provides hydroelectric energy and stores water for southern Nevada.<\/figcaption><\/figure>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">Renewable<\/a><\/strong><strong>\u00a0resources<\/strong> are materials present in our environment that can be exploited and replenished. Some common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> energy sources are linked with green energy sources because they are associated with relatively small or easily remediated environmental impact. For example, solar energy comes from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1250\">fusion<\/a> within the Sun, which radiates electromagnetic energy. This energy reaches the Earth constantly and consistently and should continue to do so for about five billion more years. Wind energy, also related to solar energy, is maybe the oldest <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> energy and is used to sail ships and power windmills. Both solar and wind-generated energy are variable on Earth\u2019s surface. These limitations are offset because we can use energy storing devices, such as batteries or electricity exchanges between producing sites. The Earth\u2019s heat, known as geothermal energy, can be viable anywhere that geologists drill deeply enough. In practice, geothermal energy is more useful where heat flow is great, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> zones or regions with a thinner <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. Hydroelectric dams provide energy by allowing water to fall through the dam under gravity, which activates turbines that produce the energy. Ocean tides are also a reliable energy source. All of these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> resources provide energy that powers society. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> resources are plant and animal matter, which are used for food, clothing, and other necessities, but are being researched as possible energy sources.<\/p>\n<figure id=\"attachment_4622\" aria-describedby=\"caption-attachment-4622\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Rough_diamond.jpg\"><img class=\"wp-image-933 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rough_diamond-300x226.jpg\" alt=\"The diamond is clear and pyramidal.\" width=\"300\" height=\"226\"><\/a><figcaption id=\"caption-attachment-4622\" class=\"wp-caption-text\">Natural, octahedral shape of diamond.<\/figcaption><\/figure>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">Nonrenewable<\/a><\/strong><strong>\u00a0resources<\/strong> cannot be replenished at a sustainable rate. They are finite within human time frames. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a> resources come from planetary, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a>, or long-term biologic processes and include materials such as gold, lead, copper, diamonds, marble, sand, natural gas, oil, and coal. Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a> resources include specific concentrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> listed on the periodic table; some are compounds of those <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. For example, if society needs iron (Fe) sources, then an exploration geologist will search for iron-rich deposits that can be economically extracted. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">Nonrenewable<\/a> resources may be abandoned when other materials become cheaper or serve a better purpose. For example, coal is abundantly available in England and other nations, but because oil and natural gas are available at a lower cost and lower environmental impact, coal use has decreased. Economic competition among <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a> resources is shifting use away from coal in many developed countries.<\/p>\n<h3><b>16.1.2. Ore<\/b><\/h3>\n<figure id=\"attachment_4623\" aria-describedby=\"caption-attachment-4623\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/MichiganBIF.jpg\"><img class=\"wp-image-934 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MichiganBIF-300x206.jpg\" alt=\"The rock shows red and brown layering.\" width=\"300\" height=\"206\"><\/a><figcaption id=\"caption-attachment-4623\" class=\"wp-caption-text\">Banded-iron formations are an important ore of iron (Fe).<\/figcaption><\/figure>\n<p>Earth\u2019s materials include the\u00a0periodic table <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. However, it is rare that\u00a0these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> are concentrated\u00a0to the point where it is profitable to extract and process the material into usable products. Any place where a valuable material is\u00a0concentrated\u00a0is a geologic and geochemical\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_765\">anomaly<\/a>. A body of material from which one or more valuable substances can be\u00a0mined\u00a0at a profit, is called an\u00a0<strong>ore<\/strong>\u00a0deposit. Typically, the term\u00a0ore\u00a0is used for only metal-bearing\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, but it can be applied to valuable <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a>\u00a0resource concentrations such as fossil fuels, building stones, and other nonmetal deposits, even\u00a0groundwater. If a metal-bearing resource is not profitable to mine, it is referred to as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> deposit. The term <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1738\">natural resource<\/a><\/strong> is more common than\u00a0the term ore\u00a0for non-metal-bearing materials.<\/p>\n<figure id=\"attachment_4624\" aria-describedby=\"caption-attachment-4624\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16-Reserve-vs-Resource.jpg\"><img class=\"wp-image-935 size-medium\" style=\"font-weight: bold;background-color: transparent;text-align: inherit\" title=\"Source: Chris Johnson\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16-Reserve-vs-Resource-300x233.jpg\" alt=\"Diagram shows the small box of &quot;reserves&quot; within a larger box of &quot;resources&quot;. There is also an &quot;inferred resources&quot; box that is slightly larger than &quot;proven reserves&quot; box and an &quot;undiscovered resources&quot; box slightly larger than the resources box.\" width=\"300\" height=\"233\"><\/a><figcaption id=\"caption-attachment-4624\" class=\"wp-caption-text\">Diagram illustrating the relative abundance of proven reserves, inferred reserves, resources, and undiscovered resources. (Source: Chris Johnson)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">It is implicit that the technology to mine is available, economic conditions are suitable, and political, social and environmental considerations are satisfied in order to classify a\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1738\">natural resource<\/a> deposit as ore. \u00a0Depending on the substance, it can be concentrated in a narrow vein or distributed over a large area as a low-concentration ore. Some materials are mined directly from bodies of water (e.g. sylvite for potassium; water through desalination) and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a> (e.g. nitrogen for fertilizers). \u00a0These differences lead to various methods of mining, and differences in terminology depending on the certainty. <strong>Ore m<\/strong><\/span><b>ineral resource<\/b><span style=\"font-weight: 400\"> is used for an indication of ore that is potentially extractable, and the term <strong>ore\u00a0<\/strong><\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> reserve<\/b><span style=\"font-weight: 400\"> is used for a well defined (proven), profitable amount of extractable ore.<\/span><\/p>\n<figure id=\"attachment_4625\" aria-describedby=\"caption-attachment-4625\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/McKelveyDiagram.jpg\"><img class=\"wp-image-936 size-large\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/McKelveyDiagram-1024x596.jpg\" alt=\"The chart shows reserves vs. resources\" width=\"1024\" height=\"596\"><\/a><figcaption id=\"caption-attachment-4625\" class=\"wp-caption-text\">McKelvey diagram showing different definitions for different degrees of concentration and understanding of mineral deposits.<\/figcaption><\/figure>\n<h3><b>16.1.3. Mining Techniques<\/b><\/h3>\n<p>The mining style is determined by technology, social license, and economics. It is in the best interest of the company extracting the resources to do so in a cost-effective way. Fluid resources, such as\u00a0oil\u00a0and gas, are extracted by drilling wells and pumping. Over the years, drilling has evolved into a complex discipline in which directional drilling can produce multiple bifurcations and curves originating from a single drill collar at the surface. Using geophysical tools like\u00a0seismic\u00a0imaging, geologists can pinpoint resources and extract efficiently.<\/p>\n<p>Solid resources are extracted by two\u00a0principal methods of which there are many variants.\u00a0<strong>Surface mining<\/strong>\u00a0is used to remove material from the outermost part\u00a0of the Earth.\u00a0<strong>Open pit<\/strong>\u00a0<strong>mining<\/strong>\u00a0is used to target shallow, broadly disseminated resources.<\/p>\n<figure id=\"attachment_4626\" aria-describedby=\"caption-attachment-4626\" style=\"width: 352px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Bingham_Canyon_mine_2016.jpg\"><img class=\"wp-image-4626\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bingham_Canyon_mine_2016-1.jpg\" alt=\"The image is a large hole in a mountainside.\" width=\"352\" height=\"212\"><\/a><figcaption id=\"caption-attachment-4626\" class=\"wp-caption-text\">Bingham Canyon Mine, Utah. This open pit mine is the largest man-made removal of rock in the world.<\/figcaption><\/figure>\n<p>Open pit mining requires careful study of the ore body through surface mapping and drilling exploratory cores. The pit is progressively deepened through additional mining cuts to extract the ore. Typically, the pit\u2019s walls are as steep as can be safely managed. Once the pit is deepened, widening the top is very expensive. A steep wall is thus an engineering balance between efficient and profitable mining (from the company's point of view) and mass wasting (angle of repose from a safety p0int of view) so that there is less waste to remove. The waste is called non-valuable rock or overburden and moving it is costly. Occasionally, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_246\">landslides<\/a> do occur, such as the very large <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_246\">landslide<\/a> in the Kennecott Bingham Canyon mine, Utah, in 2013. These events are costly and dangerous. The job of engineering geologists is to carefully monitor the mine; when company management heeds their warnings, there is ample time and action to avoid or prepare for any slide.<\/p>\n<figure id=\"attachment_4627\" aria-describedby=\"caption-attachment-4627\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Coal_mine_Wyoming.jpg\"><img class=\"size-medium wp-image-938\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coal_mine_Wyoming-300x200.jpg\" alt=\"A large machine is removing coal.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-4627\" class=\"wp-caption-text\">A surface coal mine in Wyoming.<\/figcaption><\/figure>\n<p><strong>Strip mining<\/strong>\u00a0and\u00a0<strong>mountaintop mining<\/strong>\u00a0are\u00a0surface mining\u00a0techniques that are used to mine resources that cover large areas, especially layered resources, such as coal. In this method, an entire mountaintop or rock layer is removed to access the\u00a0ore\u00a0below. Surface mining\u2019s\u00a0environmental impacts are usually much greater due to the large surface footprint that\u2019s disturbed.<\/p>\n<figure id=\"attachment_4628\" aria-describedby=\"caption-attachment-4628\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/UndergroundOilShaleEstonia.jpg\"><img class=\"size-medium wp-image-939\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/UndergroundOilShaleEstonia-300x193.jpg\" alt=\"A large truck is loading material underground.\" width=\"300\" height=\"193\"><\/a><figcaption id=\"caption-attachment-4628\" class=\"wp-caption-text\">Underground mining in Estonia of Oil Shale.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><strong>Underground mining<\/strong>\u00a0is a method often used to mine higher-grade, more localized, or very\u00a0concentrated\u00a0resources. For one example, geologists mine some\u00a0underground ore\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0by introducing chemical agents, which dissolve\u00a0the target\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>.\u00a0Then, they bring the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a> to the surface where\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> extracts the material. But more often, a\u00a0mining\u00a0shaft tunnel or a large network of these shafts and tunnels is dug to access the material. The decision to mine underground or from Earth\u2019s surface is dictated by\u00a0the ore\u00a0deposit\u2019s concentration, depth, geometry, land-use policies, economics, surrounding rock strength, and physical access to the\u00a0ore. For example, to use surface mining techniques for deeper deposits might require removing too much material, or the necessary method may be too dangerous or impractical, or removing the entire overburden may be too expensive, or the\u00a0mining\u00a0footprint would be too large. These factors may prevent geologists from surface mining\u00a0materials and cause a project to be\u00a0mined\u00a0underground. The mining method\u00a0and its feasibility depends on the commodity\u2019s price and the cost of the technology needed to remove it and deliver it to market.\u00a0Thus,\u00a0mines\u00a0and the towns that support them come and go as the commodity price varies.\u00a0And, conversely, technological advances and market demands may reopen\u00a0mines\u00a0and revive ghost towns.<\/p>\n<h3><b>16.1.4. Concentrating and Refining<\/b><\/h3>\n<figure id=\"attachment_4629\" aria-describedby=\"caption-attachment-4629\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16.1_phosphate_smelting_furnace.jpg\"><img class=\"wp-image-940 size-medium\" title=\"&quot;Alfred\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.1_phosphate_smelting_furnace-300x233.jpg\" alt=\"A man is operating a large machine that looks like a blast furnace.\" width=\"300\" height=\"233\"><\/a><figcaption id=\"caption-attachment-4629\" class=\"wp-caption-text\">A phosphate smelting operation in Alabama, 1942.<\/figcaption><\/figure>\n<p>All\u00a0ore\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0occur mixed with less desirable components called\u00a0<strong>gangue<\/strong>. The process of physically separating\u00a0gangue\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0from\u00a0ore bearing\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0is called\u00a0<strong>concentrating<\/strong>. Separating a desired\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>\u00a0from a host\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0by chemical means, including heating, is called\u00a0<strong>smelting<\/strong>. \u00a0Finally, taking a metal such as copper and removing other trace metals such as gold or silver is done through the <strong>refining<\/strong> process. Typically, <strong>refining<\/strong> is done one of three ways: 1. Materials can either be mechanically separated and processed based on the ore\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u2019s unique physical properties, such as recovering placer\u00a0gold based on its high density. 2. Materials can be heated to chemically separate desired components, such as refining\u00a0crude\u00a0oil\u00a0into\u00a0gasoline. 3. Materials can be smelted, in which controlled chemical reactions unbind metals from the\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0they are contained in, such as when copper is taken out of chalcopyrite (CuFeS<sub>2<\/sub>).\u00a0Mining,\u00a0concentrating,\u00a0smelting,\u00a0and\u00a0refining\u00a0processes require enormous energy. Continual advances in metallurgy- and\u00a0mining-practice strive to develop ever more energy efficient and environmentally benign processes and practices.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-109\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-109\" class=\"h5p-iframe\" data-content-id=\"109\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"16.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4901\" aria-describedby=\"caption-attachment-4901\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/16.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-941\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-4901\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 16.1 via this QR Code.<\/figcaption><\/figure>\n<h2><strong>16.2. Fossil Fuels<\/strong><\/h2>\n<figure id=\"attachment_4630\" aria-describedby=\"caption-attachment-4630\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16.2_Castle_Gate_Power_Plant_Utah_2007.jpg\"><img class=\"wp-image-942 size-medium\" title=\"&quot;<a\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.2_Castle_Gate_Power_Plant_Utah_2007-300x188.jpg\" alt=\"The power plant has smoke coming from it\" width=\"300\" height=\"188\"><\/a><figcaption id=\"caption-attachment-4630\" class=\"wp-caption-text\">Coal power plant in Helper, Utah.<\/figcaption><\/figure>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">Fossils<\/a><\/strong><strong>\u00a0fuels<\/strong> are extractable sources of stored energy that were created by ancient ecosystems. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1738\">natural resources<\/a> that typically fall under this category are coal, oil, petroleum, and natural gas. These resources were originally formed via photosynthesis by living organisms such as plants, phytoplankton, algae, and cyanobacteria. This energy is actually <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossil<\/a> solar energy, since the sun\u2019s ancient energy was converted by ancient organisms into tissues that preserved the chemical energy within the fossil fuel. Of course, as the energy is used, just like photosynthetic respiration that occurs today, carbon enters the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a> as CO<sub>2<\/sub>, causing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_757\">climate<\/a> consequences (see <a href=\"https:\/\/opengeology.org\/textbook\/15-global-climate-change\/\">Chapter 15<\/a>).\u00a0Today humanity uses fossil fuels\u00a0for most of the world\u2019s energy.<\/p>\n<figure id=\"attachment_4631\" aria-describedby=\"caption-attachment-4631\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Coral_Outcrop_Flynn_Reef.jpg\"><img class=\"wp-image-4631 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-2.jpg\" alt=\"The reef has many intricacies.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-4631\" class=\"wp-caption-text\">Modern coral reefs and other highly-productive shallow marine environments are thought to be the sources of most petroleum resources.<\/figcaption><\/figure>\n<p>Converting solar energy by living organisms into hydrocarbon fossil fuels is a complex process. As organisms die, they decompose slowly, usually due to being buried rapidly, and the chemical energy stored within the organisms\u2019 tissues is buried within surrounding geologic materials. All fossil\u00a0fuels contain carbon that was produced in an ancient environment. In environments rich with organic matter such as swamps, coral reefs, and planktonic blooms, there is a higher potential for fossil fuels to accumulate. Indeed, there is some evidence that over geologic time, organic hydrocarbon fossil fuel material was highly produced globally. Lack of oxygen and moderate temperatures in the environment seem to help preserve these organic substances. Also, the heat and pressure applied to organic material after it is buried contribute to transforming it into higher quality materials, such as brown coal to anthracite and oil to gas. Heat and pressure can also cause mobile materials to migrate to conditions suitable for extraction.<\/p>\n<h3><b>16.2.1. Fossil Fuels<\/b><\/h3>\n<h4><span style=\"font-weight: 400\">OIL AND GAS<\/span><\/h4>\n<figure id=\"attachment_4632\" aria-describedby=\"caption-attachment-4632\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Oil_Reserves.png\"><img class=\"wp-image-944 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Oil_Reserves-300x136.png\" alt=\"Darker countries are higher in oil\" width=\"300\" height=\"136\"><\/a><figcaption id=\"caption-attachment-4632\" class=\"wp-caption-text\">World Oil Reserves in 2013. Scale in billions of barrels.<\/figcaption><\/figure>\n<p><strong>P<\/strong>etroleum is principally derived from organic-rich shallow\u00a0marine\u00a0sedimentary deposits where the remains of micro-organisms like plankton accumulated in fine grained <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a>. Petroleum\u2019s liquid component is called\u00a0<strong>oil,<\/strong>\u00a0and its gas component is called\u00a0<strong>natural gas<\/strong>, which is mostly made up of methane (CH<sub>4<\/sub>). As rocks such as shale, mudstone, or limestone lithify, increasing pressure and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> cause the oil and gas to be squeezed out and migrate from the <strong>source rock<\/strong> to a different rock unit higher in the rock column. Similar to the discussion of good\u00a0aquifers\u00a0in\u00a0<a href=\"https:\/\/opengeology.org\/textbook\/11-water\/\">Chapter 11<\/a>, if that rock is a sandstone, limestone, or other porous and permeable rock, and involved in a suitable stratigraphic or structural trapping process, then that rock can act as an<strong>\u00a0<\/strong>oil\u00a0and gas<strong> reservoir<\/strong>.<\/p>\n<figure id=\"attachment_4633\" aria-describedby=\"caption-attachment-4633\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Structural_Trap_Anticlinal.svg_.png\"><img class=\"wp-image-945 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Structural_Trap_Anticlinal.svg_-300x194.png\" alt=\"The rock layers are folded, and the petroleum is pooling toward the top of the fold.\" width=\"300\" height=\"194\"><\/a><figcaption id=\"caption-attachment-4633\" class=\"wp-caption-text\">A structural or anticline trap. The red on the image represents pooling petroleum. The green layer would be a permeable rock, and the yellow would be a reservoir rock.<\/figcaption><\/figure>\n<p>A\u00a0<strong>trap<\/strong> is a combination of a subsurface geologic structure, a porous and permeable rock, and an impervious layer that helps block oil and gas from moving further, which concentrates it for humans to extract later. A trap develops due to many different geologic situations. Examples include an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_504\">anticline<\/a> or domal structure, an impermeable salt <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_507\">dome<\/a>, or a fault bounded stratigraphic block, which is porous rock next to nonporous rock. The different traps have one thing in common: they pool fluid fossil fuels into a configuration in which extracting it is more likely to be profitable. Oil or gas in strata outside of a trap renders it less viable to extract.<\/p>\n<figure id=\"attachment_4634\" aria-describedby=\"caption-attachment-4634\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/TransgressionRegression.png\"><img class=\"wp-image-946 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/TransgressionRegression-300x199.png\" alt=\"Onlap is sediments moving toward the land. Offlap is moving away.\" width=\"300\" height=\"199\"><\/a><figcaption id=\"caption-attachment-4634\" class=\"wp-caption-text\">The rising sea levels of transgressions create onlapping sediments, regressions create offlapping.<\/figcaption><\/figure>\n<p><strong>Sequence stratigraphy<\/strong> is a branch of geology that studies sedimentary facies both horizontally and vertically and is devoted to understanding how sea level changes create organic-rich shallow marine muds, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonates<\/a>, and sands in areas that are close to each other. For example, shoreline environments may have beaches, lagoons, reefs, nearshore and offshore deposits, all next to each other. Beach sand, lagoonal and nearshore muds, and coral reef layers accumulate into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a> that include sandstones\u2014good reservoir rocks\u2014 next to mudstones, next to limestones, both of which are potential source rocks. As sea level either rises or falls, the shoreline\u2019s location changes, and the sand, mud, and reef locations shift with it (see the figure). This places oil and gas producing rocks, such as mudstones and limestones next to oil and gas reservoirs, such as sandstones and some limestones. Understanding how the lithology and the facies\/stratigraphic relationships interplay is very important in finding new petroleum resources. Using sequence stratigraphy as a model allows geologists to predict favorable locations of the source rock and reservoir.<\/p>\n<h4><span style=\"font-weight: 400\">Tar Sands<\/span><\/h4>\n<figure id=\"attachment_4635\" aria-describedby=\"caption-attachment-4635\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Tar_Sandstone_California.jpg\"><img class=\"wp-image-947 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tar_Sandstone_California-300x286.jpg\" alt=\"The sandstone is black with tar.\" width=\"300\" height=\"286\"><\/a><figcaption id=\"caption-attachment-4635\" class=\"wp-caption-text\">Tar sandstone from the Miocene Monterrey Formation of California.<\/figcaption><\/figure>\n<p><strong>Conventional<\/strong>\u00a0oil\u00a0and gas, which is pumped from a\u00a0reservoir, is not the only way to obtain hydrocarbons. There are a few fuel sources known as <strong>unconventional<\/strong>\u00a0petroleum\u00a0sources. However, they are becoming more important as conventional sources become scarce.\u00a0<strong>Tar sands<\/strong>, or oil sands, are sandstones that contain petroleum products that are highly viscous, like tar, and thus cannot be drilled and pumped out of the ground readily like conventional oil. This unconventional fossil fuel is <strong>bitumen<\/strong>, which can be pumped as a fluid only at very low recovery rates and only when heated or mixed with solvents. So, using steam and solvent injections or directly mining tar sands to process later are ways to extract the tar from the sands. Alberta, Canada is known to have the largest tar sand reserves in the world. Note: as with ores, an energy resource becomes uneconomic if the total extraction and processing costs exceed the extracted material\u2019s sales revenue. Environmental costs may also contribute to a resource becoming uneconomic.<\/p>\n<h4><span style=\"font-weight: 400\">Oil Shale<\/span><\/h4>\n<figure id=\"attachment_4636\" aria-describedby=\"caption-attachment-4636\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Production_of_oil_shale.png\"><img class=\"wp-image-948 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Production_of_oil_shale-300x195.png\" alt=\"Oil shale has dramatically increased starting around 1945.\" width=\"300\" height=\"195\"><\/a><figcaption id=\"caption-attachment-4636\" class=\"wp-caption-text\">Global production of Oil Shale, 1880-2010.<\/figcaption><\/figure>\n<p><strong>Oil shale<\/strong>, or\u00a0tight oil, is a fine-grained\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a>\u00a0that has significant petroleum\u00a0or\u00a0natural gas quantities locked tightly in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediment<\/a>.\u00a0Shale\u00a0has high\u00a0porosity\u00a0but very low permeability and is a common fossil fuel source rock. To extract the\u00a0oil directly from the shale, the material has to be\u00a0mined\u00a0and heated, which, like with tar sands, is expensive and typically has a negative environmental impact.<\/p>\n<h4><span style=\"font-weight: 400\">Fracking<\/span><\/h4>\n<figure id=\"attachment_4637\" aria-describedby=\"caption-attachment-4637\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/HydroFrac2.svg_.png\"><img class=\"wp-image-949 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HydroFrac2.svg_-300x175.png\" alt=\"The image shows fracking fluids cracking the rock, allowing methane to escape.\" width=\"300\" height=\"175\"><\/a><figcaption id=\"caption-attachment-4637\" class=\"wp-caption-text\">Schematic diagram of fracking.<\/figcaption><\/figure>\n<p>Another process used to extract the\u00a0oil\u00a0and gas from\u00a0shale\u00a0and other unconventional tight resources is called\u00a0<strong>hydraulic fracturing<\/strong>, better known as\u00a0<strong>fracking<\/strong>. In this method, high-pressure water, sand grains, and added chemicals are injected and pumped underground. Under high pressure, this creates and holds open\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fractures<\/a>\u00a0in the rocks, which help release the hard-to-access mostly\u00a0natural gas fluids. Fracking is more useful in tighter\u00a0sediments, especially\u00a0shale, which has a high\u00a0porosity\u00a0to store the hydrocarbons but low permeability to allow transmission of the hydrocarbons.\u00a0Fracking\u00a0has become controversial because its methods contaminate groundwater\u00a0and\u00a0induce seismic activity. This has created much controversy between public concerns, political concerns, and energy value.<\/p>\n<h3><b>16.2.2. Coal<\/b><\/h3>\n<figure id=\"attachment_4638\" aria-describedby=\"caption-attachment-4638\" style=\"width: 240px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Coal_Rank_USGS.png\"><img class=\"wp-image-950 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coal_Rank_USGS-240x300.png\" alt=\"The chart shows many different coal rankings\" width=\"240\" height=\"300\"><\/a><figcaption id=\"caption-attachment-4638\" class=\"wp-caption-text\">USGS diagram of different coal rankings.<\/figcaption><\/figure>\n<p><strong>Coal<\/strong>\u00a0comes from fossilized swamps, though some older\u00a0coal\u00a0deposits that predate\u00a0terrestrial\u00a0plants are presumed to come from algal buildups. Coal is chiefly carbon, hydrogen, nitrogen, sulfur, and oxygen, with minor amounts of other\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. As plant material is incorporated into\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a>, heat and pressure cause several changes that concentrate the fixed carbon, which is the coal\u2019s combustible portion. So, the more heat and pressure that\u00a0coal\u00a0undergoes, the greater is its carbon concentration and fuel value and the more desirable is the\u00a0coal.<\/p>\n<p>This is the general sequence of a swamp progressing through the various stages of coal formation and becoming more concentrated in carbon: Swamp =&gt; Peat =&gt; Lignite =&gt; Sub-bituminous =&gt; Bituminous =&gt; Anthracite =&gt; Graphite. As swamp materials collect on the swamp floor and are buried under accumulating materials, they first turn to peat.<\/p>\n<figure id=\"attachment_4639\" aria-describedby=\"caption-attachment-4639\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Peat_49302157252.jpg\"><img class=\"size-medium wp-image-951\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Peat_49302157252-300x225.jpg\" alt=\"A lump of peat.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-4639\" class=\"wp-caption-text\">Peat (also known as turf) consists of partially decayed organic matter. The Irish have long mined peat to be burned as fuel though this practice is now discouraged for environmental reasons.<\/figcaption><\/figure>\n<p>Peat itself is an economic fuel in some locations like the British Isles and Scandinavia. As <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1760\">lithification<\/a> occurs, peat turns to lignite. With increasing heat and pressure, lignite turns to sub-bituminous coal, bituminous coal, and then, in a process like metamorphism, anthracite. Anthracite is the highest metamorphic grade and most desirable coal since it provides the highest energy output. With even more heat and pressure driving out all the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1684\">volatiles<\/a> and leaving pure carbon, anthracite can become graphite.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_4640\" aria-describedby=\"caption-attachment-4640\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Coal_anthracite.jpg\"><img class=\"wp-image-4640 size-medium\" title=\"&quot;USGS\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coal_anthracite-1.jpg\" alt=\"It is very black and shiny.\" width=\"300\" height=\"281\"><\/a><figcaption id=\"caption-attachment-4640\" class=\"wp-caption-text\">Anthracite coal, the highest grade of coal.<\/figcaption><\/figure>\n<p>Humans have used coal for at least 6,000 years, mainly as a fuel source. Coal resources in Wales are often cited as a primary reason for Britain\u2019s rise, and later, for the United States\u2019 rise during the Industrial Revolution. According to the US Energy Information Administration, US coal production has decreased due to competing energy sources\u2019 cheaper prices and due to society recognizing its negative environmental impacts, including increased very fine-grained particulate matter as an air pollutant, greenhouse gases, acid rain, and heavy metal pollution. Seen from this perspective, the coal industry as a source of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossil<\/a> energy is unlikely to revive.<\/p>\n<p>As the world transitions away from fossil fuels including coal, and manufacturing seeks strong, flexible, and lighter materials than steel including carbon fiber for many applications, current research is exploring coal as a source of this carbon.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-110\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-110\" class=\"h5p-iframe\" data-content-id=\"110\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 16 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4902\" aria-describedby=\"caption-attachment-4902\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/16.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-953\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-4902\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 16.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">16.3 Mineral Resources<\/span><\/h2>\n<figure id=\"attachment_4641\" aria-describedby=\"caption-attachment-4641\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Mother_Lode_Gold_OreHarvard_mine_quartz-gold_vein.jpg\"><img class=\"wp-image-954 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Mother_Lode_Gold_OreHarvard_mine_quartz-gold_vein-300x209.jpg\" alt=\"The yellow gold is inside white quartz.\" width=\"300\" height=\"209\"><\/a><figcaption id=\"caption-attachment-4641\" class=\"wp-caption-text\">Gold-bearing quartz vein from California.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a>\u00a0resources, while principally\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a>, are generally placed\u00a0in two main categories:\u00a0<strong>metallic<\/strong>, which contain metals, and\u00a0<strong>nonmetallic<\/strong>, which contain other useful materials. Most\u00a0mining\u00a0has been traditionally focused on\u00a0extracting metallic\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. Human society has advanced significantly because we\u2019ve developed the\u00a0knowledge and technologies to yield metal from the Earth. This knowledge has allowed humans to build the machines, buildings, and monetary systems that dominate our world today. Locating and recovering these metals has been a key facet of geologic study since its inception. Every\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>\u00a0across the periodic table has specific applications in human civilization.\u00a0Metallic\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0mining\u00a0is the source of many of these\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>.<\/p>\n<h3><b>16.3.1. Types of Metallic Mineral Deposits<\/b><\/h3>\n<p>The various ways in which <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0and their associated\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>\u00a0concentrate to form\u00a0ore\u00a0deposits are too complex and numerous to fully review in this text. However, entire careers are built around them.\u00a0In the following section, we describe some of the more common deposit types along with their associated elemental concentrations and world class occurrences.<\/p>\n<h4><span style=\"font-weight: 400\">Magmatic Processes<\/span><\/h4>\n<figure id=\"attachment_4642\" aria-describedby=\"caption-attachment-4642\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/LayeredIntrusionChromitite_Bushveld_South_Africa.jpg\"><img class=\"wp-image-955 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LayeredIntrusionChromitite_Bushveld_South_Africa-300x211.jpg\" alt=\"The rock has several layers, with the dark layers being the ones with value.\" width=\"300\" height=\"211\"><\/a><figcaption id=\"caption-attachment-4642\" class=\"wp-caption-text\">Layered intrusion of dark chromium-bearing minerals, Bushveld Complex, South Africa<\/figcaption><\/figure>\n<p>When a magmatic body crystallizes and differentiates (see Chapter 4), it can cause certain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> to concentrate. <strong>Layered<\/strong>\u00a0<strong>intrusions<\/strong>, typically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1009\">ultramafic<\/a> to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a>, can host deposits that contain copper, nickel, platinum, palladium, rhodium, and chromium. The Stillwater Complex in Montana is an example of economic quantities of layered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a> intrusion. Associated deposit types can contain chromium or titanium-vanadium. The largest magmatic deposits in the world are the chromite deposits in the Bushveld <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">Igneous<\/a> Complex in South Africa. These rocks have an areal extent larger than the state of Utah. The chromite occurs in layers, which resemble sedimentary layers, except these layers occur within a crystallizing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_232\">magma chamber<\/a>.<\/p>\n<figure id=\"attachment_4909\" aria-describedby=\"caption-attachment-4909\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Elbai\u0308te_et_mica_Bre\u0301sil_1.jpg\"><img class=\"size-medium wp-image-4909\" src=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Elbai\u0308te_et_mica_Bre\u0301sil_1-300x199.jpg#fixme\" alt=\"The rock is mostly green and purple\" width=\"300\" height=\"199\"><\/a><figcaption id=\"caption-attachment-4909\" class=\"wp-caption-text\">This pegmatite contains lithium-rich green elbaite (a tourmaline) and purple lepidolite (a mica).<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Water and other\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1684\">volatiles<\/a>\u00a0that are not incorporated into\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0crystals when a\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>\u00a0crystallizes can become\u00a0concentrated\u00a0around the crystallizing\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>\u2019s margins. Ions in these hot fluids are very mobile and can form exceptionally large crystals.\u00a0Once crystallized, these large crystal masses are then called\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_996\">pegmatites<\/a><\/strong>. They form from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> fluids that are expelled from the solidifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> when nearly the entire <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> body has crystallized. In addition to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that are predominant in the main <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> mass, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_996\">pegmatite<\/a> bodies may also contain very large crystals of unusual <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that contain rare <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> like beryllium, lithium, tantalum, niobium, and tin, as well as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> like gold. Such <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_996\">pegmatites<\/a> are ores of these metals.<\/p>\n<figure id=\"attachment_4643\" aria-describedby=\"caption-attachment-4643\" style=\"width: 298px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/KimberlitePipe.jpg\"><img class=\"wp-image-956 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/KimberlitePipe-298x300.jpg\" alt=\"The pipe is deep and narrow.\" width=\"298\" height=\"300\"><\/a><figcaption id=\"caption-attachment-4643\" class=\"wp-caption-text\">Schematic diagram of a kimberlite pipe.<\/figcaption><\/figure>\n<p>An unusual magmatic process is a\u00a0<strong>kimberlite<\/strong> pipe, which is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_233\">conduit<\/a> that transports <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1009\">ultramafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> from within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> to the surface. Diamonds, which are formed at great temperatures and pressures of depth, are transported by a Kimberlite pipe to locations where they can be mined. The process that created these kimberlite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1009\">ultramafic<\/a> rocks is no longer common on Earth. Most known deposits are from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1242\">Eon<\/a>.<\/p>\n<h4><span style=\"font-weight: 400\">Hydrothermal Processes<\/span><\/h4>\n<figure id=\"attachment_4644\" aria-describedby=\"caption-attachment-4644\" style=\"width: 400px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Deep_sea_vent_chemistry_diagram.jpg\"><img class=\"wp-image-4644\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_sea_vent_chemistry_diagram-1.jpg\" alt=\"The diagram shows water going into the ground and coming out, with many different reactions.\" width=\"400\" height=\"233\"><\/a><figcaption id=\"caption-attachment-4644\" class=\"wp-caption-text\">The complex chemistry around mid-ocean ridges.<\/figcaption><\/figure>\n<p>Fluids rising from crystallizing magmatic bodies or that are heated by the\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_222\">geothermal gradient<\/a>\u00a0cause many geochemical reactions that form various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0deposits. The most active\u00a0hydrothermal\u00a0process today produces\u00a0<strong>volcanogenic massive sulfide<\/strong><strong>\u00a0<\/strong>(VMS) deposits, which form from black smoker hydrothermal chimney activity near <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> all over the world. They commonly contain copper, zinc, lead, gold, and silver when found at the surface. Evidence from around 7000 BC in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1244\">period<\/a> known as the Chalcolithic shows copper was among the earliest metals smelted by humans as means of obtaining higher temperatures were developed. The largest of these VMS deposits occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1270\">Precambrian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1244\">period<\/a> rocks. The Jerome deposit in central Arizona is a good example.<\/p>\n<p>Another deposit type that draws on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>-heated water is a\u00a0<strong>porphyry<\/strong> deposit. This is not to be confused with the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_994\">porphyritic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> texture, although the name is derived from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_994\">porphyritic<\/a> texture that is nearly always present in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> rocks associated with a porphyry deposit. Several types of porphyry deposits exist, such as porphyry copper, porphyry molybdenum, and porphyry tin. These deposits contain low-grade disseminated ore <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> closely associated with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1007\">intermediate<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_991\">intrusive<\/a> rocks that are present over a very large area. Porphyry deposits are typically the largest mines on Earth. One of the largest, richest, and possibly best studied mine in the world is Utah\u2019s Kennecott Bingham Canyon Mine. It\u2019s an open pit mine, which, for over 100 years, has produced several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> including copper, gold, molybdenum, and silver. Underground <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> replacement deposits produce lead, zinc, gold, silver, and copper. In the mine\u2019s past, the open pit predominately produced copper and gold from chalcopyrite and bornite. Gold only occurs in minor quantities in the copper-bearing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, but because the Kennecott Bingham Canyon Mine produces on such a large scale, it is one of the largest gold <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mines<\/a> in the US. In the future, this mine may produce more copper and molybdenum (molybdenite) from deeper underground mines.<\/p>\n<figure id=\"attachment_4645\" aria-describedby=\"caption-attachment-4645\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Morenci_Mine_2012.jpg\"><img class=\"wp-image-958 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Morenci_Mine_2012-300x200.jpg\" alt=\"The mine contains grey rocks, which are not enriched, and red rocks, which is where the enrichment occurs.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-4645\" class=\"wp-caption-text\">The Morenci porphyry is oxidized toward its top (as seen as red rocks in the wall of the mine), creating supergene enrichment.<\/figcaption><\/figure>\n<p>Most porphyry\u00a0copper deposits owe their high metal content, and hence, their economic value to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>\u00a0processes called<strong> supergene enrichment<\/strong> which occurs when the\u00a0deposit is uplifted, eroded, and exposed to\u00a0<strong>oxidation<\/strong>. This process <b>occur<\/b>r<b>ed<\/b> millions of years after the initial <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> intrusion and hydrothermal expulsion ends. When the deposit\u2019s upper pyrite-rich portion is exposed to rain, the pyrite in the oxidizing zone creates an extremely acid condition that dissolves copper out of copper\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>,\u00a0such as chalcopyrite, and converts the chalcopyrite to iron\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a>,\u00a0such as hematite or goethite. The copper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are carried downward in\u00a0water until they arrive at the\u00a0groundwater\u00a0table and an environment where the primary copper\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are converted\u00a0into secondary higher-copper content\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. Chalcopyrite (35% Cu) is converted to bornite (63% Cu), and ultimately, chalcocite (80% Cu).\u00a0Without this enriched zone, which is two to five times higher in copper content than the main deposit, most\u00a0porphyry\u00a0copper deposits would not be economic to mine.<\/p>\n<figure id=\"attachment_4646\" aria-describedby=\"caption-attachment-4646\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16.3_6_cm_grossular_calcite_augite_skarn.jpg\"><img class=\"wp-image-959 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.3_6_cm_grossular_calcite_augite_skarn-300x255.jpg\" alt=\"Calcite is blue, augite green, and garnet brown\/orange in this rock.\" width=\"300\" height=\"255\"><\/a><figcaption id=\"caption-attachment-4646\" class=\"wp-caption-text\">Garnet-augite skarn from Italy.<\/figcaption><\/figure>\n<p>If\u00a0limestone\u00a0or other calcareous sedimentary rocks are near the magmatic body, then another type of\u00a0ore\u00a0deposit called a\u00a0<strong>skarn<\/strong>\u00a0deposit forms. These\u00a0metamorphic\u00a0rocks form as\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>-derived, highly saline metalliferous fluids react with\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a>\u00a0rocks to create calcium-magnesium-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0like\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a>,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a>, and garnet, as well as high-grade\u00a0iron, copper, zinc\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>,\u00a0and gold. Intrusions that are genetically related to the intrusion that made the Kennecott Bingham Canyon deposit have also produced copper-gold skarns, which were\u00a0mined\u00a0by the early European settlers in Utah. When iron and\/or\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>\u00a0deposits undergo metamorphism, the\u00a0grain\u00a0size\u00a0commonly increases, which makes separating the\u00a0gangue\u00a0from the desired\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>\u00a0or\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0much easier.<\/p>\n<figure id=\"attachment_4647\" aria-describedby=\"caption-attachment-4647\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/GoldinPyrite.jpg\"><img class=\"wp-image-4647 size-medium\" title=\"&quot;<a\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/GoldinPyrite-1.jpg\" alt=\"The rock is red.\" width=\"300\" height=\"240\"><\/a><figcaption id=\"caption-attachment-4647\" class=\"wp-caption-text\">In this rock, a pyrite cube has dissolved (as seen with the negative \"corner\" impression in the rock), leaving behind small specks of gold.<\/figcaption><\/figure>\n<p><strong>Sediment-hosted disseminated gold<\/strong> deposits consist of low concentrations of microscopic gold as inclusions and disseminated atoms in pyrite crystals. These are formed via low-grade hydrothermal reactions, generally in the realm of diagenesis, that occur in certain rock types, namely muddy <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonates<\/a> and limey mudstones. This hydrothermal alteration is generally far removed from a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> source, but can be found in rocks situated with a high <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_222\">geothermal gradient<\/a>. The Mercur deposit in Utah\u2019s Oquirrh Mountains was this type\u2019s earliest locally mined deposit. There, almost a million ounces of gold was recovered between 1890 and 1917. In the 1960s, a metallurgical process using cyanide was developed for these low-grade ore types. These deposits are also called\u00a0<strong>Carlin-type<\/strong><strong>\u00a0<\/strong>deposits\u00a0because the disseminated deposit near Carlin, Nevada, is where the new technology was first applied and where the first definitive scientific studies were conducted. Gold was introduced into these deposits by\u00a0hydrothermal\u00a0fluids that reacted with silty calcareous rocks, removing\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a>, creating additional permeability, and adding silica and gold-bearing pyrite in the\u00a0pore\u00a0space between grains. The Betze-Post\u00a0mine\u00a0and the Gold Quarry\u00a0mine\u00a0on the Carlin Trend are two of the largest disseminated gold deposits in Nevada. Similar deposits, but not as large, have been found in China, Iran, and Macedonia.<\/p>\n<h4><span style=\"font-weight: 400\">Non-magmatic Geochemical Processes <\/span><\/h4>\n<figure id=\"attachment_4648\" aria-describedby=\"caption-attachment-4648\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/16.1_UraniumMineUtah.jpg\"><img class=\"wp-image-961 size-medium\" title=\"&quot;<a\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.1_UraniumMineUtah-300x225.jpg\" alt=\"A dark shaft runs into the mountain.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-4648\" class=\"wp-caption-text\">Underground uranium mine near Moab, Utah.<\/figcaption><\/figure>\n<p>Geochemical processes that occur at or near the surface without <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>\u2019s\u00a0aid also concentrate metals, but to a lesser degree than\u00a0hydrothermal\u00a0processes. One of the main reactions is\u00a0<strong>redox<\/strong>, short for reduction\/oxidation chemistry, which has to do with the amount of available oxygen in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1742\">system<\/a>. Places where oxygen is plentiful, as in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a> today, are considered oxidizing environments, while oxygen-poor places are considered reducing environments. Uranium deposits are an example of where redox concentrated the metal. Uranium is soluble in oxidizing groundwater environments and precipitates as uraninite when encountering reducing conditions. Many of the deposits across the Colorado Plateau, such as in \u00a0Moab, Utah, were formed by this method.<\/p>\n<p>Redox\u00a0reactions are also responsible for creating <strong>banded iron<\/strong><strong>\u00a0<\/strong><strong>formations<\/strong><strong>\u00a0<\/strong>(BIFs),<strong>\u00a0<\/strong>which are interbedded layers of iron\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a>\u2014hematite and magnetite,\u00a0chert, and\u00a0shale\u00a0beds. These deposits formed early in the Earth\u2019s history as the\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a>\u00a0was becoming oxygenated. Cycles of oxygenating iron-rich waters initiated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> of the\u00a0iron\u00a0beds. Because BIFs are generally\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1270\">Precambrian<\/a>\u00a0in age, happening at the event of atmospheric oxygenation, they are only found in some of the older exposed rocks in the United States, such as in Michigan\u2019s upper peninsula and northeast Minnesota.<\/p>\n<figure id=\"attachment_4649\" aria-describedby=\"caption-attachment-4649\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/MV-Type_and_clastic_sediment-hosted_lead-zinc_deposits.svg_.png\"><img class=\"wp-image-962 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MV-Type_and_clastic_sediment-hosted_lead-zinc_deposits.svg_-300x138.png\" alt=\"The are globally distributed.\" width=\"300\" height=\"138\"><\/a><figcaption id=\"caption-attachment-4649\" class=\"wp-caption-text\">Map of Mississippi-Valley type ore deposits.<\/figcaption><\/figure>\n<p>Deep, saline, connate fluids (trapped in pore spaces) within <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_510\">sedimentary basins<\/a>\u00a0may be highly metalliferous. When expelled outward and upward as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a> compacted, these fluids formed lead and zinc deposits in limestone by replacing or filling open spaces, such as caves and faults, and in sandstone by filling pore spaces. The most famous are called\u00a0<strong>Mississippi Valley-type<\/strong><strong>\u00a0<\/strong>deposits. Also known as\u00a0carbonate-hosted replacement\u00a0deposits, they are large deposits of galena and sphalerite lead and zinc\u00a0ores that form from hot fluids ranging from 100\u00b0C to 200\u00b0C (212\u00b0F to 392\u00b0F). Although they are named for occurring along the Mississippi\u00a0River\u00a0Valley in the US, they are found worldwide.<\/p>\n<p><strong>Sediment-hosted copper<\/strong><strong>\u00a0<\/strong>deposits occurring in\u00a0sandstones,\u00a0shales, and marls are enormous, and their contained resources are comparable to\u00a0porphyry\u00a0copper deposits. These deposits were most likely formed diagenetically by\u00a0groundwater\u00a0fluids in highly permeable rocks. Well-known examples are the Kupferschiefer in Europe, which has an areal coverage of &gt;500,000 Km<sup>2<\/sup>, (310,685.596mi) and the Zambian Copper Belt in Africa.<\/p>\n<figure id=\"attachment_4650\" aria-describedby=\"caption-attachment-4650\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Bauxite_with_unweathered_rock_core._C_021.jpg\"><img class=\"wp-image-4650 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bauxite_with_unweathered_rock_core._C_021-1.jpg\" alt=\"The outside of the rock is tan and weathered, the inside is grey.\" width=\"300\" height=\"195\"><\/a><figcaption id=\"caption-attachment-4650\" class=\"wp-caption-text\">A sample of bauxite. Note the unweathered igneous rock in the center.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_250\">Soils<\/a>\u00a0and\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0deposits that are exposed at the surface experience deep and intense\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>, which\u00a0can form surficial deposits.\u00a0<strong>Bauxite<\/strong>, an aluminum ore, is preserved in karst topography and laterites, which are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_250\">soils<\/a> formed in wet tropical environments. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_250\">Soils<\/a> containing aluminum concentrate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, and ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> and metamorphic rocks, undergo chemical weathering processes that concentrate the metals. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1009\">Ultramafic<\/a> rocks that undergo <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a> form nickel-rich <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_250\">soils<\/a>, and when the magnetite and hematite in banded iron formations undergo <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>, it forms goethite, a friable <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> that is easily mined for its iron content.<\/p>\n<h3><span style=\"font-weight: 400\">Surficial Physical Processes <\/span><\/h3>\n<figure id=\"attachment_4651\" aria-describedby=\"caption-attachment-4651\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/HeavyMineralsBeachSand.jpg\"><img class=\"wp-image-4651 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HeavyMineralsBeachSand-1.jpg\" alt=\"The tan rock has dark streaks of minerals.\" width=\"300\" height=\"205\"><\/a><figcaption id=\"caption-attachment-4651\" class=\"wp-caption-text\">Lithified heavy mineral sand (dark layers) from a beach deposit in India.<\/figcaption><\/figure>\n<p>At the Earth\u2019s surface, mass wasting\u00a0and moving water can cause hydraulic\u00a0sorting, which forces high-density\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> to concentrate. When these\u00a0minerals\u00a0are\u00a0concentrated\u00a0in\u00a0streams,\u00a0rivers,\u00a0and beaches, they are called\u00a0<strong>placer<\/strong>\u00a0deposits, and occur in modern sands and ancient lithified rocks.\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">Native<\/a>\u00a0gold,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a>\u00a0platinum,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1227\">zircon<\/a>, ilmenite, rutile, magnetite, diamonds, and other gemstones can be found in\u00a0placers. Humans have mimicked this natural process to recover gold manually by gold panning and by mechanized means such as dredging.<\/p>\n<h3><b>16.3.2. Environmental Impacts of Metallic Mineral Mining<\/b><\/h3>\n<figure id=\"attachment_4652\" aria-describedby=\"caption-attachment-4652\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Rio_tinto_river_CarolStoker_NASA_Ames_Research_Center.jpg\"><img class=\"wp-image-965 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rio_tinto_river_CarolStoker_NASA_Ames_Research_Center-300x225.jpg\" alt=\"The water in the river is bright orange.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-4652\" class=\"wp-caption-text\">Acid mine drainage in the Rio Tinto, Spain.<\/figcaption><\/figure>\n<p>Metallic\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0mining\u2019s\u00a0primary impact comes from the\u00a0mining\u00a0itself, including disturbing the land surface, covering landscapes with tailings impoundments, and increasing\u00a0mass wasting\u00a0by accelerating\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1755\">erosion<\/a>. In addition, many metal deposits contain pyrite, an uneconomic\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>, that when\u00a0placed on waste dumps, generates\u00a0<strong>acid rock drainage<\/strong>\u00a0(ARD)<strong>\u00a0<\/strong>during <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>. In oxygenated water, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfides<\/a> such as pyrite react and undergo complex reactions to release metal ions and hydrogen ions, which lowers pH to highly acidic levels. Mining and processing of mined materials typically increase the surface area to volume ratio in the material, causing chemical reactions to occur even faster than would occur naturally. If not managed properly, these reactions lead to acidic streams and groundwater plumes that carry dissolved toxic metals. In mines where limestone is a waste rock or where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> or dolomite are present, their acid neutralizing potential helps reduce acid rock drainage. Although this is a natural process too, it is very important to isolate mine dumps and tailings from oxygenated water, both to prevent the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfides<\/a> from dissolving and subsequently percolating the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">sulfate<\/a>-rich water into waterways. Industry has taken great strides to prevent contamination in recent decades, but earlier mining projects are still causing problems with local ecosystems.<\/p>\n<h3><strong>16.3.3. Nonmetallic Mineral\u00a0Deposits<\/strong><\/h3>\n<figure id=\"attachment_4653\" aria-describedby=\"caption-attachment-4653\" style=\"width: 225px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/CarraraMarblequarry.jpg\"><img class=\"wp-image-966 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CarraraMarblequarry-225x300.jpg\" alt=\"The image shows a hillside with blocks of marble removed.\" width=\"225\" height=\"300\"><\/a><figcaption id=\"caption-attachment-4653\" class=\"wp-caption-text\">Carrara marble quarry in Italy, source to famous sculptures like Michelangelo's David.<\/figcaption><\/figure>\n<p>While receiving much less attention, nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> resources, also known as industrial <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, are just as vital to ancient and modern society as metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. The most basic is building stone. Limestone, travertine, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a>, slate, and marble are common building stones and have been quarried for centuries. Even today, building stones from slate roof tiles to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a> countertops are very popular. Especially pure limestone is ground up, processed, and reformed as plaster, cement, and concrete. Some nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> resources are not <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> specific; nearly any rock or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> can be used. This is generally called aggregate, which is used in concrete, roads, and foundations. Gravel is one of the more common aggregates.<\/p>\n<h4><span style=\"font-weight: 400\">Evaporites<\/span><\/h4>\n<figure id=\"attachment_4654\" aria-describedby=\"caption-attachment-4654\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Bonneville_Salt_Flats_Utah.jpg\"><img class=\"wp-image-4654 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bonneville_Salt_Flats_Utah-1.jpg\" alt=\"The ground is white and flat for a long distance.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-4654\" class=\"wp-caption-text\">Salt-covered plain known as the Bonneville Salt Flats, Utah.<\/figcaption><\/figure>\n<p><strong>Evaporite<\/strong><strong>\u00a0<\/strong>deposits\u00a0form in restricted basins where water evaporates faster than it recharges, such as the Great Salt Lake in Utah, or the Dead Sea, which borders Israel and Jordan. As the waters evaporate, soluble\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u00a0are\u00a0concentrated\u00a0and become supersaturated, at which point they\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitate<\/a>\u00a0from the now highly-saline waters. If these conditions persist for long stretches, thick rock salt, rock\u00a0gypsum,\u00a0and other\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u00a0deposits accumulate (see Chapter 5).<\/p>\n<figure id=\"attachment_4655\" aria-describedby=\"caption-attachment-4655\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Hanksite.jpg\"><img class=\"wp-image-968 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hanksite-300x200.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-4655\" class=\"wp-caption-text\">Hanksite, Na22K(SO4)9(CO3)2Cl, one of the few minerals that is considered a carbonate and a sulfate<\/figcaption><\/figure>\n<p>Evaporite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, such as halite, are used in our food as common table salt. Salt was a vitally important food preservative and economic resource before refrigeration was developed. While still used in food, halite is now mainly mined as a chemical agent, water softener, or road de-icer. Gypsum is a common nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> used as a building material; it is the main component in dry wall. It is also used as a fertilizer. Other evaporites include sylvite\u2014potassium chloride, and bischofite\u2014magnesium chloride, both of which are used in agriculture, medicine, food processing, and other applications. Potash, a group of highly soluble potassium-bearing evaporite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, is used as a fertilizer. In hyper-arid locations, even more rare and complex evaporites, like borax, trona, ulexite, and hanksite are mined. They can be found in places such as Searles Dry Lake and Death Valley, California, and in the Green River Formation\u2019s ancient evaporite deposits in Utah and Wyoming.<\/p>\n<h4><span style=\"font-weight: 400\">Phosphorus<\/span><\/h4>\n<figure id=\"attachment_4656\" aria-describedby=\"caption-attachment-4656\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Apatite-CaF-280343.jpg\"><img class=\"wp-image-4656 size-medium\" title=\"&quot;Rob\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Apatite-CaF-280343-1.jpg\" alt=\"The crystal is hexagonal and light green.\" width=\"300\" height=\"267\"><\/a><figcaption id=\"caption-attachment-4656\" class=\"wp-caption-text\">Apatite from Mexico.<\/figcaption><\/figure>\n<p>Phosphorus is an essential <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> that occurs in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> apatite, which is found in trace amounts in common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> rocks. Phosphorite rock, which is formed in sedimentary environments in the ocean, contains abundant apatite and is mined to make fertilizer. Without phosphorus, life as we know it is not possible. Phosphorous is an important component of bone and DNA. Bone <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1001\">ash<\/a> and guano are natural sources of phosphorus.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<figure id=\"attachment_4903\" aria-describedby=\"caption-attachment-4903\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/16.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-970\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/16.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-4903\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 16.3 via this QR Code.<\/figcaption><\/figure>\n<h1>Summary<\/h1>\n<p>Energy and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> resources are vital to modern society, and it is the role of the geologist to locate these resources for human benefit. As environmental concerns have become more prominent, the value of the geologist has not decreased, as they are still vital in locating the deposits and identifying the least <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_991\">intrusive<\/a> methods of extraction.<\/p>\n<p>Energy resources are general grouped as being <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a>. Geologists can aid in locating the best places to exploit <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1740\">renewable<\/a> resources (e.g. locating a dam), but are commonly tasked with finding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1739\">nonrenewable<\/a> fossil fuels. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a> resources are also grouped in two categories: metallic and nonmetallic. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> have a wide variety of processes that concentrate them to economic levels, and are usually mined via surface or underground methods.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<figure id=\"attachment_4904\" aria-describedby=\"caption-attachment-4904\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Ch.16-Review-QR-Code.png\"><img class=\"size-thumbnail wp-image-971\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.16-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-4904\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 16 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<ol>\n<li style=\"text-align: left\">Ague, Jay James, and George H. Brimhall. 1989. \u201cGeochemical Modeling of Steady State Fluid Flow and Chemical Reaction during Supergene Enrichment of Porphyry Copper Deposits.\u201d <em>Economic Geology and the Bulletin of the Society of Economic Geologists<\/em> 84 (3). economicgeology.org: 506\u201328.<\/li>\n<li style=\"text-align: left\">Arndt, N. T. 1994. \u201cChapter 1 Archean Komatiites.\u201d In <em>Developments in Precambrian Geology<\/em>, edited by K.C. Condie, 11:11\u201344. Elsevier.<\/li>\n<li style=\"text-align: left\">B\u00e1rdossy, Gy\u00f6rgy, and Gerardus Jacobus Johannes Aleva. 1990. <em>Lateritic Bauxites<\/em>. Vol. 27. Elsevier Science Ltd.<\/li>\n<li style=\"text-align: left\">Barrie, C. T. 1999. \u201cVolcanic-Associated Massive Sulfide Deposits: Processes and Examples in Modern and Ancient Settings.\u201d Reviews in Economic Geology, v. 8. https:\/\/www.researchgate.net\/profile\/Michael_Perfit\/publication\/241276560_Geologic_petrologic_and_geochemical_relationships_between_magmatism_and_massive_sulfide_mineralization_along_the_eastern_Galapagos_Spreading_Center\/links\/02e7e51c8707bbfe9c000000.pdf.<\/li>\n<li style=\"text-align: left\">Barrie, L. A., and R. M. Hoff. 1984. \u201cThe Oxidation Rate and Residence Time of Sulphur Dioxide in the Arctic Atmosphere.\u201d <em>Atmospheric Environment<\/em> 18 (12). Elsevier: 2711\u201322.<\/li>\n<li style=\"text-align: left\">Bauquis, Pierre-Ren\u00e9. 1998. \u201cWhat Future for Extra Heavy Oil and Bitumen: The Orinoco Case.\u201d In <em>Paper Presented by TOTAL at the World Energy Congress<\/em>, 13:18.<\/li>\n<li style=\"text-align: left\">Belloc, H. 1913. <em>The Servile State<\/em>. T.N. Foulis.<\/li>\n<li style=\"text-align: left\">Blander, M., S. Sinha, A. Pelton, and G. Eriksson. 2011. \u201cCalculations of the Influence of Additives on Coal Combustion Deposits.\u201d <em>Argonne National Laboratory, Lemont, Illinois<\/em>. enersol.pk, 315.<\/li>\n<li style=\"text-align: left\">Boudreau, Alan E. 2016. \u201cThe Stillwater Complex, Montana--Overview and the Significance of Volatiles.\u201d <em>Mineralogical Magazine<\/em> 80 (4). Mineralogical Society: 585\u2013637.<\/li>\n<li style=\"text-align: left\">Bromfield, C. S., A. J. Erickson, M. A. Haddadin, and H. H. Mehnert. 1977. \u201cPotassium-Argon Ages of Intrusion, Extrusion, and Associated Ore Deposits, Park City Mining District, Utah.\u201d <em>Economic Geology and the Bulletin of the Society of Economic Geologists<\/em> 72 (5). economicgeology.org: 837\u201348.<\/li>\n<li style=\"text-align: left\">Brown, Valerie J. 2007. \u201cIndustry Issues: Putting the Heat on Gas.\u201d Environmental Health Perspectives 115 (2). ncbi.nlm.nih.gov: A76.<\/li>\n<li style=\"text-align: left\">Cabri, Louis J., Donald C. Harris, and Thorolf W. Weiser. 1996. \u201cMineralogy and Distribution of Platinum-Group Mineral (PGM) Placer Deposits of the World.\u201d <em>Exploration and Mining Geology<\/em> 2 (5). infona.pl: 73\u2013167.<\/li>\n<li style=\"text-align: left\">Crutzen, Paul J., and Jos Lelieveld. 2001. \u201cHuman Impacts on Atmospheric Chemistry.\u201d <em>Annual Review of Earth and Planetary Sciences<\/em> 29 (1). 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Cambridge University Press.<\/li>\n<li style=\"text-align: left\">Youngquist, Walter. 1998. \u201cShale Oil--The Elusive Energy.\u201d <em>Hubbert Center Newsletter<\/em> 4.<\/li>\n<\/ol>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_976\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_976\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1023\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1023\"><div tabindex=\"-1\"><p>Place where oceanic-oceanic subduction causes volcanoes to form on an overriding oceanic plate, making a chain of active volcanoes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1929\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1929\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1008\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1008\"><div tabindex=\"-1\"><p>Mix of sediments that form as a subducting plate descends and the overriding plate scrapes material and material is added.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1664\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1664\"><div tabindex=\"-1\"><p>Dunes that form semicircular shapes due to anchoring vegetation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1789\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1789\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1013\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1013\"><div tabindex=\"-1\"><p>A chain of volcanic activity, typically in a curved pattern, rising from a subduction zone. The arc is on the overriding plate, typically a few hundred kilometers from the trench, but parallel to the trench.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2001\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2001\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1708\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1708\"><div tabindex=\"-1\"><p>The measure of the amount of circular or elliptical nature of the Earth's orbit.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1659\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1659\"><div tabindex=\"-1\"><p>Planar flow of water over land surfaces.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_986\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_986\"><div tabindex=\"-1\"><p>A property of a solid, such that when a force is applied, the solid flows, stretches, or bends along with the force, instead of cracking or breaking. For example, many plastics are ductile.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1787\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1787\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2000\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2000\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_234\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_234\"><div tabindex=\"-1\"><figure id=\"attachment_2752\" aria-describedby=\"caption-attachment-2752\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Cristales_cueva_de_Naica.jpg\"><img class=\"wp-image-2752 size-large\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/Cristales_cueva_de_Naica-1024x683-1.jpg\" alt=\"The crystals are huge!\" width=\"1024\" height=\"683\"><\/a><figcaption id=\"caption-attachment-2752\" class=\"wp-caption-text\">These selenite (gypsum) crystals, found in The Cave of the Crystals in Naica, Mexico, has some of the largest minerals ever found. The largest crystal found here is 39 feet (12 meters) and 55 tones.<\/figcaption><\/figure>\n<h1>3 Minerals<\/h1>\n<p><strong>KEY<\/strong><b> CONCEPTS<\/b><\/p>\n<p><b>At the end of this chapter, students should be able to:<\/b><\/p>\n<ul>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Define <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the basic structure of the atom.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Derive basic atomic information from the Periodic Table of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">Elements<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonding<\/a> related to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the main ways <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> form.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedron<\/a> and how it forms common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">List common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">sulfate<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> groups.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> using physical properties and identification tables. <\/span><\/li>\n<\/ul>\n<p>The term \u201c<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u201d as used in nutrition labels and pharmaceutical products is not the same as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> in a geological sense. In geology, the classic definition of a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a><\/strong> is: 1) naturally occurring, 2) inorganic, 3) solid at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>, 4) regular crystal structure, and 5) defined chemical composition. Some natural substances technically should not be considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, but are included by exception. For example, water and mercury are liquid at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>. Both are considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> because they were classified before the room-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> rule was accepted as part of the definition. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a> is quite often formed by organic processes, but is considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> because it is widely found and geologically important. Because of these discrepancies, the International Mineralogical Association in 1985 amended the definition to: \u201cA <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> is an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> or chemical compound that is normally crystalline and that has been formed as a result of geological processes.\u201d This means that the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> in the shell of a clam is not considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>. But once that clam shell undergoes burial, diagenesis, or other geological processes, then the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> is considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>. Typically, substances like coal, pearl, opal, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_999\">obsidian<\/a> that do not fit the definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> are called mineraloids.<\/p>\n<p>A <strong>rock<\/strong> is a substance that contains one or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> or mineraloids. As is discussed in later chapters, there are three types of rocks composed of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> (rocks crystallizing from molten material), sedimentary (rocks composed of products of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_251\">mechanical weathering<\/a> (sand, gravel, etc.) and chemical weathering (things <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitated<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a>), and metamorphic (rocks produced by alteration of other rocks by heat and pressure.<\/p>\n<h2><span style=\"font-weight: 400\">3.1 Chemistry of Minerals<\/span><\/h2>\n<p>Rocks are composed of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that have a specific chemical composition.\u00a0 To understand <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> chemistry, it is essential to examine the fundamental unit of all matter, the atom.<\/p>\n<h3><b>3.1.1 The Atom<\/b><\/h3>\n<figure id=\"attachment_2753\" aria-describedby=\"caption-attachment-2753\" style=\"width: 283px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.1-Electron_cloud_model_of_atom.jpg\"><img class=\"size-medium wp-image-2753\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/03.1-Electron_cloud_model_of_atom-283x300-1.jpg\" alt=\"Image of atom with defined nucleus and electrons surrounding it in a cloud with concentrations of electrons in energy shells\" width=\"283\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2753\" class=\"wp-caption-text\">Electron cloud model of the atom<\/figcaption><\/figure>\n<p>Matter is made of atoms. Atoms consists of subatomic particles\u2014<strong>protons<\/strong>, <strong>neutrons<\/strong>, and <strong>electrons<\/strong>. A simple model of the atom has a central nucleus composed of protons, which have positive charges, and neutrons which have no charge. A cloud of negatively charged electrons surrounds the nucleus, the number of electrons equaling the number of protons thus balancing the positive charge of the protons for a neutral atom. Protons and neutrons each have a mass number of 1. The mass of an electron is less than\u00a01\/1000<sup>th<\/sup>\u00a0that of a proton or neutron, meaning most of the atom\u2019s mass is in the nucleus.<\/p>\n<h3><b>3.1.2 Periodic Table of the Elements<\/b><\/h3>\n<p>Matter is composed of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> which are atoms that have a specific number of protons in the nucleus. This number of protons is called the <strong>Atomic Number<\/strong> for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>. For example, an oxygen atom has 8 protons and an iron atom has 26 protons. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> cannot be broken down chemically into a simpler form and retains unique chemical and physical properties. Each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> behaves in a unique manner in nature. This uniqueness led scientists to develop a periodic table of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>, a tabular arrangement of all known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> listed in order of their atomic number.<\/p>\n<figure id=\"attachment_2754\" aria-describedby=\"caption-attachment-2754\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Periodic_Table-02-scaled.jpg\"><img class=\"size-large wp-image-2754\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/Periodic_Table-02-1024x795-1.jpg\" alt=\"The Periodic Table of the Elements showing all elements with their chemical symbols, atomic weight, and atomic number.\" width=\"1024\" height=\"795\"><\/a><figcaption id=\"caption-attachment-2754\" class=\"wp-caption-text\">The Periodic Table of the Elements<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">The first arrangement of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> into a periodic table was done by Dmitri Mendeleev in 1869 using the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> known at the time<\/span><span style=\"font-weight: 400\">. In the periodic table, each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> has a chemical symbol, name, atomic number, and atomic mass. The chemical symbol is an abbreviation for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>, often derived from a Latin or Greek name for the substance<\/span><span style=\"font-weight: 400\">. The atomic number is the number of protons in the nucleus. The atomic mass is the number of protons and neutrons in the nucleus, each with a mass number of one. Since the mass of electrons is so much less than the protons and neutrons, the atomic mass is effectively the number of protons plus neutrons. <\/span><\/p>\n<figure id=\"attachment_2755\" aria-describedby=\"caption-attachment-2755\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3a_Formation_of_Carbon14_from_Nitrogen14.jpg\"><img class=\"size-medium wp-image-2755\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/3.3a_Formation_of_Carbon14_from_Nitrogen14-300x123-1.jpg\" alt=\"\" width=\"300\" height=\"123\"><\/a><figcaption id=\"caption-attachment-2755\" class=\"wp-caption-text\">Formation of Carbon 14 from Nitrogen 14<\/figcaption><\/figure>\n<p>The atomic mass of natural <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> represents an average mass of the atoms comprising that substance in nature and is usually not a whole number as seen on the periodic table, meaning that an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> exists in nature with atoms having different numbers of neutrons. The differing number of neutrons affects the mass of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> in nature and the atomic mass number represents this average. This gives rise to the concept of\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1779\">isotope<\/a><strong>.\u00a0<\/strong><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1779\">Isotopes<\/a> <\/strong>are forms of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> with the same number of protons but different numbers of neutrons. There are usually several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1779\">isotopes<\/a> for a particular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>. For example, 98.9% of carbon atoms have 6 protons and 6 neutrons. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1779\">isotope<\/a> of carbon is called carbon-12 (<sup>12<\/sup>C). A few carbon atoms, carbon-13 (<sup>13<\/sup>C), have 6 protons and 7 neutrons. A trace amount of carbon atoms, carbon-14 (<sup>14<\/sup>C), has 6 protons and 8 neutrons.<\/p>\n<figure id=\"attachment_2756\" aria-describedby=\"caption-attachment-2756\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/elemental-composition-crust.jpg\"><img class=\"size-medium wp-image-2756\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/elemental-composition-crust-300x277-1.jpg\" alt=\"Oxygen and silicon make up 3\/4ths of the chart.\" width=\"300\" height=\"277\"><\/a><figcaption id=\"caption-attachment-2756\" class=\"wp-caption-text\">Element abundance pie chart for Earth's crust by Callan Bentley.<\/figcaption><\/figure>\n<p>Among the 118 known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>, the heaviest are fleeting human creations known only in high energy particle accelerators, and they decay rapidly. The heaviest naturally occurring <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> is uranium, atomic number 92. The eight most abundant elements in Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a> are shown in Table 1<span style=\"font-weight: 400\">. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> are found in the most common rock forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<table style=\"height: 135px\">\n<tbody>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">Element<\/a><\/b><\/td>\n<td style=\"height: 15px;width: 134.797px\"><b>Symbol<\/b><\/td>\n<td style=\"height: 15px;width: 237.703px\"><b>Abundance %<\/b><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Oxygen<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">O<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">47%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Silicon<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Si<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">28%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Aluminum<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Al<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">8%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Iron<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Fe<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">5%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Calcium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Ca<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">4%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Sodium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Na<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Potassium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">K<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Magnesium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">Mg<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">2%<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em style=\"font-size: 16px;font-weight: 400\">Table 1. Eight Most Abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">Elements<\/a> in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">Continental Crust<\/a> % by weight (source:\u00a0<a href=\"https:\/\/pubs.usgs.gov\/circ\/1953\/0285\/report.pdf\">USGS<\/a>). All other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> are less than 1%.<\/em><\/p>\n<h3><b>3.1.3 Chemical Bonding<\/b><\/h3>\n<figure id=\"attachment_2757\" aria-describedby=\"caption-attachment-2757\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/H2O_2D_labelled.svg_.png\"><img class=\"wp-image-145 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/H2O_2D_labelled.svg_-300x131.png\" alt=\"The hydrogen atoms are on one side, about 105\u00b0 apart.\" width=\"300\" height=\"131\"><\/a><figcaption id=\"caption-attachment-2757\" class=\"wp-caption-text\">A model of a water molecule, showing the bonds between the hydrogen and oxygen.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Most substances on Earth are compounds containing multiple <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. Chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonding<\/a> describes how these atoms attach with each other to form compounds, such as sodium and chlorine combining to form NaCl, common table salt. Compounds that are held together by\u00a0<\/span>chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> are called molecules. Water is a compound of hydrogen and oxygen in which two hydrogen atoms are covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> with one oxygen making the water molecule. The oxygen we breathe is formed when one oxygen atom covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> with another oxygen atom to make the molecule O<sub>2<\/sub>. The subscript 2 in the chemical formula indicates the molecule contains two atoms of oxygen.<\/p>\n<p>Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are also compounds of more than one <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>. The common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> has the chemical formula CaCO<sub>3<\/sub> indicating the molecule consists of one calcium, one carbon, and three oxygen atoms.\u00a0In <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, one carbon and three oxygen atoms are held together by covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> to form a <strong>molecular ion<\/strong>, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a>, which has a negative charge. Calcium as an <strong>ion<\/strong> has a positive charge of plus two. The two oppositely charged ions attract each other and combine to form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, CaCO3. The name of the chemical compound is calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a>, where calcium is Ca and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> refers to the molecular ion CO<sub>3<\/sub><sup>-2<\/sup>.<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> has the chemical formula (Mg,Fe)<sub>2<\/sub>SiO<sub>4<\/sub>, in which one silicon and four oxygen atoms are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> with two atoms of either magnesium or iron.\u00a0The comma between iron (Fe) and magnesium (Mg) indicates the two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> can occupy the same location in the crystal structure and substitute for one another.<\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.1 Valence and Charge<\/span><\/i><\/h4>\n<p><span style=\"font-weight: 400\">The electrons around the atom\u2019s nucleus are located in shells representing different energy levels. The outermost shell is called the <strong>valence shell<\/strong>. Electrons in the valence shell are involved in chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonding<\/a>. In 1913, Niels Bohr proposed a simple model of the atom that states atoms are more stable when their outermost shell is full<\/span><span style=\"font-weight: 400\">. Atoms of most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> thus tend to gain or lose electrons so the outermost or valence shell is full. In Bohr\u2019s model, the innermost shell can have a maximum of two electrons and the second and third shells can have a maximum of eight electrons. <\/span>When the innermost shell is the valence shell, as in the case of hydrogen and helium, it obeys the octet rule when it is full with two electrons. For <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in higher rows, the octet rule of eight electrons in the valence shell applies.<\/p>\n<figure id=\"attachment_2758\" aria-describedby=\"caption-attachment-2758\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.4_Carbon_dioxide_3D_ball.png\"><img class=\"wp-image-2758 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.4_Carbon_dioxide_3D_ball-300x213-1.png\" alt=\"Carbon dioxide molecule with a carbon ion in the center and two oxygen ions on either side, each sharing two electrons with the carbon.\" width=\"300\" height=\"213\"><\/a><figcaption id=\"caption-attachment-2758\" class=\"wp-caption-text\">The carbon dioxide molecule. Since Oxygen is -2 and Carbon is +4, the two oxygens bond to the carbon to form a neutral molecule.<\/figcaption><\/figure>\n<p>The rows in the periodic table present the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in order of atomic number and the columns organize <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> with similar characteristics, such as the same number of electrons in their valence shells. Columns are often labeled from left to right with Roman numerals I to VIII, and Arabic numerals 1 through 18. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in columns I and II have 1 and 2 electrons in their respective valence shells and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in columns VI and VII have 6 and 7 electrons in their respective valence shells.<\/p>\n<p><span style=\"font-weight: 400\">In row 3 and column I, sodium (Na) has 11 protons in the nucleus and 11 electrons in three shells\u20142 electrons in the inner shell, 8 electrons in the second shell, and 1 electron in the valence shell. To maintain a full outer shell of 8 electrons per the octet rule, sodium readily gives up that 1 electron so there are 10 total electrons. With 11 positively charged protons in the nucleus and 10 negatively charged electrons in two shells, sodium when forming chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> is an ion with an overall net charge of +1<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<p><span style=\"font-weight: 400\">All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in column I have a single electron in their valence shell and a valence of 1.\u00a0<\/span>These other column I <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> also readily give up this single valence electron and thus become ions with a +1 charge. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">Elements<\/a> in column II readily give up 2 electrons and end up as ions with a charge of +2. Note that elements in columns I and II which readily give up their valence electrons, often form bonds with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in columns VI and VII which readily take up these electrons. \u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">Elements<\/a> in columns 3 through 15 are usually involved in covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonding<\/a>. The last column 18 (VIII) contains the <strong>noble gases<\/strong>. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> are chemically inert because the valence shell is already full with 8 electrons, so they do not gain or lose electrons. An example is the noble gas helium which has 2 valence electrons in the first shell. Its valence shell is therefore full. All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in column VIII possess full valence shells and do not form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>.<\/p>\n<p><span style=\"font-weight: 400\">As seen above, an atom with a net positive or negative charge as a result of gaining or losing electrons is called an <strong>ion<\/strong>. In general the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> on the left side of the table lose electrons and become positive ions, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cations<\/a> because they are attracted to the cathode in an electrical device. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> on the right side tend to gain electrons. These are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1782\">anions<\/a> because they are attracted to the anode in an electrical device. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> in the center of the periodic table, columns 3 through 15, do not consistently follow the octet rule. These are called transition <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. A common example is iron, which has a +2 or +3 charge depending on the oxidation state of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>. Oxidized Fe<sup>+3<\/sup> carries a +3 charge and reduced Fe<sup>+2<\/sup> is +2. These two different oxidation states of iron often impart dramatic colors to rocks containing their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>\u2014the oxidized form producing red colors and the reduced form producing green.<\/span><\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.2\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Ionic Bonding<\/span><\/i><\/h4>\n<figure id=\"attachment_2759\" aria-describedby=\"caption-attachment-2759\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03-Sodium-chloride-3D-ionic.png\"><img class=\"size-medium wp-image-2759\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03-Sodium-chloride-3D-ionic-300x284-1.png\" alt=\"Image of crystal model of halite with ions of sodium and chlorine arranged in a cubic structure.\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2759\" class=\"wp-caption-text\">Cubic arrangement of Na and Cl in Halite<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a>, also called electron-transfer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a>, are formed by the electrostatic attraction between atoms having opposite charges. Atoms of two opposite charges attract each other electrostatically and form an <strong>ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a><\/strong> in which the positive ion transfers its electron (or electrons) to the negative ion which takes them up. Through this transfer both atoms thus achieve a full valence shell.\u00a0<\/span>For example one atom of sodium (Na<sup>+1<\/sup>) and one atom of chlorine (Cl<sup>-1<\/sup>) form an ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> to make the compound sodium chloride (NaCl). This is also known as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> halite or common table salt. Another example is calcium (Ca<sup>+2<\/sup>) and chlorine (Cl<sup>-1<\/sup>) combining to make the compound calcium chloride (CaCl<sub>2<\/sub>). The subscript 2 indicates two atoms of chlorine are ionically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> to one atom of calcium.<\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.3\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Covalent <\/span><\/i><i><span style=\"font-weight: 400\">Bonding<\/span><\/i><\/h4>\n<figure id=\"attachment_2760\" aria-describedby=\"caption-attachment-2760\" style=\"width: 249px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Covalent.svg_.png\"><img class=\"size-medium wp-image-2760\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Covalent.svg_-249x300-1.png\" alt=\"Each atom is sharing electrons.\" width=\"249\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2760\" class=\"wp-caption-text\">Methane molecule<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> are usually formed between a <strong>metal<\/strong> and a <strong>nonmetal<\/strong>. Another type, called a covalent or electron-sharing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a>, commonly occurs between nonmetals. Covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> share electrons between ions to complete their valence shells. For example, oxygen (atomic number 8) has 8 electrons\u20142 in the inner shell and 6 in the valence shell. Gases like oxygen often form diatomic molecules by sharing valence electrons. In the case of oxygen, two atoms attach to each other and share 2 electrons to fill their valence shells to become the common oxygen molecule we breathe (O<sub>2<\/sub>). Methane (CH<sub>4<\/sub>) is another covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> gas. The carbon atom needs 4 electrons and each hydrogen needs 1. Each hydrogen shares its electron with the carbon to form a molecule as shown in the figure.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-18\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-18\" class=\"h5p-iframe\" data-content-id=\"18\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3754\" aria-describedby=\"caption-attachment-3754\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-149\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3754\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 28px\">3.2 Formation of Minerals<\/span><\/h2>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> form when atoms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> together in a crystalline arrangement. Three main ways this occurs in nature are: 1) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> directly from an aqueous (water) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a> with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> change, 2) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1752\">crystallization<\/a> from a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> change, and 3) biological <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> by the action of organisms. <\/span><\/p>\n<h3><b> 3.2.1 Precipitation from aqueous solution<\/b><\/h3>\n<figure id=\"attachment_2761\" aria-describedby=\"caption-attachment-2761\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5_Hard_Water_Calcification.jpg\"><img class=\"size-medium wp-image-2761\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.5_Hard_Water_Calcification-300x200-1.jpg\" alt=\"Encrusted calcium carbonate (lime) deposits on faucent\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2761\" class=\"wp-caption-text\">Calcium carbonate deposits from hard water<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">Solutions<\/a> consist of ions or molecules, known as solutes, dissolved in a medium or solvent. In nature this solvent is usually water. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> can be dissolved in water, such as halite or table salt, which has the composition sodium chloride, NaCl. The Na<sup>+1<\/sup> and Cl<sup>-1<\/sup> ions separate and disperse into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a>.<\/p>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">Precipitation<\/a><\/strong> is the reverse process, in which ions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a> come together to form solid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">Precipitation<\/a> is dependent on the concentration of ions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a> and other factors such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and pressure. The point at which a solvent cannot hold any more solute is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1784\">saturation<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">Precipitation<\/a> can occur when the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a> falls, when the solute evaporates, or with changing chemical conditions in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a>. An example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> in our homes is when water evaporates and leaves behind a rind of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> on faucets, shower heads, and drinking glasses.<\/p>\n<p>In nature, changes in environmental conditions may cause the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> dissolved in water to form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> and grow into crystals or cement grains of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediment<\/a> together. In Utah, deposits of tufa formed from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>-rich springs that emerged into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_747\">ice age<\/a> Lake Bonneville. Now exposed in dry valleys, this porous tufa was a natural insulation used by pioneers to build their homes with a natural protection against summer heat and winter cold. The travertine terraces at Mammoth Hot Springs in Yellowstone Park are another example formed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> at the edges of the shallow spring-fed ponds.<\/p>\n<figure id=\"attachment_2762\" aria-describedby=\"caption-attachment-2762\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.6_1200px-Bonneville_Salt_Flats.jpg\"><img class=\"size-medium wp-image-2762\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.6_1200px-Bonneville_Salt_Flats-300x197-1.jpg\" alt=\"The Bonneville Salt Flats of Utah\" width=\"300\" height=\"197\"><\/a><figcaption id=\"caption-attachment-2762\" class=\"wp-caption-text\">The Bonneville Salt Flats of Utah<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Another example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> occurs in the Great Salt Lake, Utah, where the concentration of sodium chloride and other salts is nearly eight times greater than in the world\u2019s oceans <\/span><span style=\"font-weight: 400\">[zotpressInText item=\"{DU5CMSHJ}\" format=\"%num%\" brackets=\"yes\"]<\/span><span style=\"font-weight: 400\">.\u00a0<\/span>Streams carry salt ions into the lake from the surrounding mountains. With no other outlet, the water in the lake evaporates and the concentration of salt increases until <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1784\">saturation<\/a> is reached and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitate<\/a> out as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a>. Similar salt deposits include halite and other precipitates, and occur in other lakes like Mono Lake in California and the Dead Sea.<\/p>\n<h3><b>3.2.2 Crystallization from Magma<\/b><\/h3>\n<figure id=\"attachment_2763\" aria-describedby=\"caption-attachment-2763\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5a_Pahoehoe_toe.jpg\"><img class=\"size-medium wp-image-2763\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.5a_Pahoehoe_toe-300x188-1.jpg\" alt=\"A lava flow\" width=\"300\" height=\"188\"><\/a><figcaption id=\"caption-attachment-2763\" class=\"wp-caption-text\">Lava, magma at the earth\u2019s surface<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Heat is energy that causes atoms in substances to vibrate. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">Temperature<\/a> is a measure of the intensity of the vibration. If the vibrations are violent enough, chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> are broken and the crystals melt releasing the ions into the melt. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">Magma<\/a> is molten rock with freely moving ions. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> is emplaced at depth or extruded onto the surface (then called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1751\">lava<\/a>), it starts to cool and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals can form.<\/p>\n<h3><b>3.2.3 Precipitation by Organisms<\/b><\/h3>\n<figure id=\"attachment_2764\" aria-describedby=\"caption-attachment-2764\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.8_Ammonite_Asteroceras.jpg\"><img class=\"size-full wp-image-2764\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.8_Ammonite_Asteroceras.jpg\" alt=\"Shell of an ammonite, an extinct cephalopod, with a spiral shell in a plane.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2764\" class=\"wp-caption-text\">Ammonite shell made of calcium carbonate<\/figcaption><\/figure>\n<p><span style=\"font-size: 1em\">Many organisms build bones, shells, and body coverings by extracting ions from water and precipitating <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> biologically. The most common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitated<\/a> by organisms is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, or calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> (CaCO3). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a> is often <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitated<\/a> by organisms as a polymorph called aragonite. <\/span><strong style=\"font-size: 1em\">Polymorphs<\/strong><span style=\"font-size: 1em\"> are crystals with the same chemical formula but different crystal structures. Marine invertebrates such as corals and clams <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitate<\/a> aragonite or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> for their shells and structures. Upon death, their hard parts accumulate on the ocean floor as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a>, and eventually may become the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a> limestone. Though limestone can form inorganically, the vast majority is formed by this biological process. Another example is marine organisms called radiolaria, which are zooplankton that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitate<\/a> silica for their microscopic external shells. When the organisms die, the shells accumulate on the ocean floor and can form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a> chert. An example of biologic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1274\">vertebrate<\/a> world is bone, which is composed mostly of a type of apatite, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">phosphate<\/a> group. The apatite found in bones contains calcium and water in its structure and is called hydroxycarbonate apatite, Ca<\/span><sub>5<\/sub><span style=\"font-size: 1em\">(PO<\/span><sub>4<\/sub><span style=\"font-size: 1em\">)<\/span><sub>3<\/sub><span style=\"font-size: 1em\">(OH).\u00a0 As mentioned above, such substances are not technically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> until the organism dies and these hard parts become <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a>.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-19\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-19\" class=\"h5p-iframe\" data-content-id=\"19\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3753\" aria-describedby=\"caption-attachment-3753\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-154\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3753\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.3 Silicate Minerals<\/span><\/h2>\n<figure id=\"attachment_2765\" aria-describedby=\"caption-attachment-2765\" style=\"width: 256px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedron.gif\"><img class=\"size-full wp-image-2765\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tetrahedron.gif\" alt=\"It is a pyramid shape with a triangular base\" width=\"256\" height=\"256\"><\/a><figcaption id=\"caption-attachment-2765\" class=\"wp-caption-text\">Rotating animation of a tetrahedra<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> are categorized based on their composition and structure. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">Silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are built around a molecular ion called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedron<\/a><\/strong>. A tetrahedron has a pyramid-like shape with four sides and four corners.\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">Silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> form the largest group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> on Earth, comprising the vast majority of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. Of the nearly four thousand known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> on Earth, most are rare. There are only a few that make up most of the rocks likely to be encountered by surface dwelling creatures like us. These are generally called the <strong>rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a><\/strong>.<\/p>\n<figure id=\"attachment_2766\" aria-describedby=\"caption-attachment-2766\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.10_Tetrahedron.jpg\"><img class=\"size-medium wp-image-2766\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.10_Tetrahedron-300x300-1.jpg\" alt=\"Model of silicon-oxygen tetrahedron of ping pong balls with a tiny silicon ion in the space in the middle of the four large balls\" width=\"300\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2766\" class=\"wp-caption-text\">Ping pong ball model of tetrahedron: balls are oxygen, lead sinker in center is silicon<\/figcaption><\/figure>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedron<\/a> (SiO<sub>4<\/sub>) consists of a single silicon atom at the center and four oxygen atoms located at the four corners of the tetrahedron. Each oxygen ion has a -2 charge and the silicon ion has a +4 charge. The silicon ion shares one of its four valence electrons with each of the four oxygen ions in a covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> to create a symmetrical geometric four-sided pyramid figure. Only half of the oxygen\u2019s valence electrons are shared, giving the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedron<\/a> an ionic charge of -4. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedron<\/a> forms bonds with many other combinations of ions to form the large group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2767\" aria-describedby=\"caption-attachment-2767\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.11_Tetrahedron_open.jpg\"><img class=\"size-medium wp-image-2767\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.11_Tetrahedron_open-300x255-1.jpg\" alt=\"Top ball removed showing the tiny silicon ion in the center\" width=\"300\" height=\"255\"><\/a><figcaption id=\"caption-attachment-2767\" class=\"wp-caption-text\">The silicon ion in the center of the tetrahedron<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The silicon ion is much smaller than the oxygen ions (see the figures) and fits into a small space in the center of the four large oxygen ions, seen if the top ball is removed (as shown in the figure to the right). <\/span><span style=\"font-weight: 400\">Because only one of the valence electrons of the corner oxygens is shared, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedron<\/a> has chemically active corners available to form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica tetrahedra<\/a> or other positively charged ions such as Al<\/span><sub><span style=\"font-weight: 400\">+3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">+2,+3<\/span><\/sub><span style=\"font-weight: 400\">, Mg<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">, K<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, Na<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, and Ca<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">. Depending on many factors, such as the original <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> chemistry, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica-oxygen tetrahedra<\/a> can combine with other tetrahedra in several different configurations. For example, tetrahedra can be isolated, attached in chains, sheets, or three dimensional structures. These combinations and others create the chemical structure in which positively charged ions can be inserted for unique chemical compositions forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> groups. \u00a0\u00a0<\/span><\/p>\n<h3><b>3.3.1 The dark ferromagnesian silicates<\/b><\/h3>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2768\" aria-describedby=\"caption-attachment-2768\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.12_Peridot_in_basalt.jpg\"><img class=\"size-medium wp-image-2768\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.12_Peridot_in_basalt-300x225-1.jpg\" alt=\"Many small crystall of the green mineral olivine in a mass of basalt\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2768\" class=\"wp-caption-text\">Olivine crystals in basalt<\/figcaption><\/figure>\n<p><span style=\"font-size: 14pt\"><b>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">Olivine<\/a> Family<\/b><\/span><\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">Olivine<\/a> is the primary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> component in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> rock such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1666\">peridotite<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>. It is characteristically green when not weathered. The chemical formula is (Fe,Mg)<sub>2<\/sub>SiO<sub>4<\/sub>. As previously described, the comma between iron (Fe) and magnesium (Mg) indicates these two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> occur in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a>.\u00a0<span style=\"font-weight: 400\">Not to be confused with a liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> occurs when two or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> have similar properties and can freely substitute for each other in the same location in the crystal structure.<\/span><\/p>\n<figure id=\"attachment_2769\" aria-describedby=\"caption-attachment-2769\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.13_Atomic_structure_of_olivine_1.png\"><img class=\"size-full wp-image-2769\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.13_Atomic_structure_of_olivine_1.png\" alt=\"Tetrahedral structure of olivine showing the independent tetrahedra connected together by anions of iron and\/or magnesium.\" width=\"300\" height=\"258\"><\/a><figcaption id=\"caption-attachment-2769\" class=\"wp-caption-text\">Tetrahedral structure of olivine<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">Olivine<\/a> is referred to as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> family because of the ability of iron and magnesium to substitute for each other. Iron and magnesium in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> family indicates a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> forming a compositional series within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> group which can form crystals of all iron as one end member and all mixtures of iron and magnesium in between to all magnesium at the other end member. Different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> names are applied to compositions between these end members.\u00a0 In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, the iron and magnesium ions in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> are about the same size and charge, so either atom can fit into the same location in the growing crystals. Within the cooling <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals continue to grow until they solidify into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous rock<\/a>. The relative amounts of iron and magnesium in the parent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> determine which <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in the series form. Other rarer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> with similar properties to iron or magnesium, like manganese (Mn), can substitute into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> crystalline structure in small amounts. Such ionic substitutions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals give rise to the great variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and are often responsible for differences in color and other properties within a group or family of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">Olivine<\/a> has a pure iron end-member (called fayalite) and a pure magnesium end-member (called forsterite). Chemically, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> is mostly silica, iron, and magnesium and therefore is grouped among the dark-colored <\/span>ferromagnesian<span style=\"font-weight: 400\"> (iron=ferro, magnesium=magnesian) or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a><\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, a contraction of their chemical symbols Ma and Fe. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">Mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are also referred to as dark-colored ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. <em>Ferro<\/em> means iron and <em>magnesian<\/em> refers to magnesium. Ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> tend to be more dense than non-ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a>. This difference in density ends up being important in controlling the behavior of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> rocks that are built from these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>: whether a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducts<\/a> or not is largely governed by the density of its rocks, which are in turn controlled by the density of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that comprise them.<\/span><\/p>\n<p>The crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> is built from independent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica tetrahedra<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals <\/a>with independent tetrahedral structures are called neosilicates (or orthosilicates). In addition to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a>, other common neosilicate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> include garnet, topaz, kyanite, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1227\">zircon<\/a>.<\/p>\n<p>Two other similar arrangements of tetrahedra are close in structure to the neosilicates and grade toward the next group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, the pyroxenes. In a variation on independent tetrahedra called sorosilicates, there are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that share one oxygen between two tetrahedra, and include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> like pistachio-green epidote, a gemstone. Another variation are the cyclosilicates, which as the name suggests, consist of tetrahedral rings, and include gemstones such as beryl, emerald, aquamarine, and tourmaline<\/p>\n<h3><b>3.3.2 Pyroxene Family<\/b><\/h3>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2770\" aria-describedby=\"caption-attachment-2770\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img class=\"wp-image-2770 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"300\" height=\"231\"><\/a><figcaption id=\"caption-attachment-2770\" class=\"wp-caption-text\">Crystals of diopside, a member of the pyroxene family<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2771\" aria-describedby=\"caption-attachment-2771\" style=\"width: 70px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Pyroxen-chain.png\"><img class=\"wp-image-2771\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.15_Pyroxen-chain.png\" alt=\"Single chain of tetrahedra in pyroxene, alternating with adjacent corner oxygens bonded. The outer corners are active to bond with other anions.\" width=\"70\" height=\"517\"><\/a><figcaption id=\"caption-attachment-2771\" class=\"wp-caption-text\">Single chain tetrahedral structure in pyroxene<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">Pyroxene<\/a> is another family of dark ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, typically black or dark green in color. Members of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a> family have a complex chemical composition that includes iron, magnesium, aluminum, and other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> to polymerized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica tetrahedra<\/a>. <strong>Polymers<\/strong> are chains, sheets, or three-dimensional structures, and are formed by multiple tetrahedra covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> via their corner oxygen atoms. Pyroxenes are commonly found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> rocks such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1666\">peridotite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1016\">gabbro<\/a>, as well as metamorphic rocks like eclogite and blue schist.<\/p>\n<p>Pyroxenes are built from long, single chains of polymerized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica tetrahedra<\/a> in which tetrahedra share two corner oxygens. The silica chains are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> together into the crystal structures by metal cations. A common member of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a> family is augite, itself containing several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> series with a complex chemical formula (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)<sub>2<\/sub>O<sub>6<\/sub> that gives rise to a number of individual <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> names.<\/p>\n<p>This single-chain crystalline structure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> with many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>, which can also freely substitute for each other. The generalized chemical composition for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a> is XZ(Al,Si)<sub>2<\/sub>O<sub>6<\/sub>. X represents the ions Na, Ca, Mg, or Fe, and Z represents Mg, Fe, or Al. These ions have similar ionic sizes, which allows many possible substitutions among them. Although the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cations<\/a> may freely substitute for each other in the crystal, they carry different ionic charges that must be balanced out in the final crystalline structure. For example Na has a charge of +1, but Ca has charge of +2. If a Na<sup>+<\/sup> ion substitutes for a Ca<sup>+2<\/sup> ion, it creates an unequal charge that must be balanced by other ionic substitutions elsewhere in the crystal. Note that ionic size is more important than ionic charge for substitutions to occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> series in crystals.<\/p>\n<h3><\/h3>\n<h3><b>3.3.3 Amphibole Family<\/b><\/h3>\n<figure id=\"attachment_2773\" aria-describedby=\"caption-attachment-2773\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Orthoclase_Hornblende.jpg\"><img class=\"wp-image-2773\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.15_Orthoclase_Hornblende-300x300-1.jpg\" alt=\"A crystal of orthoclase (potassium feldspar) wth elongated dark crystals of hornblende\" width=\"200\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2773\" class=\"wp-caption-text\">Elongated crystals of hornblende in orthoclase<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2772\" aria-describedby=\"caption-attachment-2772\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.16_Amphibole.jpg\"><img class=\"wp-image-2772\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.16_Amphibole-300x236-1.jpg\" alt=\"Black crystals of hornblende\" width=\"200\" height=\"157\"><\/a><figcaption id=\"caption-attachment-2772\" class=\"wp-caption-text\">Hornblende crystals<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">Amphibole<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are built from polymerized double silica chains and they are also referred to as inosilicates. Imagine two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a> chains that connect together by sharing a third oxygen on each tetrahedra.\u00a0 Amphiboles are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> and metamorphic rocks and typically have a long-bladed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a><\/strong>. The most common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a>, hornblende, is usually black; however, they come in a variety of colors depending on their chemical composition. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a>, amphibolite, is primarily composed of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2774\" aria-describedby=\"caption-attachment-2774\" style=\"width: 79px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.17_Tremolite-chain.png\"><img class=\"size-medium wp-image-2774\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.17_Tremolite-chain-79x300-1.png\" alt=\"Double chain structure of amphibole; two single chains laying together with the inner corners of each tetrahedron bonded and the outer cornera active to bond with anions\" width=\"79\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2774\" class=\"wp-caption-text\">Double chain structure<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Amphiboles are composed of iron, magnesium, aluminum, and other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cations<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica tetrahedra<\/a>. These dark ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are commonly found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1016\">gabbro<\/a>, baslt, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1015\">diorite<\/a>, and often form the black specks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a>. Their chemical formula is very complex and generally written as (RSi<sub>4<\/sub>O<sub>11<\/sub>)<sub>2<\/sub>, where R represents many different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cations<\/a>. For example, it can also be written more exactly as AX<sub>2<\/sub>Z<sub>5<\/sub>((Si,Al,Ti)<sub>8<\/sub>O<sub>22<\/sub>)(OH,F,Cl,O)<sub>2<\/sub>. In this formula A may be Ca, Na, K, Pb, or blank; X equals Li, Na, Mg, Fe, Mn, or Ca; and Z is Li, Na, Mg, Fe, Mn, Zn, Co, Ni, Al, \u00a0Cr, Mn, V, Ti, or Zr. The substitutions create a wide variety of colors such as green, black, colorless, white, yellow, blue, or brown. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">Amphibole<\/a> crystals can also include hydroxide ions (OH<sup>-<\/sup>)<sup>,<\/sup> which occurs from an interaction between the growing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and water dissolved in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>.<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3><strong>3.3.4 Sheet Silicates<\/strong><\/h3>\n<figure id=\"attachment_2775\" aria-describedby=\"caption-attachment-2775\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany.jpg\"><img class=\"wp-image-2775\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany-300x225-1.jpg\" alt=\"Dark brown crystals of biotite mica showing sheet-like habit\" width=\"200\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2775\" class=\"wp-caption-text\">Sheet crystals of biotite mica<\/figcaption><\/figure>\n<figure id=\"attachment_3637\" aria-describedby=\"caption-attachment-3637\" style=\"width: 250px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MicaSheetUSGOV.jpg\"><img class=\"wp-image-166\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MicaSheetUSGOV-300x226.jpg\" alt=\"Crystal of muscovite mica showing sheet structure of the mineral\" width=\"250\" height=\"188\"><\/a><figcaption id=\"caption-attachment-3637\" class=\"wp-caption-text\">Crystal of muscovite mica<\/figcaption><\/figure>\n<p>Sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> are built from tetrahedra which share all three of their bottom corner oxygens thus forming sheets of tetrahedra with their top corners available for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonding<\/a> with other atoms. Micas and clays are common types of sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a>, also known as phyllosilicates. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">Mica<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> and metamorphic rocks, while clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are more often found in sedimentary rocks. Two frequently found micas are dark-colored <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">biotite<\/a>, frequently found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a>, and light-colored <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">muscovite<\/a>, found in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1762\">metamorphic rock<\/a> called schist.<\/p>\n<figure id=\"attachment_2777\" aria-describedby=\"caption-attachment-2777\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.20_Silicate-sheet-3D-polyhedra.png\"><img class=\"size-medium wp-image-2777\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.20_Silicate-sheet-3D-polyhedra-300x197-1.png\" alt=\"Continuous sheets of tetradedra with all three base corners bonded to each other; the top corner active to bond with anions\" width=\"300\" height=\"197\"><\/a><figcaption id=\"caption-attachment-2777\" class=\"wp-caption-text\">Sheet structure of mica<\/figcaption><\/figure>\n<p>Chemically, sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> usually contain silicon and oxygen in a 2:5 ratio (Si<sub>4<\/sub>O<sub>10<\/sub>). Micas contain mostly silica, aluminum, and potassium. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">Biotite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> has more iron and magnesium and is considered a ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">Muscovite<\/a> micas belong to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">Felsic<\/a> is a contraction formed from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, the dominant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> rocks.<\/p>\n<figure id=\"attachment_2778\" aria-describedby=\"caption-attachment-2778\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.21_Crystal-structure-of-mica.jpg\"><img class=\"size-medium wp-image-2778\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.21_Crystal-structure-of-mica-300x300-1.jpg\" alt=\"Diagram of mica crystal structure with the sheets of tetrahedra inverted onto each other into sandwiches with the active corners bonded with anions and the sandwiches connected together with large potassium ions that form weak bonds easily separated so the crystal comes apart into sheets.\" width=\"300\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2778\" class=\"wp-caption-text\">Crystal structure of a mica<\/figcaption><\/figure>\n<figure id=\"attachment_2779\" aria-describedby=\"caption-attachment-2779\" style=\"width: 296px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Illmenite-mica-sandwich.jpg\"><img class=\"size-medium wp-image-2779\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Illmenite-mica-sandwich-296x300-1.jpg\" alt=\"Silica sheets layered in mica like bread and hjam in a stack of sandwiches\" width=\"296\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2779\" class=\"wp-caption-text\">Mica \"silica sandwich\" structure<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>The illustration of the crystalline structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> shows the corner O atoms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> with K, Al, Mg, Fe, and Si atoms, forming polymerized sheets of linked tetrahedra, with an octahedral layer of Fe, Mg, or Al, between them.\u00a0 The yellow potassium ions form Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> (attraction and repulsion between atoms, molecules, and surfaces) and hold the sheets together. Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> differ from\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Covalent_bond\">covalent<\/a>\u00a0and\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Ionic_bond\">ionic<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a>, and exist here between the sandwiches, holding them together into a stack of sandwiches. The Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> are weak compared to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> within the sheets, allowing the sandwiches to be separated along the potassium layers. This gives <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a> its characteristic property of easily cleaving into sheets.<\/p>\n<figure id=\"attachment_2780\" aria-describedby=\"caption-attachment-2780\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.22_Kaolinite-structure.jpg\"><img class=\"size-medium wp-image-2780\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.22_Kaolinite-structure-300x244-1.jpg\" alt=\"Crystal structure of kaolinite, a clay mineral with sheet structure like mica except that the\" width=\"300\" height=\"244\"><\/a><figcaption id=\"caption-attachment-2780\" class=\"wp-caption-text\">Structure of kaolinite<\/figcaption><\/figure>\n<p>Clays <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a> formed by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a> of rocks and are another family of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> with a tetrahedral sheet structure. Clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> form a complex family, and are an important component of many sedimentary rocks. Other sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> include serpentine and chlorite, found in metamorphic rocks.<\/p>\n<p>Clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are composed of hydrous aluminum <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a>. One type of clay, kaolinite, has a structure like an open-faced sandwich, with the bread being a single layer of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedra<\/a> and a layer of aluminum as the spread in an octahedral configuration with the top oxygens of the sheets.<\/p>\n<h3><b>3.3.5 Framework Silicates<\/b><\/h3>\n<figure id=\"attachment_2829\" aria-describedby=\"caption-attachment-2829\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img class=\"size-medium wp-image-2829\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2829\" class=\"wp-caption-text\">Freely growing quartz crystals showing crystal faces<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">Quartz<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> are the two most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a>. In fact, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> itself is the single most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. There are two types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, one containing potassium and abundant in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> rocks of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a>, and the other with sodium and calcium abundant in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a> rocks of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic crust<\/a>.\u00a0 Together with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are classified as framework <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a>. They are built with a three-dimensional framework of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica tetrahedra<\/a> in which all four corner oxygens are shared with adjacent tetrahedra. Within these frameworks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> are holes and spaces into which other ions like aluminum, potassium, sodium, and calcium can fit giving rise to a variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> compositions and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> names.<\/p>\n<figure id=\"attachment_2781\" aria-describedby=\"caption-attachment-2781\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/min-crust-pie-chart.jpg\"><img class=\"size-medium wp-image-2781\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/min-crust-pie-chart-300x290-1.jpg\" alt=\"Feldspar is 51% of the chart.\" width=\"300\" height=\"290\"><\/a><figcaption id=\"caption-attachment-2781\" class=\"wp-caption-text\">Mineral abundance pie chart in Earth's crust by Callan Bentley.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">Feldspars<\/a> are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1010\">rhyolite<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a> as well as metamorphic rocks and detrital sedimentary rocks. Detrital sedimentary rocks are composed of mechanically weathered rock particles, like sand and gravel. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">Quartz<\/a> is especially abundant in detrital sedimentary rocks because it is very resistant to disintegration by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>. While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> is the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> on the Earth's surface, due to its durability, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in the Earth's <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>, comprising roughly 50% of the total <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that make up the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>.<\/p>\n<figure id=\"attachment_2782\" aria-describedby=\"caption-attachment-2782\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.24_kspar280x210-1.jpg\"><img class=\"size-medium wp-image-2782\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.24_kspar280x210-1-300x200-1.jpg\" alt=\"A group of crystals of pink potassium feldspar\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2782\" class=\"wp-caption-text\">Pink orthoclase crystals<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">Quartz<\/a> is composed of pure silica, SiO<sub>2<\/sub>, with the tetrahedra arranged in a three dimensional framework. Impurities consisting of atoms within this framework give rise to many varieties of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> among which are gemstones like amethyst, rose <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, and citrine.\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">Feldspars<\/a> are mostly silica with aluminum, potassium, sodium, and calcium. Orthoclase <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> (KAlSi<sub>3<\/sub>O<sub>8<\/sub>), also called potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">K-spar<\/a>, is made of silica, aluminum, and potassium. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">Quartz<\/a> and orthoclase <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1006\">Felsic<\/a> is the compositional term applied to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and rocks that contain an abundance of silica. Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> with the formula (Ca,Na)AlSi<sub>3<\/sub>O<sub>8<\/sub>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> (Ca,Na) indicating a series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, one end of the series with calcium CaAl<sub>2<\/sub>Si<sub>2<\/sub>O<sub>8<\/sub>, called anorthite, and the other end with sodium NaAlSi<sub>3<\/sub>O<sub>8<\/sub>, called albite.\u00a0Note how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> accommodates the substitution of Ca<sup>++<\/sup> and Na<sup>+<\/sup>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> in this solid solution series have different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> names.<\/p>\n<figure id=\"attachment_2783\" aria-describedby=\"caption-attachment-2783\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/23-feldspar-structure.gif\"><img class=\"size-medium wp-image-2783\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/23-feldspar-structure-300x271-1.gif\" alt=\"Framework structure of feldspar with all corners of tetrahedra shared with adjacent tetrahedra; there are holes in the structure in which large anions like potassium and sodium\/calcium fit\" width=\"300\" height=\"271\"><\/a><figcaption id=\"caption-attachment-2783\" class=\"wp-caption-text\">Crystal structure of feldspar<\/figcaption><\/figure>\n<p>Note that aluminum, which has a similar ionic size to silicon, can substitute for silicon inside the tetrahedra (see figure). Because potassium ions are so much larger than sodium and calcium ions, which are very similar in size, the inability of the crystal lattice to accommodate both potassium and sodium\/calcium gives rise to the two families of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, orthoclase and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> respectively.\u00a0Framework <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> are called tectosilicates and include the alkali metal-rich feldspathoids and zeolites.<\/p>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-20\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-20\" class=\"h5p-iframe\" data-content-id=\"20\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3752\" aria-describedby=\"caption-attachment-3752\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-175\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3752\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.3 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.4 Non-Silicate Minerals<\/span><\/h2>\n<figure id=\"attachment_2784\" aria-describedby=\"caption-attachment-2784\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite.jpg\"><img class=\"size-medium wp-image-2784\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hanksite-300x200-1.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2784\" class=\"wp-caption-text\">Hanksite, Na22K(SO4)9(CO3)2Cl, one of the few minerals that is considered a carbonate and a sulfate<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The crystal structure of non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> (see table) does not contain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silica-oxygen tetrahedra<\/a>. Many non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are economically important and provide metallic resources such as copper, lead, and iron. They also include valuable non-metallic products such as salt, construction materials, and fertilizer.<\/p>\n<table>\n<tbody>\n<tr>\n<td><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a> \u00a0Group<\/b><\/td>\n<td><b>Examples<\/b><\/td>\n<td><b>Formula<\/b><\/td>\n<td><b>Uses<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">Native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">gold, silver, copper<\/span><\/td>\n<td><span style=\"font-weight: 400\">Au, Ag, Cu<\/span><\/td>\n<td><span style=\"font-weight: 400\">Jewelry, coins, industry<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">Carbonates<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, dolomite <\/span><\/td>\n<td><span style=\"font-weight: 400\">CaCO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, CaMg(CO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><\/td>\n<td><span style=\"font-weight: 400\">Lime, Portland cement<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">Oxides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">hematite, magnetite, bauxite<\/span><\/td>\n<td><span style=\"font-weight: 400\">Fe<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">, a mixture of aluminum <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">Ores of iron &amp; aluminum, pigments <\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_972\">Halides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">halite, sylvite<\/span><\/td>\n<td><span style=\"font-weight: 400\">NaCl, KCl<\/span><\/td>\n<td><span style=\"font-weight: 400\">Table salt, fertilizer<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">Sulfides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">galena, chalcopyrite, cinnabar<\/span><\/td>\n<td><span style=\"font-weight: 400\">PbS, CuFeS<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">, HgS<\/span><\/td>\n<td><span style=\"font-weight: 400\">Ores of lead, copper, mercury<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">Sulphates<\/span><\/td>\n<td><span style=\"font-weight: 400\">gypsum, epsom salts<\/span><\/td>\n<td><span style=\"font-weight: 400\">CaSo<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b72H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O, MgSO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b77H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><\/td>\n<td><span style=\"font-weight: 400\">Sheetrock, therapeutic soak<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">Phosphates<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">apatite<\/span><\/td>\n<td><span style=\"font-weight: 400\">Ca<\/span><sub><span style=\"font-weight: 400\">5<\/span><\/sub><span style=\"font-weight: 400\">(PO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">(F,Cl,OH) <\/span><\/td>\n<td><span style=\"font-weight: 400\">Fertilizer, teeth, bones<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em><span style=\"font-weight: 400\">Common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\"><em>silicate<\/em><\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\"><em>mineral<\/em><\/a> groups.<\/span><\/em><\/p>\n<h3><b>3.4.1 Carbonates<\/b><\/h3>\n<figure id=\"attachment_2785\" aria-describedby=\"caption-attachment-2785\" style=\"width: 245px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img class=\"size-medium wp-image-2785\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"245\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2785\" class=\"wp-caption-text\">Calcite crystal in shape of rhomb. Note the double-refracted word \u201ccalcite\u201d in the center of the figure due to birefringence.<\/figcaption><\/figure>\n<figure id=\"attachment_2786\" aria-describedby=\"caption-attachment-2786\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.29_Limestone_etched_section_KopeFm_new.jpg\"><img class=\"wp-image-2786\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.29_Limestone_etched_section_KopeFm_new-281x300-1.jpg\" alt=\"Piece of limestone rock full of small fossils\" width=\"200\" height=\"214\"><\/a><figcaption id=\"caption-attachment-2786\" class=\"wp-caption-text\">Limestone with small fossils<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a>\u00a0(CaCO<sub>3<\/sub>) and dolomite (CaMg(CO<sub>3<\/sub>)<sub>2<\/sub>) are the two most frequently occurring <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, and usually occur in sedimentary rocks, such as limestone and dolostone rocks, respectively. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> rocks, such <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> and dolomite, are formed via evaporation and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitation<\/a>. However, most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a>-rich rocks, such as limestone, are created by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1760\">lithification<\/a> of fossilized marine organisms. These organisms, including those we can see and many microscopic organisms, have shells or exoskeletons consisting of calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> (CaCO<sub>3<\/sub>). When these organisms die, their remains accumulate on the floor of the water body in which they live and the soft body parts decompose and dissolve away. The calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> hard parts become included in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a>, eventually becoming the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1761\">sedimentary rock<\/a> called limestone. While limestone may contain large, easy to see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a>, most limestones contain the remains of microscopic creatures and thus originate from biological processes.<\/p>\n<figure id=\"attachment_2787\" aria-describedby=\"caption-attachment-2787\" style=\"width: 282px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Bifringence.jpg\"><img class=\"size-medium wp-image-2787\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bifringence-282x300-1.jpg\" alt=\"Calcite crystal polarize light into two waves that vibrate at right angles to each other and pass through the crystal in different paths.\" width=\"282\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2787\" class=\"wp-caption-text\">Bifringence in calcite crystals<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a> crystals show an interesting property called <strong>birefringence<\/strong>, meaning they polarize light into two wave components vibrating at right angles to each other. As the two light waves pass through the crystal, they travel at different velocities and are separated by refraction into two different travel paths. In other words, the crystal produces a double image of objects viewed through it. Because they polarize light, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> crystals are used in special petrographic microscopes for studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and rocks.<\/p>\n<p>Many non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are referred to as salts. The term <strong>salts<\/strong> used here refers to compounds made by replacing the hydrogen in natural acids. The most abundant natural acid is carbonic acid that forms by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a> of carbon dioxide in water. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">Carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are salts built around the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> ion (CO3<sup>-2<\/sup>) where calcium and\/or magnesium replace the hydrogen in carbonic acid (H<sub>2<\/sub>CO<sub>3<\/sub>). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a> and a closely related polymorph aragonite are secreted by organisms to form shells and physical structures like corals. Many such creatures draw both calcium and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> from dissolved bicarbonate ions (HCO<sub>3<\/sub><sup>-<\/sup>) in ocean water. As seen in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> identification section below, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> is easily dissolved in acid and thus effervesces in dilute hydrochloric acid (HCl). Small dropper bottles of dilute hydrochloric acid are often carried by geologists in the field as well as used in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> identification labs.<\/p>\n<p>Other salts include halite (NaCl) in which sodium replaces the hydrogen in hydrochloric acid and gypsum (Ca[SO<sub>4<\/sub>] \u2022 2 H<sub>2<\/sub>O) in which calcium replaces the hydrogen in sulfuric acid. Note that some water molecules are also included in the gypsum crystal. Salts are often formed by evaporation and are called evaporite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2788\" aria-describedby=\"caption-attachment-2788\" style=\"width: 425px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.30_Crystal_structure_of_Calcite.png\"><img class=\"wp-image-2788\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.30_Crystal_structure_of_Calcite.png\" alt=\"Crystal structure of calcite showing the carbonate units of carbon surrounded by three oxygen ions and bonded to calcium ions.\" width=\"425\" height=\"520\"><\/a><figcaption id=\"caption-attachment-2788\" class=\"wp-caption-text\">Crystal structure of calcite<\/figcaption><\/figure>\n<p>The figure shows the crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> (CaCO<sub>3<\/sub>). Like silicon, carbon has four valence electrons. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> unit consists of carbon atoms (tiny white dots) covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> to three oxygen atoms (red), one oxygen sharing two valence electrons with the carbon and the other two sharing one valence electron each with the carbon, thus creating triangular units with a charge of -2. The negatively charged <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> unit forms an ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> with the Ca ion (blue), which as a charge of +2.<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><b>3.4.2 Oxides, Halides, and Sulfides<\/b><\/h3>\n<figure id=\"attachment_2789\" aria-describedby=\"caption-attachment-2789\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img class=\"size-medium wp-image-2789\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"300\" height=\"256\"><\/a><figcaption id=\"caption-attachment-2789\" class=\"wp-caption-text\">Limonite, a hydrated oxide of iron<\/figcaption><\/figure>\n<p>After <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonates<\/a>, the next most common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_972\">halides<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfides<\/a>.<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">Oxides<\/a> consist of metal ions covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> with oxygen. The most familiar <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> is rust, which is a combination of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a> (Fe<sub>2<\/sub>O<sub>3<\/sub>) and hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a>. Hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a> form when iron is exposed to oxygen and water. Iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a> are important for producing metallic iron. When iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> or ore is smelted, it produces carbon dioxide (CO<sub>2<\/sub>) and metallic iron.<\/p>\n<p>The red color in rocks is usually due to the presence of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a>. For example, the red sandstone cliffs in Zion National Park and throughout Southern Utah consist of white or colorless grains of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> coated with iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> which serve as cementing agents holding the grains together.<\/p>\n<figure id=\"attachment_2790\" aria-describedby=\"caption-attachment-2790\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503.jpg\"><img class=\"wp-image-2790 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503-300x269-1.jpg\" alt=\"A red form of hematite called oolitic showing a mass of small round nodules\" width=\"300\" height=\"269\"><\/a><figcaption id=\"caption-attachment-2790\" class=\"wp-caption-text\">Oolitic hematite<\/figcaption><\/figure>\n<p>Other iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a> include limonite, magnetite, and hematite. Hematite occurs in many different crystal forms. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a> form shows no external structure. Botryoidal hematite shows large concentric blobs. Specular hematite looks like a mass of shiny metallic crystals. Oolitic hematite looks like a mass of dull red fish eggs. These different forms of hematite are polymorphs and all have the same formula, Fe<sub>2<\/sub>O<sub>3<\/sub>.<\/p>\n<p>Other common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> include:<\/p>\n<ul>\n<li>ice (H<sub>2<\/sub>O), an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> of hydrogen<\/li>\n<li>bauxite (Al<sub>2<\/sub>H<sub>2<\/sub>O<sub>4<\/sub>), hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a> of aluminum, an ore for producing metallic aluminum<\/li>\n<li>corundum (Al<sub>2<\/sub>O<sub>3<\/sub>), which includes ruby and sapphire gemstones.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2791\" aria-describedby=\"caption-attachment-2791\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.34_Halite-249324-1.jpg\"><img class=\"size-medium wp-image-2791\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.34_Halite-249324-1-300x225-1.jpg\" alt=\"Crystals of halite showing cubic crystal habit\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2791\" class=\"wp-caption-text\">Halite crystal showing cubic habit<\/figcaption><\/figure>\n<p>The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_972\">halides<\/a><\/strong> consist of halogens in column VII, usually fluorine or chlorine, ionically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> with sodium or other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cations<\/a>. These include halite or sodium chloride (NaCl), common table salt; sylvite or potassium chloride (KCl); and fluorite or calcium fluoride (CaF<sub>2<\/sub>).<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2792\" aria-describedby=\"caption-attachment-2792\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level.jpg\"><img class=\"size-medium wp-image-2792\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level-300x220-1.jpg\" alt=\"Photo of salt crust at the Bonneville Salt Flats in Utah with mountains in the background.\" width=\"300\" height=\"220\"><\/a><figcaption id=\"caption-attachment-2792\" class=\"wp-caption-text\">Salt crystals at the Bonneville Salt Flats<\/figcaption><\/figure>\n<figure id=\"attachment_2793\" aria-describedby=\"caption-attachment-2793\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img class=\"size-medium wp-image-2793\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2793\" class=\"wp-caption-text\">Fluorite. B shows fluorescence of fluorite under UV light<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_972\">Halide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> usually form from the evaporation of sea water or other isolated bodies of water. A well-known example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_972\">halide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> deposits created by evaporation is the Bonneville Salt Flats, located west of the Great Salt Lake in Utah (see figure).<\/p>\n<p>&nbsp;<\/p>\n<p>Many important metal ores are <b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfides<\/a>, <\/b><span style=\"font-weight: 400\">in which metals are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> to sulfur.\u00a0<\/span><span style=\"font-weight: 400\">Significant examples include: \u00a0<\/span>galena<span style=\"font-weight: 400\"> (lead <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>), <\/span>sphalerite<span style=\"font-weight: 400\"> (zinc <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>),<\/span> pyrite<\/p>\n<figure id=\"attachment_2794\" aria-describedby=\"caption-attachment-2794\" style=\"width: 175px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.37_pyrite1.jpg\"><img class=\"wp-image-2794\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.37_pyrite1-283x300-1.jpg\" alt=\"Cubic crystals of iron pyrite, called &quot;fools gold&quot;\" width=\"175\" height=\"185\"><\/a><figcaption id=\"caption-attachment-2794\" class=\"wp-caption-text\">Cubic crystals of pyrite<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">(<\/span><span style=\"font-weight: 400\">iron<\/span><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>, sometimes called \u201cfool's gold\u201d), and <\/span>chalcopyrite <span style=\"font-weight: 400\">(iron-copper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a>).<\/span><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">Sulfides<\/a> are well known for being important ore <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. For example, galena is the main source of lead, sphalerite is the main source of zinc, and chalcopyrite is the main copper ore <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> mined in porphyry deposits like the Bingham mine (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/16-energy-and-mineral-resources\/\">chapter 16<\/a>). The largest sources of nickel, antimony, molybdenum, arsenic, and mercury are also <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfides<\/a>.<\/span><\/p>\n<h3><b>3.4.3 Sulfates<\/b><\/h3>\n<figure id=\"attachment_2795\" aria-describedby=\"caption-attachment-2795\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.39_SeleniteGypsumUSGOV.jpg\"><img class=\"size-medium wp-image-2795\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.39_SeleniteGypsumUSGOV-300x284-1.jpg\" alt=\"A clear crystal of gypsum\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2795\" class=\"wp-caption-text\">Gypsum crystal<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">Sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> contain a metal ion, such as calcium, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonded<\/a> to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">sulfate<\/a> ion. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">sulfate<\/a> ion is a combination of sulfur and oxygen (SO<sub>4<sup>-<\/sup><\/sub><sup>2<\/sup>). The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> gypsum (CaSO<sub>4<\/sub>\u14272H<sub>2<\/sub>O) is used in construction materials such as plaster and drywall. Gypsum is often formed from evaporating water and usually contains water molecules in its crystalline structure. The \u14272H<sub>2<\/sub>O in the formula indicates the water molecules are whole H<sub>2<\/sub>O. This is different from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a>, which contain a hydroxide ion (OH<sup>-<\/sup>) that is derived from water, but is missing a hydrogen ion (H<sup>+<\/sup>). The calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_974\">sulfate<\/a> without water is a different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> than gypsum called anhydrite (CaSO<sub>4<\/sub>).<\/p>\n<h3><b>3.4.4 Phosphates<\/b><\/h3>\n<figure id=\"attachment_2796\" aria-describedby=\"caption-attachment-2796\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.40_Apatite_Canada.jpg\"><img class=\"wp-image-2796\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.40_Apatite_Canada-236x300-1.jpg\" alt=\"A crystal of apatite\" width=\"150\" height=\"191\"><\/a><figcaption id=\"caption-attachment-2796\" class=\"wp-caption-text\">Apatite crystal<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">Phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> have a tetrahedral <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">phosphate<\/a> unit (PO<sub>4<\/sub><sup>-3<\/sup>) combined with various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1782\">anions<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1780\">cations<\/a>. In some cases arsenic or vanadium can substitute for phosphorus. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">Phosphates<\/a> are an important ingredient of fertilizers as well as detergents, paint, and other products. The best known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> is apatite, Ca<sub>5<\/sub>(PO<sub>4<\/sub>)<sub>3<\/sub>(F,Cl,OH), variations of which are found in teeth and bones. The gemstone turquoise [CuAl<sub>6<\/sub>(PO<sub>4<\/sub>)<sub>4<\/sub>(OH)<sub>8<\/sub>\u00b74H2O ] is a copper-rich <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_975\">phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> that, like gypsum, contains water molecules.<\/span><\/p>\n<h3><b>3.4.5 Native Element Minerals<\/b><\/h3>\n<figure id=\"attachment_2798\" aria-describedby=\"caption-attachment-2798\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.43_Sulfer_Fumarola_Vulcano.jpg\"><img class=\"wp-image-2798\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.43_Sulfer_Fumarola_Vulcano-300x225-1.jpg\" alt=\"Native sulfur deposited around the vent of a volcanic fumarole\" width=\"200\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2798\" class=\"wp-caption-text\">Native sulfur deposited around a volcanic fumarole<\/figcaption><\/figure>\n<figure id=\"attachment_2797\" aria-describedby=\"caption-attachment-2797\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.41_Native_Copper-1.jpg\"><img class=\"wp-image-2797\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.41_Native_Copper-1-300x284-1.jpg\" alt=\"Metallic native copper\" width=\"200\" height=\"189\"><\/a><figcaption id=\"caption-attachment-2797\" class=\"wp-caption-text\">Native copper<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">Native element minerals<\/a>, usually metals, occur in nature in a pure or nearly pure state. Gold is an example of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>; it is not very reactive and rarely <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> so it is usually found in an isolated or pure state. The non-metallic and poorly-reactive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> carbon is often found as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a>, such as graphite and diamonds. Mildly reactive metals like silver, copper, platinum, mercury, and sulfur sometimes occur as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native element minerals<\/a>. Reactive metals such as iron, lead, and aluminum almost always <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> to other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> and are rarely found in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> state.<\/p>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-21\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-21\" class=\"h5p-iframe\" data-content-id=\"21\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.5 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3751\" aria-describedby=\"caption-attachment-3751\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.4-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-191\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3751\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.4 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.5 Identifying Minerals<\/span><\/h2>\n<figure id=\"attachment_2799\" aria-describedby=\"caption-attachment-2799\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Curiosity_Mars_Rover_Finds_Mineral_Match.jpg\"><img class=\"size-medium wp-image-2799\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Curiosity_Mars_Rover_Finds_Mineral_Match-300x268-1.jpg\" alt=\"The red rocks have a small hole drilled\" width=\"300\" height=\"268\"><\/a><figcaption id=\"caption-attachment-2799\" class=\"wp-caption-text\">The rover Curiosity drilled a hole in this rock from Mars, and confirmed the mineral Hematite, as mapped from satellites.<\/figcaption><\/figure>\n<p>Geologists identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> by their physical properties. In the field, where geologists may have limited access to advanced technology and powerful machines, they can still identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> by testing several physical properties: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a> and color, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a>, cleavage and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a>, and some special properties. Only a few common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> make up the majority of Earth's rocks and are usually seen as small grains in rocks. Of the several properties used for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, it is good to consider which will be most useful for identifying them in small grains surrounded by other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/p>\n<h3><b>3.5.1 Luster and Color<\/b><\/h3>\n<figure id=\"attachment_2800\" aria-describedby=\"caption-attachment-2800\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Molly_Hill_molybdenite.jpg\"><img class=\"size-medium wp-image-2800\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Molly_Hill_molybdenite-300x225-1.jpg\" alt=\"The crystal looks like metal.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2800\" class=\"wp-caption-text\">15 mm metallic hexagonal molybdenite crystal from Quebec.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The first thing to notice about a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> is its surface appearance, specifically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a> and color. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">Luster<\/a> describes how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> looks. Metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a> looks like a shiny metal such as chrome, steel, silver, or gold. Submetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a> has a duller appearance. Pewter, for example, shows submetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a>.<\/p>\n<figure id=\"attachment_2801\" aria-describedby=\"caption-attachment-2801\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pewter-plate.jpg\"><img class=\"size-medium wp-image-2801\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pewter-plate-300x280-1.jpg\" alt=\"Antique pewter plate showing a more dull submetallic luster\" width=\"300\" height=\"280\"><\/a><figcaption id=\"caption-attachment-2801\" class=\"wp-caption-text\">Submetallic luster shown on an antique pewter plate.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>Nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a> doesn\u2019t look like a metal and may be described as vitreous (glassy), earthy, silky, pearly, and other surface qualities. Nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> may be shiny, although their vitreous shine is different from metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a>. See the table for descriptions and examples of nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a>.<\/p>\n<table style=\"width: 680px;height: 859px\">\n<tbody>\n<tr style=\"height: 32.625px\">\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">Luster<\/a><\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Image<\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Description<\/span><\/th>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Vitreous\/glassy<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_3669\" aria-describedby=\"caption-attachment-3669\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.23_-Quartz_Bresil.jpg\"><img class=\"size-thumbnail wp-image-195\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.23_-Quartz_Bresil-150x150.jpg\" alt=\"A mass of quartz crystals showing typical six sided habit with points\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3669\" class=\"wp-caption-text\">Quartz crystals<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Surface is shiny like glass<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Earthy\/dull<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2802\" aria-describedby=\"caption-attachment-2802\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.47_earthy_luster_KaolinUSGOV-1.jpg\"><img class=\"size-thumbnail wp-image-2802\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.47_earthy_luster_KaolinUSGOV-1-150x150-1.jpg\" alt=\"Specimen of kaolin, a clay oineral, showing dull or earthy luster\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2802\" class=\"wp-caption-text\">Kaolin specimen showing dull or earthy luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Dull, like dried mud or clay<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Silky<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2803\" aria-describedby=\"caption-attachment-2803\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.48_silky_luster_Selenite_Gips_Marienglas-1.jpg\"><img class=\"wp-image-2803\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.48_silky_luster_Selenite_Gips_Marienglas-1-300x230-1.jpg\" alt=\"Specimen showing silky luster\" width=\"150\" height=\"115\"><\/a><figcaption id=\"caption-attachment-2803\" class=\"wp-caption-text\">Specimen showing silky luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Soft shine like silk fabric<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Pearly<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2804\" aria-describedby=\"caption-attachment-2804\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.49_pearly_luster_Mineral_Mica_GDFL006.jpg\"><img class=\"wp-image-2804\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.49_pearly_luster_Mineral_Mica_GDFL006-300x218-1.jpg\" alt=\"Specimen showing pearly luster like the inside of a clam shell\" width=\"150\" height=\"109\"><\/a><figcaption id=\"caption-attachment-2804\" class=\"wp-caption-text\">Specimen showing pearly luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Like the inside of a clam shell or mother-of-pearl<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Submetallic<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2805\" aria-describedby=\"caption-attachment-2805\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.44_submetallic_Sphalerite4.jpg\"><img class=\"wp-image-2805\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.44_submetallic_Sphalerite4-300x277-1.jpg\" alt=\"Photo of mineral exhibiting submetallic luster\" width=\"150\" height=\"138\"><\/a><figcaption id=\"caption-attachment-2805\" class=\"wp-caption-text\">Submetallic luster on sphalerite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Has the appearance of dull metal,\u00a0like pewter. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> would usually still be considered metallic. Submetallic appearance can occur in metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> because of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1754\">weathering<\/a>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<figure id=\"attachment_2806\" aria-describedby=\"caption-attachment-2806\" style=\"width: 245px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Azurite_in_siltstone_Malbunka_mine_NT.jpg\"><img class=\"size-medium wp-image-2806\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Azurite_in_siltstone_Malbunka_mine_NT-245x300-1.jpg\" alt=\"There are two dark blue disks on white siltstone.\" width=\"245\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2806\" class=\"wp-caption-text\">Azurite is ALWAYS a dark blue color, and has been used for centuries for blue pigment.<\/figcaption><\/figure>\n<p>Surface color may be helpful in identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, although it can be quite variable within the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> family. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a> colors are affected by the main <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> as well as impurities in the crystals. These impurities may be rare <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>\u2014like manganese, titanium, chromium, or lithium\u2014even other molecules that are not normally part of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> formula. For example, the incorporation of water molecules gives <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, which is normally clear, a milky color.<\/p>\n<p>Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> predominantly show a single color. Malachite and azurite are green and blue, respectively, because of their copper content. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> have a predictable range of colors due to elemental substitutions, usually via a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">Feldspars<\/a>, the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in the earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>, are complex, have <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1786\">solid solution<\/a> series, and present several colors including pink, white, green, gray and others. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> also come in several colors, influenced by trace amounts of several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. The same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">element<\/a> may show up as different colors, in different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. With notable exceptions, color is usually not a definitive property of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. For identifying many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. a more reliable indicator is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a>, which is the color of the powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>.<\/p>\n<h3><b>3.5.2 Streak<\/b><\/h3>\n<figure id=\"attachment_2807\" aria-describedby=\"caption-attachment-2807\" style=\"width: 450px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-scaled.jpg\"><img class=\"wp-image-2807\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-300x227-1.jpg\" alt=\"Pyrite showing a black streak on a white streak plate and rhodochrosite with a white streak on a black streak plate\" width=\"450\" height=\"341\"><\/a><figcaption id=\"caption-attachment-2807\" class=\"wp-caption-text\">Different minerals may have different streaks<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">Streak<\/a> examines the color of a powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>, and can be seen when a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> sample is scratched or scraped on an unglazed porcelain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. A paper page in a field notebook may also be used for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> of some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> that are harder than the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> will not show <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a>, but will scratch the porcelain. For these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> test can be obtained by powdering the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> with a hammer and smearing the powder across a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> or notebook paper.<\/p>\n<p>While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> surface colors and appearances may vary, their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> colors can be diagnostically useful. An example of this property is seen in the iron-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> hematite. Hematite occurs in a variety of forms, colors and lusters, from shiny metallic silver to earthy red-brown, and different physical appearances. A hematite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a> is consistently reddish brown, no matter what the original specimen looks like. Iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_973\">sulfide<\/a> or pyrite, is a brassy metallic yellow. Commonly named fool\u2019s gold, pyrite has a characteristic black to greenish-black <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a>.<\/p>\n<h3><b>3.5.3 Hardness<\/b><\/h3>\n<figure id=\"attachment_2808\" aria-describedby=\"caption-attachment-2808\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.51_Mohs_Scale2.jpg\"><img class=\"size-large wp-image-2808\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.51_Mohs_Scale2-1024x714-1.jpg\" alt=\"Chart of Mohs Hardness Scale with minerals arranged in hardness from 1 to 10, also showing common items that correlate with the scale.\" width=\"1024\" height=\"714\"><\/a><figcaption id=\"caption-attachment-2808\" class=\"wp-caption-text\">Mohs Hardness Scale<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">Hardness<\/a> measures the ability of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> to scratch other substances. The Mohs <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">Hardness<\/a> Scale gives a number showing the relative scratch-resistance of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> when compared to a standardized set of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> of increasing hardness. The Mohs scale was developed by German geologist Fredrick Mohs in the early 20th century, although the idea of identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a> goes back thousands of years. Mohs <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a> values are determined by the strength of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>\u2019s atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a>.<\/p>\n<p>The figure shows the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> associated with specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a> values, together with some common items readily available for use in field testing and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> identification. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a> values run from 1 to 10, with 10 being the hardest; however, the scale is not linear. Diamond defines a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a> of 10 and is actually about four times harder than corundum, which is 9. A steel pocketknife blade, which has a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a> value of 5.5, separates between hard and soft <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> on many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> identification keys.<\/p>\n<h3><b>3.5.4 Crystal Habit<\/b><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> can be identified by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a><\/strong>, how their crystals grow and appear in rocks. Crystal shapes are determined by the arrangement of the atoms within the crystal structure. For example, a cubic arrangement of atoms gives rise to a cubic-shaped <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystal. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">Crystal habit<\/a> refers to typically observed shapes and characteristics; however, they can be affected by other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> crystallizing in the same rock. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are constrained so they do not develop their typical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a>, they are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_981\">anhedral<\/a><\/strong>. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_982\">Subhedral<\/a><\/strong> crystals are partially formed shapes. For some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a> is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_983\">euhedral<\/a><\/strong> crystal has a perfectly formed, unconstrained shape. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> crystallize in such tiny crystals, they do not show a specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a> to the naked eye. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, like pyrite, can have an array of different crystal habits, including cubic, dodecahedral, octahedral, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a>. The table lists typical crystal habits of various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/p>\n<table style=\"width: 687px;height: 3774px\">\n<tbody>\n<tr>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">Habit<\/a><\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Image<\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Examples<\/span><\/strong><\/th>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Bladed<\/strong><\/p>\n<p>long and flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2809\" aria-describedby=\"caption-attachment-2809\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Kyanite_crystals.jpg\"><img class=\"wp-image-2809\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Kyanite_crystals-300x225-1.jpg\" alt=\"The crystals are long and rectangular\" width=\"150\" height=\"113\"><\/a><figcaption id=\"caption-attachment-2809\" class=\"wp-caption-text\">Bladed kyanite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">kyanite,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a>, gypsum<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Botryoidal\/mammillary<\/strong><\/p>\n<p>blobby, circular crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2810\" aria-describedby=\"caption-attachment-2810\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Malachite_Kolwezi_Katanga_Congo.jpg\"><img class=\"wp-image-2810\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Malachite_Kolwezi_Katanga_Congo-300x174-1.jpg\" alt=\"The mineral is bulbous\" width=\"150\" height=\"87\"><\/a><figcaption id=\"caption-attachment-2810\" class=\"wp-caption-text\">Malachite from the Congo<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">hematite, malachite, smithsonite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Coating\/laminae\/druse<\/strong><\/p>\n<p>crystals that are small and coat surfaces<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2811\" aria-describedby=\"caption-attachment-2811\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ametyst-geode.jpg\"><img class=\"wp-image-2811\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ametyst-geode-300x200-1.jpg\" alt=\"The rock is hollowed and filled with purple minerals\" width=\"150\" height=\"100\"><\/a><figcaption id=\"caption-attachment-2811\" class=\"wp-caption-text\">Quartz (var. amethyst) geode<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, malachite, azurite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Cubic<\/strong><\/p>\n<p>cube-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2812\" aria-describedby=\"caption-attachment-2812\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.55_Cubic_Calcite-Galena-elm56c.jpg\"><img class=\"wp-image-2812\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.55_Cubic_Calcite-Galena-elm56c-260x300-1.jpg\" alt=\"Cubic crystals of galena, a sulfide of lead\" width=\"150\" height=\"173\"><\/a><figcaption id=\"caption-attachment-2812\" class=\"wp-caption-text\">Cubic crystals of galena<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite, galena, halite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dodecahedral<\/strong><\/p>\n<p>12-sided polygon shapes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2813\" aria-describedby=\"caption-attachment-2813\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.53_habit_dodecahedral_Pyrite_elbe-scaled.jpg\"><img class=\"wp-image-2813\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.53_habit_dodecahedral_Pyrite_elbe-300x195-1.jpg\" alt=\"Crystals of pyrite showing dodecahedral habit\" width=\"150\" height=\"97\"><\/a><figcaption id=\"caption-attachment-2813\" class=\"wp-caption-text\">Pyrite crystals with dodecahedral habit<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">garnet, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dendritic<\/strong><\/p>\n<p>branching crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2814\" aria-describedby=\"caption-attachment-2814\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dendrites01.jpg\"><img class=\"wp-image-2814\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Dendrites01-300x203-1.jpg\" alt=\"The mineral look like a fern. They are black and branching.\" width=\"150\" height=\"101\"><\/a><figcaption id=\"caption-attachment-2814\" class=\"wp-caption-text\">Manganese dendrites, scale in mm.<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">Mn-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxides<\/a>, copper, gold<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_984\">Equant<\/a><\/strong><\/p>\n<p>crystals that do not have a long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2815\" aria-describedby=\"caption-attachment-2815\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Peridot2.jpg\"><img class=\"wp-image-209\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Peridot2-272x300.jpg\" alt=\"The crystal is light green.\" width=\"150\" height=\"165\"><\/a><figcaption id=\"caption-attachment-2815\" class=\"wp-caption-text\">Large olivine crystal<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a>, garnet, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Fibrous<\/strong><\/p>\n<p>thin, very long crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2816\" aria-describedby=\"caption-attachment-2816\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tremolite_Campolungo.jpg\"><img class=\"wp-image-2816\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tremolite_Campolungo-300x186-1.jpg\" alt=\"It is white and fiberous\" width=\"150\" height=\"93\"><\/a><figcaption id=\"caption-attachment-2816\" class=\"wp-caption-text\">Tremolite, a type of amphibole<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">serpentine, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a>, zeolite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Layered, sheets<\/strong><\/p>\n<p>stacked, very thin, flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2817\" aria-describedby=\"caption-attachment-2817\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.18_Muscovite-Albite-122887.jpg\"><img class=\"wp-image-2817\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.18_Muscovite-Albite-122887-300x254-1.jpg\" alt=\"Sheets of muscovite mica in crystal mass\" width=\"150\" height=\"127\"><\/a><figcaption id=\"caption-attachment-2817\" class=\"wp-caption-text\">Sheet crystals of muscovite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica <\/a>(<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">biotite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">muscovite<\/a>, etc.)<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Lenticular\/platy<\/strong><\/p>\n<p>crystals that are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>-like<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2818\" aria-describedby=\"caption-attachment-2818\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-Wulfenite-tcw15b.jpg\"><img class=\"wp-image-2818\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Calcite-Wulfenite-tcw15b-251x300-1.jpg\" alt=\"The orange wulfenite is bladed\" width=\"150\" height=\"179\"><\/a><figcaption id=\"caption-attachment-2818\" class=\"wp-caption-text\">Orange wulfenite on calcite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">selenite roses, wulfenite, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Hexagonal<\/strong><\/p>\n<p>crystals with six sides<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_3687\" aria-describedby=\"caption-attachment-3687\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite-1.jpg\"><img class=\"wp-image-213 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hanksite-1-150x150.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3687\" class=\"wp-caption-text\">Hexagonal hanksite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a>, hanksite, corundum<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">Massive<\/a>\/granular<\/strong><\/p>\n<p>Crystals with no obvious shape, microscopic crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2789\" aria-describedby=\"caption-attachment-2789\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img class=\"wp-image-2789\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"150\" height=\"128\"><\/a><figcaption id=\"caption-attachment-2789\" class=\"wp-caption-text\">Limonite, a hydrated oxide of iron<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">limonite, pyrite, azurite, bornite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Octahedral<\/strong><\/p>\n<p>4-sided double pyramid crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2819\" aria-describedby=\"caption-attachment-2819\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90.jpg\"><img class=\"wp-image-2819\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90-300x182-1.jpg\" alt=\"Perfedt octahedral cleavage in fluorite generates octagon-shaped cleavage flakes.\" width=\"150\" height=\"91\"><\/a><figcaption id=\"caption-attachment-2819\" class=\"wp-caption-text\">Octagonal cleavage in fluorite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">diamond, fluorite, magnetite, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Prismatic\/columnar<\/strong><\/p>\n<p>very long, cylindrical crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2820\" aria-describedby=\"caption-attachment-2820\" style=\"width: 142px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tourmaline.jpg\"><img class=\"size-medium wp-image-2820\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tourmaline-142x300-1.jpg\" alt=\"The mineral is a long cylinder.\" width=\"142\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2820\" class=\"wp-caption-text\">Columnar tourmaline<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">tourmaline, beryl, barite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Radiating<\/strong><\/p>\n<p>crystals that grow from a point and fan out<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2821\" aria-describedby=\"caption-attachment-2821\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pyrophyllite-236595.jpg\"><img class=\"wp-image-2821\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pyrophyllite-236595-217x300-1.jpg\" alt=\"The mineral is orange\" width=\"150\" height=\"207\"><\/a><figcaption id=\"caption-attachment-2821\" class=\"wp-caption-text\">Pyrophyllite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite \"suns\", pyrophyllite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Rhombohedral<\/strong><\/p>\n<p>crystals shaped like slanted cubes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2785\" aria-describedby=\"caption-attachment-2785\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img class=\"wp-image-2785\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"150\" height=\"183\"><\/a><figcaption id=\"caption-attachment-2785\" class=\"wp-caption-text\">Calcite crystal in shape of rhomb.<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, dolomite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tabular\/blocky\/stubby<\/strong><\/p>\n<p>sharp-sided crystals with no long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2770\" aria-describedby=\"caption-attachment-2770\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img class=\"wp-image-2770\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"150\" height=\"116\"><\/a><figcaption id=\"caption-attachment-2770\" class=\"wp-caption-text\">Crystals of diopside, a member of the pyroxene family<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tetrahedral<\/strong><\/p>\n<p>three-sided, pyramid-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2822\" aria-describedby=\"caption-attachment-2822\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedrite-Chalcopyrite-Sphalerite-251531.jpg\"><img class=\"wp-image-2822\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tetrahedrite-Chalcopyrite-Sphalerite-251531-300x218-1.jpg\" alt=\"The dark brown mineral is triangular\" width=\"150\" height=\"109\"><\/a><figcaption id=\"caption-attachment-2822\" class=\"wp-caption-text\">Tetrahedrite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">magnetite, spinel, tetrahedrite<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2824\" aria-describedby=\"caption-attachment-2824\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/GypsumStriations.jpg\"><img class=\"wp-image-2824\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/GypsumStriations-251x300-1.jpg\" alt=\"The mineral has many parallel lines on it\" width=\"150\" height=\"179\"><\/a><figcaption id=\"caption-attachment-2824\" class=\"wp-caption-text\">Gypsum with striations<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2823\" aria-describedby=\"caption-attachment-2823\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Staurolite-62645.jpg\"><img class=\"wp-image-2823\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Staurolite-62645-279x300-1.jpg\" alt=\"The brown minerals are replicated in different directions\" width=\"150\" height=\"161\"><\/a><figcaption id=\"caption-attachment-2823\" class=\"wp-caption-text\">Twinned staurolite<\/figcaption><\/figure>\n<p>Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a> that may be used to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> is striations, which are dark and light parallel lines on a crystal face. Twinning is another, which occurs when the crystal structure replicates in mirror images along certain directions in the crystal.<\/p>\n<figure id=\"attachment_2825\" aria-describedby=\"caption-attachment-2825\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img class=\"size-medium wp-image-2825\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\"><\/a><figcaption id=\"caption-attachment-2825\" class=\"wp-caption-text\">Striations on plagioclase<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Striations and twinning are related properties in some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>. Striations are optical lines on a cleavage surface. Because of twinning in the crystal, striations show up on one of the two cleavage faces of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> crystal.<\/p>\n<h3><b>3.5.5 Cleavage and Fracture<\/b><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> often show characteristic patterns of breaking along specific cleavage planes or show characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a> patterns. Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as reflective surfaces on the crystal, as parallel cracks that penetrate into the crystal, or show on the edge or side of the crystal as a series of steps like rice terraces. Cleavage arises in crystals where the atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> between atomic layers are weaker along some directions than others, meaning they will break preferentially along these planes.\u00a0Because they develop on atomic surfaces in the crystal, cleavage planes are optically smooth and reflect light, although the actual break on the crystal may appear jagged or uneven. In such cleavages, the cleavage surface may appear like rice terraces on a mountainside that all reflect sunlight from a particular sun angle. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> have a strong cleavage, some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> only have weak cleavage or do not typically demonstrate cleavage.<\/p>\n<figure id=\"attachment_2826\" aria-describedby=\"caption-attachment-2826\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.57_conchoidal_Citrine-sample2.jpg\"><img class=\"size-medium wp-image-2826\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.57_conchoidal_Citrine-sample2-300x225-1.jpg\" alt=\"A specimen of a variety of quartz showing conchoidal fracture\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2826\" class=\"wp-caption-text\">Citrine, a variety of quartz showing conchoidal fracture<\/figcaption><\/figure>\n<p>For example, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">olivine<\/a> rarely show cleavage and typically break into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a> patterns.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2827\" aria-describedby=\"caption-attachment-2827\" style=\"width: 452px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/cryview_graphite_v1.gif\"><img class=\"wp-image-2827 size-full\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/cryview_graphite_v1.gif\" alt=\"Structure of graphite, showing single carbon layers with weak bonds holding them together\" width=\"452\" height=\"504\"><\/a><figcaption id=\"caption-attachment-2827\" class=\"wp-caption-text\">Graphite showing layers of carbon atoms separated by a gap with weak bonds holding the layers together.<\/figcaption><\/figure>\n<p>Graphite has its carbon atoms arranged into layers with relatively strong <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> within the layer and very weak <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> between the layers.\u00a0 Thus graphite cleaves readily between the layers and the layers slide easily over one another giving graphite its lubricating quality.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a> surfaces may be rough and uneven or they may be show <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a>. Uneven <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a> patterns are described as irregular, splintery, fibrous. A conchoidal fracture has a smooth, curved surface like a shallow bowl or conch shell, often with curved ridges. Natural <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> glass, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_999\">obsidian<\/a>, breaks with this characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_987\">conchoidal<\/a> pattern<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2828\" aria-describedby=\"caption-attachment-2828\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.64_galena_cleavage_Argentiferous_Galena-458851.jpg\"><img class=\"wp-image-2828 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.64_galena_cleavage_Argentiferous_Galena-458851-300x261-1.jpg\" alt=\"Specimen of galena showing cubic cleavage\" width=\"300\" height=\"261\"><\/a><figcaption id=\"caption-attachment-2828\" class=\"wp-caption-text\">Cubic cleavage of galena; note how the cleavage surfaces show up as different but parallel layers in the crystal.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>To work with cleavage, it is important to remember that cleavage is a result of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a> separating along planes of atoms in the crystal structure. On some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, <strong>cleavage planes<\/strong> may be confused with crystal faces. This will usually not be an issue for crystals of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that grew together within rocks. The act of breaking the rock to expose a fresh face will most likely break the crystals along cleavage planes. Some cleavage planes are parallel with crystal faces but many are not.\u00a0Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as parallel cracks that penetrate into the crystal (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a> below), or show on the edge or side of the crystal as a series of steps like rice terraces. For some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a> is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">quartz<\/a> below).<\/p>\n<figure id=\"attachment_2829\" aria-describedby=\"caption-attachment-2829\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img class=\"size-medium wp-image-2829\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2829\" class=\"wp-caption-text\">Freely growing quartz crystals showing crystal faces<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, distinguishing cleavage planes from crystal faces may be challenging for the student. Understanding the nature of cleavage and referring to the number of cleavage planes and cleavage angles on identification keys should provide the student with enough information to distinguish cleavages from crystal faces. Cleavage planes may show as multiple parallel cracks or flat surfaces on the crystal. Cleavage planes may be expressed as a series of steps like terraced rice paddies. See the cleavage surfaces on galena above or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> below. Cleavage planes arise from the tendency of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> crystals to break along specific planes of weakness within the crystal favored by atomic arrangements. The number of cleavage planes, the quality of the cleavage surfaces, and the angles between them are diagnostic for many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and cleavage is one of the most useful properties for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. Learning to recognize cleavage is an especially important and useful skill in studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>.<\/span><\/p>\n<figure id=\"attachment_2830\" aria-describedby=\"caption-attachment-2830\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.61_Cleavage_steps_in_wollastonite.jpg\"><img class=\"size-medium wp-image-2830\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.61_Cleavage_steps_in_wollastonite-300x224-1.jpg\" alt=\"Image of wollastonite, a crystal showing step-like cleavage on one side. All steps are along the same direction of cleavage.\" width=\"300\" height=\"224\"><\/a><figcaption id=\"caption-attachment-2830\" class=\"wp-caption-text\">Steps of cleavage along the same cleavage direction<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2831\" aria-describedby=\"caption-attachment-2831\" style=\"width: 220px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.63_cleavage_in_Amphibole.jpg\"><img class=\"wp-image-2831\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.63_cleavage_in_Amphibole-295x300-1.jpg\" alt=\"Photomicrograph showing 120\/60 degree cleavage in amphibole\" width=\"220\" height=\"224\"><\/a><figcaption id=\"caption-attachment-2831\" class=\"wp-caption-text\">Photomicrograph showing 120\/60 degree cleavage within a grain of amphibole<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>As an identification property of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, cleavage is usually given in terms of the quality of the cleavage (perfect, imperfect, or none), the number of cleavage surfaces, and the angles between the surfaces.\u00a0The most common number of cleavage plane directions in the common rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are: one perfect cleavage (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a>), two cleavage planes (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">pyroxene<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">amphibole<\/a>), and three cleavage planes (as in halite, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>, and galena). One perfect cleavage (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">mica<\/a>) develops on the top and bottom of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> specimen with many parallel cracks showing on the sides but no angle of intersection. Two cleavage planes intersect at an angle. Common cleavage angles are 60\u00b0, 75\u00b0, 90\u00b0, and 120\u00b0.\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">Amphibole<\/a> has two cleavage planes at\u00a060\u00b0 and\u00a0120\u00b0. Galena and halite have three cleavage planes at 90\u00b0 (cubic cleavage). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a> cleaves readily in three directions producing a cleavage figure called a rhomb that looks like a cube squashed over toward one corner giving rise to the approximately 75\u00b0 cleavage angles. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">Pyroxene<\/a> has an imperfect cleavage with two planes at 90\u00b0.<\/p>\n<p><strong>Cleavages on common rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a><\/strong><\/p>\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_967\">Quartz<\/a>\u2014none (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a>)<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1789\">Olivine<\/a>\u2014none (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a>)<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_966\">Mica<\/a>\u20141 perfect<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">Feldspar<\/a>\u20142 perfect at 90\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1790\">Pyroxene<\/a>\u20142 imperfect at 90\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1791\">Amphibole<\/a>\u20142 perfect at 60\u00b0\/120\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">Calcite<\/a>\u20143 perfect at approximately 75\u00b0<\/li>\n<li>Halite, galena, pyrite\u20143 perfect at 90\u00b0<\/li>\n<\/ul>\n<h3><b>3.5.6 Special Properties <\/b><\/h3>\n<figure id=\"attachment_2832\" aria-describedby=\"caption-attachment-2832\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ulexit_Fernsehstein.jpg\"><img class=\"size-thumbnail wp-image-2832\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ulexit_Fernsehstein-150x150-1.jpg\" alt=\"The words on the page are projected upwards onto the mineral\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2832\" class=\"wp-caption-text\">A demonstration of ulexite's image projection<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Special properties are unique and identifiable characteristics used to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> or that allow some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> to be used for special purposes.\u00a0<\/span>Ulexite has a fiber-optic property that can project images through the crystal like a high-definition television screen (see figure). A simple identifying special property is taste, such as the salty flavor of halite or common table salt (NaCl). Sylvite is potassium chloride (KCl) and has a more bitter taste.<\/p>\n<figure id=\"attachment_2833\" aria-describedby=\"caption-attachment-2833\" style=\"width: 225px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Latrobe_gold_nugget_Natural_History_Museum.jpg\"><img class=\"size-medium wp-image-2833\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Latrobe_gold_nugget_Natural_History_Museum-225x300-1.jpg\" alt=\"The nugget is gold\" width=\"225\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2833\" class=\"wp-caption-text\">Native gold has one of the highest specific gravities.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Another property geologists may use to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> is a property related to density called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_989\">specific gravity<\/a><\/strong>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_989\">Specific gravity<\/a> measures the weight of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> specimen relative to the weight of an equal volume of water. The value is expressed as a ratio between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> and water weights. To measure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_989\">specific gravity<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> specimen is first weighed in grams then submerged in a graduated cylinder filled with pure water at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>. The rise in water level is noted using the cylinder\u2019s graduated scale. Since the weight of water at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> is 1 gram per cubic centimeter, the ratio of the two weight numbers gives the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_989\">specific gravity<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_989\">Specific gravity<\/a> is easy to measure in the laboratory but is less useful for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> identification in the field than other more easily observed properties, except in a few rare cases such as the very dense galena or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> gold. The high density of these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> gives rise to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1725\">qualitative<\/a> property called \u201cheft.\u201d Experienced geologists can roughly assess <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_989\">specific gravity<\/a> by heft, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1723\">subjective<\/a> quality of how heavy the specimen feels in one\u2019s hand relative to its size.<\/p>\n<p>A simple test for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> and dolomite is to drop a bit of dilute hydrochloric acid (10-15% HCl) on the specimen. If the acid drop effervesces or fizzes on the surface of the rock, the specimen is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a>. If it does not, the specimen is scratched to produce a small amount of powder and test with acid again. If the acid drop fizzes slowly on the powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>, the specimen is dolomite. The difference between these two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> can be seen in the video. Geologists who work with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> rocks carry a small dropper bottle of dilute HCl in their field kit. Vinegar, which contains acetic acid, can be used for this test and is used to distinguish non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_970\">calcite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a> from limestone. While acidic, vinegar produces less of a fizzing reaction because acetic acid is a weaker acid.<\/p>\n<figure id=\"attachment_3750\" aria-describedby=\"caption-attachment-3750\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-and-Dolomite-YouTube-QR-Code.png\"><img class=\"size-thumbnail wp-image-228\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Calcite-and-Dolomite-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3750\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<figure id=\"attachment_2834\" aria-describedby=\"caption-attachment-2834\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Magnetite_Lodestone.jpg\"><img class=\"size-medium wp-image-2834\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Magnetite_Lodestone-300x200-1.jpg\" alt=\"The paperclip is sticking up into the air.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2834\" class=\"wp-caption-text\">Paperclips attach to lodestone (magnetite).<\/figcaption><\/figure>\n<p>Some iron-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are magnetic and are attracted to magnets. A common name for a naturally magnetic iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_971\">oxide<\/a> is <strong>lodestone<\/strong>. Others include magnetite (Fe3O<sub>4<\/sub>) and ilmenite (FeTiO<sub>3<\/sub>). Magnetite is strongly attracted to magnets and can be magnetized. Ilmenite and some types of hematite are weakly magnetic.<\/p>\n<figure id=\"attachment_2825\" aria-describedby=\"caption-attachment-2825\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img class=\"wp-image-2825 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\"><\/a><figcaption id=\"caption-attachment-2825\" class=\"wp-caption-text\">Iridescence on plagioclase; also showing striations on the cleavage surface<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> and mineraloids scatter light via a phenomenon called <strong>iridescence<\/strong>. This property occurs in labradorite (a variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a>) and opal. It is also seen in biologically created substances like pearls and seashells. Cut diamonds show iridescence and the jeweler\u2019s diamond cut is designed to maximize this property.<\/span><\/p>\n<figure id=\"attachment_2835\" aria-describedby=\"caption-attachment-2835\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD.jpg\"><img class=\"size-medium wp-image-2835\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD-300x217-1.jpg\" alt=\"Image showing exsolution lamellae in potassium feldspar. These are separations of sodium feldspar from potassium feldspar within the crystal, not striations.\" width=\"300\" height=\"217\"><\/a><figcaption id=\"caption-attachment-2835\" class=\"wp-caption-text\">Exsolution lamellae within potassium feldspar<\/figcaption><\/figure>\n<p><strong>Striations<\/strong> on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> cleavage faces are an optical property that can be used to separate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> from potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">K-spar<\/a>). A process called twinning creates parallel zones in the crystal that are repeating mirror images. The actual cleavage angle in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a> is slightly different than 90<sup>o<\/sup> and the alternating mirror images in these twinned zones produce a series of parallel lines on one of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">plagioclase<\/a>\u2019s two cleavage faces. Light reflects off these twinned lines at slightly different angles which then appear as light and dark lines called striations on the cleavage surface.\u00a0Potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> does not exhibit twinning or striations but may show linear features called <strong>exsolution lamellae<\/strong>, also known as perthitic lineation or simply perthite. Because sodium and potassium do not fit into the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> crystal structure, the lines are created by small amounts of sodium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> (albite) separating from the dominant potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspar<\/a> (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">K-spar<\/a>) within the crystal structure. The two different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_968\">feldspars<\/a> crystallize out into roughly parallel zones within the crystal, which are seen as these linear markings.<\/p>\n<figure id=\"attachment_2793\" aria-describedby=\"caption-attachment-2793\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img class=\"size-medium wp-image-2793\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2793\" class=\"wp-caption-text\">Fluorite. B shows fluorescence of fluorite under UV light<\/figcaption><\/figure>\n<p>One of the most interesting special <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> properties is <strong>fluorescence<\/strong>. Certain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, or \u00a0trace <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> within them, give off visible light when exposed to ultraviolet radiation or black light. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a> exhibits have a fluorescence room equipped with black lights so this property can be observed. An even rarer optical property is phosphorescence. <strong>Phosphorescent<\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> absorb light and then slowly release it, much like a glow-in-the-dark sticker.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-23\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-23\" class=\"h5p-iframe\" data-content-id=\"23\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"4.2 Schematic diagram of plutonic and volcanic structures and processes (Source: Woudloper).\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3749\" aria-describedby=\"caption-attachment-3749\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.5-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-231\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3749\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.5 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 18pt\"><strong>Summary<\/strong><\/span><\/h2>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> are the building blocks of rocks and essential to understanding geology. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Mineral<\/a> properties are determined by their atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bonds<\/a>. Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> begin in a fluid, and either crystallize out of cooling <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1785\">precipitate<\/a> as ions and molecules out of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1784\">saturated<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1783\">solution<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> are largest group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> on Earth, by number of varieties and relative quantity, making up a large portion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>. Based on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1788\">silicon-oxygen tetrahedra<\/a>, the crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicates<\/a> reflects the fact that silicon and oxygen are the top two of Earth\u2019s most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. Non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> are also economically important, and providing many types of construction and manufacturing materials. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">Minerals<\/a> are identified by their unique physical properties, including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_977\">luster<\/a>, color, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_978\">streak<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_979\">hardness<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_980\">crystal habit<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a>, cleavage, and special properties.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-22\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-22\" class=\"h5p-iframe\" data-content-id=\"22\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 3 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3748\" aria-describedby=\"caption-attachment-3748\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ch.3-Review-QR-Code.png\"><img class=\"size-thumbnail wp-image-232\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.3-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3748\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 3 via this QR Code.<\/figcaption><\/figure>\n<h2><b>References<\/b><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n<li class=\"csl-entry\">Clarke, F.W.H.S.W., 1927, The Composition of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">Crust<\/a>: Professional Paper, United States Geological Survey, Professional Paper.<\/li>\n<li class=\"csl-entry\">Gordon, L.M., and Joester, D., 2011, Nanoscale chemical tomography of buried organic-inorganic interfaces in the chiton tooth: Nature, v. 469, no. 7329, p. 194\u2013197.<\/li>\n<li class=\"csl-entry\">Hans Wedepohl, K., 1995, The composition of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a>: Geochim. Cosmochim. Acta, v. 59, no. 7, p. 1217\u20131232.<\/li>\n<li class=\"csl-entry\">Lambeck, K., 1986, Planetary evolution: banded iron formations: v. 320, no. 6063, p. 574\u2013574.<\/li>\n<li class=\"csl-entry\">metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> | chemistry.<\/li>\n<li class=\"csl-entry\">Scerri, E.R., 2007, The Periodic Table: Its Story and Its Significance: Oxford University Press, USA.<\/li>\n<li class=\"csl-entry\">Thomson, J.J., 1897, XL. Cathode Rays: Philosophical Magazine Series 5, v. 44, no. 269, p. 293\u2013316.<\/li>\n<li class=\"csl-entry\">Trenn, T.J., Geiger, H., Marsden, E., and Rutherford, E., 1974, The Geiger-Marsden Scattering Results and Rutherford\u2019s Atom, July 1912 to July 1913: The Shifting Significance of Scientific Evidence: Isis, v. 65, no. 1, p. 74\u201382.<\/li>\n<\/ol>\n<\/div>\n<p><span style=\"font-weight: 400\">\u00a0<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_228\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_228\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2012\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2012\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_966\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_966\"><div tabindex=\"-1\"><p>By Michele Buzzi, Studio Cicero. [<a href=\"http:\/\/www.gnu.org\/copyleft\/fdl.html\">GFDL<\/a>, <a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\">CC-BY-SA-3.0<\/a> or <a href=\"http:\/\/creativecommons.org\/licenses\/by\/2.5\">CC BY 2.5<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AMarblequarry.JPG\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2003\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2003\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_967\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_967\"><div tabindex=\"-1\"><p>By Hermann Luyken (Own work) [<a href=\"http:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">CC0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3A2012.10.02.111543_Bonneville_Salt_Flats_Utah.jpg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2005\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2005\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1935\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1935\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2008\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2008\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2009\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2009\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_224\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_224\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2011\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2011\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1006\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1006\"><div tabindex=\"-1\"><p>A process where an oceanic plate descends bellow a less dense plate, causing the removal of the plate from the surface. Subduction causes the largest earthquakes possible, as the subducting plate can lock as it goes down. Volcanism is also caused as the plate releases volatiles into the mantle, causing melting.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2013\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2013\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2014\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2014\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1912\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1912\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1754\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1754\"><div tabindex=\"-1\"><p>Large metallic mineral deposit that forms near magma bodies like plutons. Commonly contains copper, lead, zinc, molybdenum, and gold.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_970\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_970\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2015\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2015\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_991\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_991\"><div tabindex=\"-1\"><p>A piece of foreign rock that has been incorporated into a magma body. This can be a different type of magma, or a mantle xenolith, a rock from the mantle brought up near the surface.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1915\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1915\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2016\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2016\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2019\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2019\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2018\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2018\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1991\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1991\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1722\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1722\"><div tabindex=\"-1\"><p>Data which is out of the ordinary and does not fit previous trends.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2024\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2024\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2021\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2021\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_510\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_510\"><div tabindex=\"-1\"><p>USGS image<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1756\"><div tabindex=\"-1\"><p>Carbonate rock that reacts with hot magmatic fluids, creating concentrated ore deposits, which include copper, iron, zinc, and gold.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_492\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_492\"><div tabindex=\"-1\"><p>Photo by Foto Chd (german wikipedia, https:\/\/de.wikipedia.org\/wiki\/Benutzer:Chd), used under the terms of the GNU Free Documentation License<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1905\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1905\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1760\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1760\"><div tabindex=\"-1\"><p>Diagenetic copper deposit within sedimentary rocks.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1917\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1917\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2038\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2038\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2273\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2273\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1261\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1261\"><div tabindex=\"-1\"><p>Discernible layers of rock, typically from a sedimentary rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1751\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1751\"><div tabindex=\"-1\"><p>Metallic mineral deposit consisting of mafic plutonic rocks, typically containing platinum-group elements, chromium, copper, nickel, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_969\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_969\"><div tabindex=\"-1\"><p>Rob Lavinsky, <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/www.irocks.com\/\">iRocks.com<\/a> \u2013 CC-BY-SA-3.0 [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AApatite-(CaF)-280343.jpg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1791\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1791\"><div tabindex=\"-1\"><figure id=\"attachment_2498\" aria-describedby=\"caption-attachment-2498\" style=\"width: 2048px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/MT3.jpg\"><img class=\"wp-image-67 size-full\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/MT3.jpg\" alt=\"The rock is getting thinner farther away.\" width=\"2048\" height=\"1536\"><\/a><figcaption id=\"caption-attachment-2498\" class=\"wp-caption-text\">A layer of shallow ocean limestone (white) has been brought to the top of a mountain by the convergent forces of the Sevier Orogeny. Near Sun River Canyon, Montana.<\/figcaption><\/figure>\n<h1>2 Plate Tectonics<\/h1>\n<p><b>KEY CONCEPTS<\/b><\/p>\n<p><b>At the end of this chapter, students should be able to:<\/b><\/p>\n<ul>\n<li>Describe how the ideas behind <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> started with Alfred Wegener\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a>\u00a0drift<\/li>\n<li>Describe the physical and chemical layers of the Earth and how they affect <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement<\/li>\n<li>Explain how movement at the three types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> boundaries causes earthquakes, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a>, and mountain building<\/li>\n<li>Identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">convergent<\/a> boundaries, including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> and collisions, as places where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>\u00a0come together<\/li>\n<li>Identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries, including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifts<\/a>\u00a0and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a>, as places where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> separate<\/li>\n<li>Explain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundaries as places where adjacent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">shear<\/a> past each other<\/li>\n<li>Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1715\">Wilson Cycle<\/a>, beginning with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a>, ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> creation, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>, and ending with ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> closure<\/li>\n<li>Explain how the tracks of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a>, places that have continually rising <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>, is used to calculate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> motion<\/li>\n<\/ul>\n<figure id=\"attachment_2499\" aria-describedby=\"caption-attachment-2499\" style=\"width: 4898px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Tectonic_plates_boundaries_detailed-en.svg_.png\"><img class=\"size-full wp-image-68\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tectonic_plates_boundaries_detailed-en.svg_.png\" alt=\"The map shows many plates.\" width=\"4898\" height=\"2461\"><\/a><figcaption id=\"caption-attachment-2499\" class=\"wp-caption-text\">Detailed map of all known plates, their boundaries, and movements.<\/figcaption><\/figure>\n<p>Revolution is a word usually reserved for significant political or social changes. Several of these idea revolutions forced scientists to re-examine their entire field, triggering a paradigm shift that shook up their conventionally held knowledge. Charles Darwin\u2019s book on evolution, <em>On the Origin of Species<\/em>, published in 1859; Gregor Mendel\u2019s discovery of the genetic principles of inheritance in 1866; and James Watson, Francis Crick, and Rosalind Franklin\u2019s model for the structure of DNA in 1953 did that for biology. Albert Einstein\u2019s relativity and quantum mechanics concepts in the early twentieth century did the same for Newtonian physics.<\/p>\n<p>The concept of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> was just as revolutionary for geology. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> attributes the movement of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a> sections of the Earth\u2019s outer layers with creating earthquakes, mountains, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a>. Many earth processes make more sense when viewed through the lens of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a>. Because it is so important in understanding how the world works, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> is the first topic of discussion in this textbook.<\/p>\n<h2><span style=\"font-weight: 400;\">2.1 Alfred Wegener\u2019s Continental Drift Hypothesis<\/span><\/h2>\n<figure id=\"attachment_2500\" aria-describedby=\"caption-attachment-2500\" style=\"width: 195px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Alfred_Wegener_ca.1924-30-2.jpg\"><img class=\"size-full wp-image-28\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Alfred_Wegener_ca.1924-30-2.jpg\" alt=\"He is a male in a suit.\" width=\"195\" height=\"240\"><\/a><figcaption id=\"caption-attachment-2500\" class=\"wp-caption-text\">Wegener later in his life, ca. 1924-1930.<\/figcaption><\/figure>\n<p>Alfred Wegener (1880-1930) was a German scientist who specialized in meteorology and climatology. His knack for questioning accepted ideas started in 1910 when he disagreed with the explanation that the Bering Land Bridge was formed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_753\">isostasy<\/a>, and that similar land bridges once connected the continents. After reviewing the scientific literature, he published a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> stating the continents were originally connected, and then drifted apart. While he did not have the precise mechanism worked out, his <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> was backed up by a long list of evidence.<\/p>\n<h3><\/h3>\n<h3><b>2.1.1 Early Evidence for Continental Drift Hypothesis<\/b><\/h3>\n<figure id=\"attachment_2501\" aria-describedby=\"caption-attachment-2501\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Antonio_Snider-Pellegrini_Opening_of_the_Atlantic.jpg\"><img class=\"size-medium wp-image-69\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Antonio_Snider-Pellegrini_Opening_of_the_Atlantic-300x177.jpg\" alt=\"It shows South America and Africa connected, then apart.\" width=\"300\" height=\"177\"><\/a><figcaption id=\"caption-attachment-2501\" class=\"wp-caption-text\">Snider-Pellegrini's map showing the continental fit and separation, 1858.<\/figcaption><\/figure>\n<p>Wegener\u2019s first piece of evidence was that the coastlines of some continents fit together like pieces of a jigsaw puzzle. People noticed the similarities in the coastlines of South America and Africa on the first world maps, and some suggested the continents had been ripped apart. Antonio Snider-Pellegrini did preliminary work on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> separation and matching <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a> in 1858.<\/p>\n<figure id=\"attachment_2502\" aria-describedby=\"caption-attachment-2502\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/ElevationWorld.jpg\"><img class=\"size-medium wp-image-70\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/ElevationWorld-300x150.jpg\" alt=\"The shape of the continents is different than what is seen by just coastlines.\" width=\"300\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2502\" class=\"wp-caption-text\">Map of world elevations. Note the light blue, which are continental shelves flooded by shallow ocean water. These show the true shapes of the continents.<\/figcaption><\/figure>\n<p>What Wegener did differently was synthesize a large amount of data in one place. He used true edges of the continents, based on the shapes of the continental shelves. This resulted in a better fit than previous efforts that traced the existing coastlines.<\/p>\n<figure id=\"attachment_3259\" aria-describedby=\"caption-attachment-3259\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Wegener_fossil_map.svg_.png\"><img class=\"size-medium wp-image-71\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wegener_fossil_map.svg_-300x231.png\" alt=\"There are four different fossil organisms that connect South America, Africa, India, Antartica, and Australia.\" width=\"300\" height=\"231\"><\/a><figcaption id=\"caption-attachment-3259\" class=\"wp-caption-text\">Image showing fossils that connect the continents of Gondwana (the southern continents of Pangea).<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Wegener also compiled evidence by comparing similar rocks, mountains, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a>, and glacial formations across oceans. For example, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a> of the primitive aquatic reptile <em>Mesosaurus<\/em> were found on the separate coastlines of Africa and South America. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">Fossils<\/a> of another reptile, <em>Lystrosaurus,<\/em> were found on Africa, India, and Antarctica. He pointed out these were land-dwelling creatures could not have swum across an entire ocean.<\/p>\n<p>Opponents of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> drift insisted trans-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic <\/a> land bridges allowed animals and plants to move between continents. The land bridges eventually eroded away, leaving the continents permanently separated. The problem with this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> is the improbability of a land bridge being tall and long enough to stretch across a broad, deep ocean.<\/p>\n<p>More support for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> drift came from the puzzling evidence that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1516\">glaciers<\/a> once existed in normally very warm areas in southern Africa, India, Australia, and Arabia. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_757\">climate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_765\">anomalies<\/a> could not be explained by land bridges. Wegener found similar evidence when he discovered tropical plant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossils<\/a> in the frozen region of the Arctic Circle. As Wegener collected more data, he realized the explanation that best fit all the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_757\">climate<\/a>, rock, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1228\">fossil<\/a> observations involved moving continents.<\/p>\n<h3><b>2.1.2 Proposed Mechanism for Continental Drift<\/b><\/h3>\n<figure id=\"attachment_2504\" aria-describedby=\"caption-attachment-2504\" style=\"width: 400px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Convection.gif\"><img class=\"wp-image-72 size-full\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Convection.gif\" alt=\"The rising material is drawn red. The cool material is blue.\" width=\"400\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2504\" class=\"wp-caption-text\">Animation of the basic idea of convection: an uneven heat source in a fluid causes rising material next to the heat and sinking material far from the heat.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Wegener\u2019s work was considered a fringe science <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a> for his entire life. One of the biggest flaws in his <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> was an inability to provide a mechanism for how the continents moved. Obviously, the continents did not appear to move, and changing the conservative minds of the scientific community would require exceptional evidence that supported a credible mechanism. Other pro-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> drift followers used expansion, contraction, or even the moon\u2019s origin to explain how the continents moved. Wegener used centrifugal forces and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_749\">precession<\/a>, but this model was proven wrong. He also speculated about seafloor spreading, with hints of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a>, but could not substantiate these proposals. As it turns out, current scientific knowledge reveals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> is one the major forces in driving <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movements, along with gravity and density.<\/p>\n<h3><b>2.1.3 Development of Plate Tectonic Theory<\/b><\/h3>\n<figure id=\"attachment_2505\" aria-describedby=\"caption-attachment-2505\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Global_plate_motion_2008-04-17.jpg\"><img class=\"size-medium wp-image-73\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Global_plate_motion_2008-04-17-300x212.jpg\" alt=\"The map shows many data points all over the world.\" width=\"300\" height=\"212\"><\/a><figcaption id=\"caption-attachment-2505\" class=\"wp-caption-text\">GPS measurements of plate motions.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Wegener died in 1930 on an expedition in Greenland. Poorly respected in his lifetime, Wegener and his ideas about moving continents seemed destined to be lost in history as fringe science. However, in the 1950s, evidence started to trickle in that made <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> drift a more viable idea. By the 1960s, scientists had amassed enough evidence to support the missing mechanism\u2014namely, seafloor spreading\u2014for Wegener\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> drift to be accepted as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a>. Ongoing GPS and earthquake data analyses continue to support this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a>. The next section provides the pieces of evidence that helped <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> one man\u2019s wild notion into a scientific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a>.<\/p>\n<h4><span style=\"font-weight: 400;\">Mapping of the Ocean Floors<\/span><\/h4>\n<figure id=\"attachment_2506\" aria-describedby=\"caption-attachment-2506\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Deep_sea_vent_chemistry_diagram.jpg\"><img class=\"size-medium wp-image-74\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_sea_vent_chemistry_diagram-300x174.jpg\" alt=\"The diagram shows water going into the ground and coming out, with many different reactions.\" width=\"300\" height=\"174\"><\/a><figcaption id=\"caption-attachment-2506\" class=\"wp-caption-text\">The complex chemistry around mid-ocean ridges.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>In 1947 researchers started using an adaptation of SONAR to map a region in the middle of the Atlantic Ocean with poorly-understood topographic and thermal properties. Using this information, Bruce Heezen and Marie Tharp created the first detailed map of the ocean floor to reveal the Mid-Atlantic Ridge, a basaltic mountain range that spanned the length of the Atlantic Ocean, with rock chemistry and dimensions unlike the mountains found on the continents. Initially scientists thought the ridge was part of a mechanism that explained the expanding Earth or ocean-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> growth <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypotheses<\/a>. In 1959, Harry Hess proposed the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> of seafloor spreading \u2013 that the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> represented <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> factories, where new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> was issuing from these long <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> ridges. Scientists later included <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> faults perpendicular to the ridges to better account for varying rates of movement between the newly formed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. When earthquake epicenters were discovered along the ridges, the idea that earthquakes were linked to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement took hold.<\/p>\n<div style=\"height: 0; padding-bottom: 56.25%;\">\n<\/div>\n<figure id=\"attachment_3739\" aria-describedby=\"caption-attachment-3739\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Marie-Tharp-YouTube-QR-Code.png\"><img class=\"size-thumbnail wp-image-75\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Marie-Tharp-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3739\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p>Seafloor <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediment<\/a>, measured by dredging and drilling, provided another clue. Scientists once believed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediment<\/a> accumulated on the ocean floors over a very long time in a static environment. When some studies showed less <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediment<\/a> than expected, these results were initially used to argue against <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> movement. With more time, researchers discovered these thinner <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediment<\/a> layers were located close to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a>, indicating the ridges were younger than the surrounding ocean floor. This finding supported the idea that the sea floor was not fixed in one place.<\/p>\n<h4><span style=\"font-weight: 400;\">Paleomagnetism<\/span><\/h4>\n<figure id=\"attachment_2507\" aria-describedby=\"caption-attachment-2507\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Earths_magnetic_field_schematic.svg_.png\"><img class=\"size-medium wp-image-76\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earths_magnetic_field_schematic.svg_-300x250.png\" alt=\"The north end of the magnet is south topographically, and vice versa.\" width=\"300\" height=\"250\"><\/a><figcaption id=\"caption-attachment-2507\" class=\"wp-caption-text\">The magnetic field of Earth, simplified as a bar magnet.<\/figcaption><\/figure>\n<p>The seafloor was also mapped magnetically. Scientists had long known of strange magnetic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_765\">anomalies<\/a> that formed a striped pattern of symmetrical rows on both sides of mid-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> ridges. What made these features unusual was the north and south magnetic poles within each stripe was reversed in alternating rows. By 1963, Harry Hess and other scientists used these magnetic reversal patterns to support their model for seafloor spreading (see also Lawrence W. Morley).<\/p>\n<figure id=\"attachment_2508\" aria-describedby=\"caption-attachment-2508\" style=\"width: 351px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Earth_Magnetic_Field_Declination_from_1590_to_1990.gif\"><img class=\"wp-image-77 size-full\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth_Magnetic_Field_Declination_from_1590_to_1990.gif\" alt=\"The poles shift slightly every year.\" width=\"351\" height=\"293\"><\/a><figcaption id=\"caption-attachment-2508\" class=\"wp-caption-text\">This animation shows how the magnetic poles have moved over 400 years.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1657\">Paleomagnetism<\/a> is the study of magnetic fields frozen within rocks, basically a fossilized compass. In fact, the first hard evidence to support <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> motion came from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1657\">paleomagnetism<\/a>.<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">Igneous<\/a> rocks containing magnetic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> like magnetite typically provide the most useful data. In their liquid state as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1751\">lava<\/a>, the magnetic poles of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> align themselves with the Earth\u2019s magnetic field. When the rock cools and solidifies, this alignment is frozen into place, creating a permanent paleomagnetic record that includes magnetic inclination related to global latitude, and declination related to magnetic north.<\/p>\n<figure id=\"attachment_2509\" aria-describedby=\"caption-attachment-2509\" style=\"width: 240px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/02.1-magnetic_stripes.gif\"><img class=\"size-full wp-image-78\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/02.1-magnetic_stripes.gif\" alt=\"Animated gif depicting a mid-ocean ridge with two oceanic plates moving away from the center of the ridge. As the movement progresses, symettrical magnetic stripes appear on each side of the ridge.\" width=\"240\" height=\"180\"><\/a><figcaption id=\"caption-attachment-2509\" class=\"wp-caption-text\">The iron in the solidifying rock preserves the current magnetic polarity as new oceanic plates form at mid ocean ridges<\/figcaption><\/figure>\n<p>Scientists had noticed for some time the alignment of magnetic north in many rocks was nowhere close to the earth\u2019s current magnetic north. Some explained this away are part of the normal movement of earth\u2019s magnetic north pole. Eventually, scientists realized adding the idea of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> movement explained the data better than pole movement alone.<\/p>\n<h4><\/h4>\n<h4><\/h4>\n<h4><span style=\"font-weight: 400;\">Wadati-Benioff Zones<\/span><\/h4>\n<figure id=\"attachment_2510\" aria-describedby=\"caption-attachment-2510\" style=\"width: 297px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/benioff_zone.gif\"><img class=\"size-full wp-image-79\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/benioff_zone.gif\" alt=\"The earthquakes descend at an angle into the Earth.\" width=\"297\" height=\"243\"><\/a><figcaption id=\"caption-attachment-2510\" class=\"wp-caption-text\">The Wadati-Benioff zone, showing earthquakes following the subducting slab down.<\/figcaption><\/figure>\n<p>Around the same time <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> were being investigated, other scientists linked the creation of ocean trenches and island arcs to seismic activity and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement. Several independent research groups recognized earthquake epicenters traced the shapes of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> sinking into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>. These deep earthquake zones congregated in planes that started near the surface around ocean trenches and angled beneath the continents and island arcs. Today these earthquake zones called Wadati-Benioff zones.<\/p>\n<figure id=\"attachment_2511\" aria-describedby=\"caption-attachment-2511\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/John_Tuzo_Wilson_in_1992-2.jpg\"><img class=\"size-medium wp-image-39\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/John_Tuzo_Wilson_in_1992-2-244x300.jpg\" alt=\"He is an older man in this 1992 image.\" width=\"244\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2511\" class=\"wp-caption-text\">J. Tuzo Wilson<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Based on the mounting evidence, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> continued to take shape. J. Tuzo Wilson was the first scientist to put the entire picture together by proposing that the opening and closing of the ocean basins. Before long, scientists proposed other models showing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> moving with respect to each other, with clear boundaries between them. Others started piecing together complicated histories of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> revolution had taken hold.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div id=\"h5p-8\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-8\" class=\"h5p-iframe\" data-content-id=\"8\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Continental Drift vs. Plate Tectonics\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3738\" aria-describedby=\"caption-attachment-3738\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Continental-Drive-Activity-QR-Code.png\"><img class=\"size-thumbnail wp-image-80\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Continental-Drive-Activity-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3738\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this interactive activity via this QR Code.<\/figcaption><\/figure>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-9\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-9\" class=\"h5p-iframe\" data-content-id=\"9\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"2.1 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3737\" aria-describedby=\"caption-attachment-3737\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/2.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-81\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/2.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3737\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 2.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400;\">2.2 Layers of the Earth<\/span><\/h2>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2512\" aria-describedby=\"caption-attachment-2512\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Earth-cutaway-schematic-english.svg_-1.png\"><img class=\"size-medium wp-image-51\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-300x211.png\" alt=\"The crust and lithosphere are on the outside of the Earth and are thin. Below the crust is the mantle and core. Below the lithosphere is the asthenosphere.\" width=\"300\" height=\"211\"><\/a><figcaption id=\"caption-attachment-2512\" class=\"wp-caption-text\">The layers of the Earth. Physical layers include lithosphere and asthenosphere; chemical layers are crust, mantle, and core.<\/figcaption><\/figure>\n<p>In order to understand the details of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a>, it is essential to first understand the layers of the earth. Firsthand information about what is below the surface is very limited; most of what we know is pieced together from hypothetical models, and analyzing seismic wave data and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1254\">meteorite<\/a> materials. In general, the Earth can be divided into layers based on chemical composition and physical characteristics.<\/p>\n<h3><b>2.2.1 Chemical Layers<\/b><\/h3>\n<p>Certainly the earth is composed of a countless combination of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a>. Regardless of what <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1778\">elements<\/a> are involved two major factors\u2014<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and pressure\u2014are responsible for creating three distinct chemical layers.<\/p>\n<h4><span style=\"font-weight: 400;\">Crust<\/span><\/h4>\n<p>The outermost chemical layer and the one we currently reside on, is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. There are two types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">Continental crust<\/a> has a relatively low density and composition similar to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1014\">granite<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">Oceanic crust<\/a> has a relatively high density, especially when cold and old, and composition similar to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1013\">basalt<\/a>. The surface levels of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> are relatively <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1661\">brittle<\/a>. The deeper parts of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> are subjected to higher temperatures and pressure, which makes them more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1660\">ductile<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1660\">Ductile<\/a> materials are like soft plastics or putty, they move under force. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1661\">Brittle<\/a> materials are like solid glass or pottery, they break under force, especially when it is applied quickly. Earthquakes, generally occur in the upper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> and are caused by the rapid movement of relatively <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1661\">brittle<\/a> materials.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2513\" aria-describedby=\"caption-attachment-2513\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/MohoDepth-1.png\"><img class=\"size-medium wp-image-50\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MohoDepth-1-300x167.png\" alt=\"Places with mountain building have a deeper moho.\" width=\"300\" height=\"167\"><\/a><figcaption id=\"caption-attachment-2513\" class=\"wp-caption-text\">The global map of the depth of the moho.<\/figcaption><\/figure>\n<p>The base of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> is characterized by a large increase in seismic velocity, which measures how fast earthquake waves travel through solid matter. Called the Mohorovi\u010di\u0107 Discontinuity, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1662\">Moho<\/a> for short, this zone was discovered by Andrija Mohorovi\u010di\u0107 (pronounced mo-ho-ro-vee-cheech; <a href=\"https:\/\/www.merriam-webster.com\/dictionary\/Mohorovicic%20discontinuity\">audio pronunciation<\/a>) in 1909 after studying earthquake wave paths in his <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_976\">native<\/a> Croatia. The change in wave direction and speed is caused by dramatic chemical differences of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>. Underneath the oceans, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1662\">Moho<\/a> is found roughly 5 km below the ocean floor. Under the continents, it is located about 30-40 km below the surface. Near certain large mountain-building events known as orogenies, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1662\">Moho<\/a> depth is doubled.<\/p>\n<h4><span style=\"font-weight: 400;\">Mantle<\/span><\/h4>\n<figure id=\"attachment_2514\" aria-describedby=\"caption-attachment-2514\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Iddingsite.jpg\"><img class=\"size-medium wp-image-82\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Iddingsite-300x225.jpg\" alt=\"The xenolith sits on top of a basalt rock. It has three sides like a pyramid; one of the sides is more altered to iddingsite.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2514\" class=\"wp-caption-text\">This mantle xenolith containing olivine (green) is chemically weathering by hydrolysis and oxidation into the pseudo-mineral iddingsite, which is a complex of water, clay, and iron oxides. The more altered side of the rock has been exposed to the environment longer.<\/figcaption><\/figure>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> sits below the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> and above the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a>. It is the largest chemical layer by volume, extending from the base of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> to a depth of about 2900 km. Most of what we know about the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> comes from seismic wave analysis, though information is gathered by studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1700\">ophiolites<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1665\">xenoliths<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1700\">Ophiolites<\/a> are pieces of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> that have risen through the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> until they are exposed as part of the ocean floor. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1665\">Xenoliths<\/a> are carried within <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> and brought to the Earth\u2019s surface by volcanic eruptions. Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1665\">xenoliths<\/a> are made of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1666\">peridotite<\/a>, an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1009\">ultramafic<\/a> class of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1753\">igneous rock<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes#4-2BowensReaction\" target=\"_blank\" rel=\"noopener\">chapter 4.2<\/a> for explanation). Because of this, scientists hypothesize most of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> is made of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1666\">peridotite<\/a>.<\/p>\n<h4><span style=\"font-weight: 400;\">Core<\/span><\/h4>\n<figure id=\"attachment_2515\" aria-describedby=\"caption-attachment-2515\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/02.2_TolucaMeteorite.jpg\"><img class=\"size-medium wp-image-83\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/02.2_TolucaMeteorite-300x225.jpg\" alt=\"The meteorite is polished showing the Widmanst\u00e4tten Pattern.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2515\" class=\"wp-caption-text\">A polished fragment of the iron-rich Toluca Meteorite, with octahedral Widmanst\u00e4tten Pattern.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> of the Earth, which has both liquid and solid layers, and consists mostly of iron, nickel, and possibly some oxygen. Scientists looking at seismic data first discovered this innermost chemical layer in 1906. Through a union of hypothetical modeling, astronomical insight, and hard seismic data, they concluded the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> is mostly metallic iron. Scientists studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1254\">meteorites<\/a>, which typically contain more iron than surface rocks, have proposed the earth was formed from meteoric material. They believe the liquid component of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> was created as the iron and nickel sank into the center of the planet, where it was liquefied by intense pressure.<\/p>\n<h3><b>2.2.2 Physical Layers<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">The Earth can also be broken down into five distinct physical layers based on how each layer responds to stress. While there is some overlap in the chemical and physical designations of layers, specifically the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a>-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> boundary, there are significant differences between the two systems.<\/span><\/p>\n<h4><span style=\"font-weight: 400;\">Lithosphere<\/span><\/h4>\n<figure id=\"attachment_2516\" aria-describedby=\"caption-attachment-2516\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Plates_tect2_en.svg_-2.png\"><img class=\"size-medium wp-image-49\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Plates_tect2_en.svg_-2-300x205.png\" alt=\"There are about 10 major plates\" width=\"300\" height=\"205\"><\/a><figcaption id=\"caption-attachment-2516\" class=\"wp-caption-text\">Map of the major plates and their motions along boundaries.<\/figcaption><\/figure>\n<p><em>Lithos<\/em> is Greek for stone, and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is the outermost physical layer of the Earth. It is grouped into two types: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">Oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is thin and relatively rigid. It ranges in thickness from nearly zero in new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> found around <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a>, to an average of 140 km in most other locations. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">Continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is generally thicker and considerably more plastic, especially at the deeper levels. Its thickness ranges from 40 to 280 km. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is not continuous. It is broken into segments called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1670\">plate boundary<\/a> is where two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> meet and move relative to each other. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">Plate<\/a> boundaries are where we see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> in action\u2014mountain building, triggering earthquakes, and generating <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> activity.<\/p>\n<h4><span style=\"font-weight: 400;\">Asthenosphere<\/span><\/h4>\n<figure id=\"attachment_2517\" aria-describedby=\"caption-attachment-2517\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Earths_Inner_Layers_denoting_the_LAB.png\"><img class=\"size-medium wp-image-84\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earths_Inner_Layers_denoting_the_LAB-300x207.png\" alt=\"It is thin at a mid-ocean ridge, thick under collisions\" width=\"300\" height=\"207\"><\/a><figcaption id=\"caption-attachment-2517\" class=\"wp-caption-text\">The lithosphere-asthenosphere boundary changes with certain tectonic situations.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a> is the layer below the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>. <em>Astheno-<\/em> means lacking strength, and the most distinctive property of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a> is movement. Because it is mechanically weak, this layer moves and flows due to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> currents created by heat coming from the earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> cause. Unlike the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> that consists of multiple <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a> is relatively unbroken. Scientists have determined this by analyzing seismic waves that pass through the layer. The depth of at which the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a> is found is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>-dependent. It tends to lie closer to the earth\u2019s surface around <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> and much deeper underneath mountains and the centers of lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>.<\/p>\n<h4><span style=\"font-weight: 400;\">Mesosphere<\/span><\/h4>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2518\" aria-describedby=\"caption-attachment-2518\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Perovskite.jpg\"><img class=\"size-medium wp-image-85\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Perovskite-300x288.jpg\" alt=\"The atoms are arranged.\" width=\"300\" height=\"288\"><\/a><figcaption id=\"caption-attachment-2518\" class=\"wp-caption-text\">General perovskite structure. Perovskite silicates (i.e.<br \/>Bridgmenite,<br \/>(Mg,Fe)SiO3) are thought to be the main component of the lower mantle, making it the most common mineral in or on Earth.<\/figcaption><\/figure>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1672\">mesosphere<\/a>, sometimes known as the lower <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>, is more rigid and immobile than the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a>. Located at a depth of approximately 410 and 660 km below the earth\u2019s surface, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1672\">mesosphere<\/a> is subjected to very high pressures and temperatures. These extreme conditions create a transition zone in the upper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1672\">mesosphere<\/a> where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> continuously change into various forms, or pseudomorphs. Scientists identify this zone by changes in seismic velocity and sometimes physical barriers to movement. Below this transitional zone, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1672\">mesosphere<\/a> is relatively uniform until it reaches the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a>.<\/p>\n<h4><span style=\"font-weight: 400;\">Inner and Outer Core<\/span><\/h4>\n<figure id=\"attachment_2519\" aria-describedby=\"caption-attachment-2519\" style=\"width: 206px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Inge_Lehmann_1932.jpg\"><img class=\"size-medium wp-image-86\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Inge_Lehmann_1932-206x300.jpg\" alt=\"Is shows her as a young woman\" width=\"206\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2519\" class=\"wp-caption-text\">Lehmann in 1932<\/figcaption><\/figure>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a> is the only entirely liquid layer within the Earth. It starts at a depth of 2,890 km and extends to 5,150 km, making it about 2,300 km thick. In 1936, the Danish geophysicist Inge Lehmann analyzed seismic data and was the first to prove a solid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1674\">inner core<\/a> existed within a liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a> . The solid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1674\">inner core<\/a> is about 1,220 km thick, and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a> is about 2,300 km thick.<\/p>\n<p>It seems like a contradiction that the hottest part of the Earth is solid, as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> making up the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> should be liquified or vaporized at this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>. Immense pressure keeps the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1674\">inner core<\/a> in a solid phase. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1674\">inner core<\/a> grows slowly from the lower <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a> solidifying as heat escapes the interior of the Earth and is dispersed to the outer layers.<\/p>\n<figure id=\"attachment_2520\" aria-describedby=\"caption-attachment-2520\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/02.2_SpinningOuterCore.gif\"><img class=\"size-medium wp-image-87\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/02.2_SpinningOuterCore-300x289.gif\" alt=\"The Earth is cut out with the core being shown.\" width=\"300\" height=\"289\"><\/a><figcaption id=\"caption-attachment-2520\" class=\"wp-caption-text\">The outer core's spin causes our protective magnetic field.<\/figcaption><\/figure>\n<p>The earth\u2019s liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a> is critically important in maintaining a breathable <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a> and other environmental conditions favorable for life. Scientists believe the earth\u2019s magnetic field is generated by the circulation of molten iron and nickel within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a>. If the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1673\">outer core<\/a> were to stop circulating or become solid, the loss of the magnetic field would result in Earth getting stripped of life-supporting gases and water. This is what happened, and continues to happen, on Mars.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div id=\"h5p-10\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-10\" class=\"h5p-iframe\" data-content-id=\"10\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Layers of the Earth practice\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3736\" aria-describedby=\"caption-attachment-3736\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Layers-of-Earth-Practice-QR-Code.png\"><img class=\"size-thumbnail wp-image-88\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Layers-of-Earth-Practice-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3736\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this interactive activity via this QR Code.<\/figcaption><\/figure>\n<h3><b>2.2.3 Plate Tectonic Boundaries<\/b><\/h3>\n<figure id=\"attachment_2521\" aria-describedby=\"caption-attachment-2521\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Passive_Contiental_Margin.jpg\"><img class=\"size-medium wp-image-89\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Passive_Contiental_Margin-300x143.jpg\" alt=\"The plate thins from continent to ocean\" width=\"300\" height=\"143\"><\/a><figcaption id=\"caption-attachment-2521\" class=\"wp-caption-text\">Passive margin<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>At passive margins the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> don\u2019t move\u2014the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> transitions into oceanic lithosphere and forms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> made of both types. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> may be made of both <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> connected by a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1676\">passive margin<\/a>. North and South America\u2019s eastern coastlines are examples of passive margins. Active margins are places where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> meet and move relative to each other, such as the western coasts of North and South America. This movement is caused by frictional drag created between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> and differences in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> densities. The majority of mountain-building events, earthquake activity and active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> on the Earth\u2019s surface can be attributed to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement at active margins.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2522\" aria-describedby=\"caption-attachment-2522\" style=\"width: 775px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Tectonic_plate_boundaries.png\"><img class=\"size-full wp-image-90\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tectonic_plate_boundaries.png\" alt=\"It shows all the types\" width=\"775\" height=\"429\"><\/a><figcaption id=\"caption-attachment-2522\" class=\"wp-caption-text\">Schematic of plate boundary types.<\/figcaption><\/figure>\n<p>In a simplified model, there are three categories of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> boundaries. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">Convergent<\/a> boundaries are places where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> move toward each other. At <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> move apart. At <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundaries, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> slide past each other.<\/p>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-11\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-11\" class=\"h5p-iframe\" data-content-id=\"11\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"2.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3735\" aria-describedby=\"caption-attachment-3735\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/2.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-91\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/2.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3735\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 2.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 28px;\">2.3 Convergent Boundaries<\/span><\/h2>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2523\" aria-describedby=\"caption-attachment-2523\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/CratonGeolProv.jpg\"><img class=\"size-medium wp-image-92\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CratonGeolProv-300x159.jpg\" alt=\"The legend shows shields, platforms, orogens, basins, large igneous provinces, and extended crust.\" width=\"300\" height=\"159\"><\/a><figcaption id=\"caption-attachment-2523\" class=\"wp-caption-text\">Geologic provinces with the Shield (orange) and Platform (pink) comprising the Craton, the stable interior of continents.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">Convergent<\/a> boundaries, also called destructive boundaries, are places where two or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> move toward each other. . <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">Convergent<\/a> boundary movement is divided into two types, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a>, depending on the density of the involved <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">Continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is of lower density and thus more buoyant than the underlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">Oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is more dense than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>, and, when old and cold, may even be more dense than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a>.<\/p>\n<p>When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> of different densities converge, the higher density <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> is pushed beneath the more buoyant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> in a process called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> converge without <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> occurring, this process is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a>.<\/p>\n<h3><b>2.3.1. Subduction<\/b><\/h3>\n<div style=\"width: 720px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-461-1\" width=\"720\" height=\"540\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/Subduction.mp4?_=1\" \/><a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/Subduction.mp4\">http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/Subduction.mp4<\/a><\/video><\/div>\n<p><em><a href=\"http:\/\/emvc.geol.ucsb.edu\/2_infopgs\/IP1GTect\/cSubduction.html\">Video<\/a> showing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\"><em>continental<\/em><\/a>-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\"><em>oceanic <\/em><\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\"><em>subduction<\/em><\/a>, causing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\"><em>volcanism<\/em><\/a>. By Tanya Atwater and John Iwerks.<\/em><\/p>\n<figure id=\"attachment_3734\" aria-describedby=\"caption-attachment-3734\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Subduction-Animation-QR-Code.png\"><img class=\"size-thumbnail wp-image-93\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Subduction-Animation-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3734\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this video via this QR Code.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">Subduction<\/a> occurs when a dense <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> meets a more buoyant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, like a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> or warmer\/younger <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, and descends into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>. The worldwide average rate of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> is 25 miles per million years, about a half-inch per year. As an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> descends, it pulls the ocean floor down into a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1681\">trench<\/a>. These trenches can be more than twice as deep as the average depth of the adjacent ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a>, which is usually three to four km. The Mariana <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1681\">Trench<\/a>, for example, approaches a staggering 11 km.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2524\" aria-describedby=\"caption-attachment-2524\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Subduction-en.svg_.png\"><img class=\"size-full wp-image-94\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Subduction-en.svg_.png\" alt=\"Many features are labeled on the diagram, but the main idea is the ocean plate descending below the continental\" width=\"800\" height=\"391\"><\/a><figcaption id=\"caption-attachment-2524\" class=\"wp-caption-text\">Diagram of ocean-continent subduction.<\/figcaption><\/figure>\n<figure id=\"attachment_2525\" aria-describedby=\"caption-attachment-2525\" style=\"width: 212px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/drawing.png\"><img class=\"size-medium wp-image-95\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/drawing-212x300.png\" alt=\"This drawing depicts a microcontinent riding with a subducting plate, and not being subductable, becoming accreted to the melange.\" width=\"212\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2525\" class=\"wp-caption-text\">Microcontinents can become part of the accretionary prism of a subduction zone.<\/figcaption><\/figure>\n<p>Within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1681\">trench<\/a>, ocean floor <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">sediments<\/a> are scraped together and compressed between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> and overriding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. This feature is called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1682\">accretionary wedge<\/a>, m\u00e9lange, or accretionary prism. Fragments of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> material, including microcontinents, riding atop the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> may become sutured to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1682\">accretionary wedge <\/a> and accumulate into a large area of land called a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1764\">terrane<\/a>. Vast portions of California are comprised of accreted terranes.<\/p>\n<figure id=\"attachment_2526\" aria-describedby=\"caption-attachment-2526\" style=\"width: 179px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/usgs_terranes.gif\"><img class=\"size-medium wp-image-96\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/usgs_terranes-179x300.gif\" alt=\"Map showing large areas of the western North American continent that are accreted.\" width=\"179\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2526\" class=\"wp-caption-text\">Accreted terranes of western North America. Everything that is not the \"Ancient continental interior (craton)\" has been smeared onto the side of the continent by accretion from subduction.<\/figcaption><\/figure>\n<p>When the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a>, sinks into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>, the immense heat and pressure pushes volatile materials like water and carbon dioxide into an area below the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> and above the descending <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1685\">mantle wedge<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1684\">volatiles<\/a> are released mostly by hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> that revert to non-hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a> in these higher <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and pressure conditions. When mixed with asthenospheric material above the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, the volatile lower the melting point of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1685\">mantle wedge<\/a>, and through a process called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1686\">flux melting<\/a> it becomes liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a>. The molten <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> is more buoyant than the lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> above it and migrates to the Earth\u2019s surface where it emerges as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>. The resulting <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> frequently appear as curved mountain chains, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> arcs, due to the curvature of the earth. Both <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> can contain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> arcs.<\/p>\n<figure id=\"attachment_2527\" aria-describedby=\"caption-attachment-2527\" style=\"width: 236px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/1755_Lisbon_Earthquake_Location.png\"><img class=\"size-medium wp-image-97\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/1755_Lisbon_Earthquake_Location-236x300.png\" alt=\"It is large and offshore.\" width=\"236\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2527\" class=\"wp-caption-text\">Location of the large (Mw 8.5-9.0) 1755 Lisbon Earthquake.<\/figcaption><\/figure>\n<p>How <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> is initiated is still a matter of scientific debate. It is generally accepted that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zones start as passive margins, where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a>\u00a0and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> come together, and then gravity initiates <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> and converts the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1676\">passive margin<\/a> into an active one. One <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> is gravity pulls the denser <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> down or the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> can start to flow ductility at a low angle. Scientists seeking to answer this question have collected evidence that suggests a new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zone is forming off the coast\u00a0of Portugal. Some scientists have proposed large earthquakes like the 1755 Lisbon earthquake may even have something to do with this process of creating a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zone, although the evidence is not definitive. Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> proposes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> happens at <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundaries involving <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> of different densities.<\/p>\n<p>Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> boundaries look like they should be active, but show no evidence of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> on either side of the Atlantic Ocean for example, are denser than the underlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a> and are not <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> beneath the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. One <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1781\">bond<\/a> holding the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> together is stronger than the downwards force created by the difference in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> densities.<\/p>\n<figure id=\"attachment_2528\" aria-describedby=\"caption-attachment-2528\" style=\"width: 234px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/SundaMegathrustSeismicity.png\"><img class=\"size-medium wp-image-98\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/SundaMegathrustSeismicity-234x300.png\" alt=\"The earthquakes follow the slab down.\" width=\"234\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2528\" class=\"wp-caption-text\">Earthquakes along the Sunda megathrust subduction zone, along the island of Sumatra, showing the 2006 Mw 9.1-9.3 Indian Ocean Earthquake as a star.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">Subduction<\/a> zones are known for having the largest earthquakes and tsunamis; they are the only places with fault surfaces large enough to create magnitude-9 earthquakes. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>-zone earthquakes not only are very large, but also are very deep. When a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> becomes stuck and cannot descend, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a> amount of energy builds up between the stuck <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. If this energy is not gradually dispersed, it may force the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> to suddenly release along several hundred kilometers of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zone. Because <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>-zone faults are located on the ocean floor, this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a> amount of movement can generate giant tsunamis such as those that followed the 2004 Indian Ocean Earthquake and 2011 T\u014dhoku Earthquake in Japan.<\/p>\n<figure id=\"attachment_2529\" aria-describedby=\"caption-attachment-2529\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Forearc.gif\"><img class=\"size-medium wp-image-99\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Forearc-300x258.gif\" alt=\"It shows backarc, forearc, and arc.\" width=\"300\" height=\"258\"><\/a><figcaption id=\"caption-attachment-2529\" class=\"wp-caption-text\">Various parts of a subduction zone. This subduction zone is ocean-ocean subduction, though the same features can apply to continent-ocean subduction.<\/figcaption><\/figure>\n<p>All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zones have a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1692\">forearc basin<\/a>, a feature of the overriding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> found between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1695\">volcanic arc<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1681\">trench<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1692\">forearc basin<\/a> experiences a lot of faulting\u00a0and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> activity, particularly within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1682\">accretionary wedge<\/a>.<\/p>\n<p>In some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zones, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">tensional<\/a> forces\u00a0working on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> create a backarc <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> on the interior side of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1695\">volcanic arc<\/a>. Some scientists have proposed a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> mechanism called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> rollback creates <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extension<\/a> faults in the overriding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. In this model, the descending <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> does not slide directly under the overriding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> but instead rolls back, pulling the overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> seaward. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> behind the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1695\">volcanic arc<\/a> gets stretched like pizza dough until the surface cracks and collapses to form a backarc <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a>. If the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extension<\/a> activity is extensive and deep enough, a backarc <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> can develop into a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> zone. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries may be less symmetrical than their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridge<\/a> counterparts.<\/p>\n<p>In places where numerous young buoyant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are converging and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> at a relatively high velocity, they may force the overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> to buckle and crack. This is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1688\">back-arc<\/a> faulting. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">Extensional<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1688\">back-arc<\/a> faults pull rocks and chunks of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> apart. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_493\">Compressional<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1688\">back-arc<\/a> faults, also known as thrust faults, push them together.<\/p>\n<p>The dual spines of the Andes Mountain range include a example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_493\">compressional<\/a> thrust faulting. The western spine is part of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1695\">volcanic arc<\/a>. Thrust faults have deformed the non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> eastern spine, \u00a0pushing rocks and pieces of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> on top of each other.<\/p>\n<p>There are two styles of thrust fault <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a>: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1689\">thin-skinned<\/a> faults that occur in superficial rocks lying on top of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1690\">thick-skinned<\/a> faults that reach deeper into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a>. The Sevier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1663\">Orogeny<\/a> in the western U.S. is a notable <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1689\">thin-skinned<\/a> type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> created during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_487\">Cretaceous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1244\">Period<\/a>. The Laramide <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1663\">Orogeny<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1690\">thick-skinned<\/a> type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a>, occurred near the end of and slightly after the Sevier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1663\">Orogeny<\/a> \u00a0in the same region.<\/p>\n<figure id=\"attachment_2530\" aria-describedby=\"caption-attachment-2530\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Shallow_subduction_Laramide_orogeny.png\"><img class=\"size-medium wp-image-100\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Shallow_subduction_Laramide_orogeny-300x142.png\" alt=\"The subducting plate goes right under the overriding plate\" width=\"300\" height=\"142\"><\/a><figcaption id=\"caption-attachment-2530\" class=\"wp-caption-text\">Shallow subduction during the Laramide Orogeny.<\/figcaption><\/figure>\n<p>Flat-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a>, or shallow, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> caused the Laramide <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1663\">Orogeny<\/a>. When the descending <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducts<\/a> at a low angle, there is more contact between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> and the overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> than in a typical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zone. The shallowly-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> pushes against the overriding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> and creates an area of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> on the overriding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> many kilometers away from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zone.<\/p>\n<h4><span style=\"font-weight: 400;\">Oceanic-Continental subduction<\/span><\/h4>\n<figure id=\"attachment_2531\" aria-describedby=\"caption-attachment-2531\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/OceanContSub.gif\"><img class=\"size-medium wp-image-101\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OceanContSub-300x177.gif\" alt=\"The thinner ocean plate is going under the thicker continental plate.\" width=\"300\" height=\"177\"><\/a><figcaption id=\"caption-attachment-2531\" class=\"wp-caption-text\">Subduction of an oceanic plate beneath a continental plate, forming a trench and volcanic arc.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1694\">Oceanic-continental subduction<\/a> occurs when an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> dives below a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">convergent<\/a> boundary has a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1681\">trench<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1685\">mantle wedge<\/a> and frequently, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1695\">volcanic arc<\/a>. Well-known examples of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1695\">volcanic arcs<\/a> are the Cascade Mountains in the Pacific Northwest and western Andes Mountains in South America.<\/p>\n<h4><span style=\"font-weight: 400;\">Oceanic-Oceanic Subduction<\/span><\/h4>\n<figure id=\"attachment_2532\" aria-describedby=\"caption-attachment-2532\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Fig21oceanocean.gif\"><img class=\"size-medium wp-image-102\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig21oceanocean-300x173.gif\" alt=\"The ocean plate subducts beneath a different ocean plate.\" width=\"300\" height=\"173\"><\/a><figcaption id=\"caption-attachment-2532\" class=\"wp-caption-text\">Subduction of an oceanic plate beneath another oceanic plate, forming a trench and an island arc.<\/figcaption><\/figure>\n<p>The boundaries of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1696\">oceanic-oceanic subduction<\/a> zones show very different activity from those involving <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a>-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. Since both <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are made of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>, it is usually the older <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducts<\/a> because it is colder and denser. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> on the overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> may remain hidden underwater.. If the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> rise high enough the reach the ocean surface, the chain of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> forms an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1697\">island arc<\/a>. Examples of these island arcs include the Aleutian Islands in the northern Pacific Ocean, Lesser Antilles in the Caribbean Sea, and numerous island chains scattered throughout the western Pacific Ocean.<\/p>\n<h3><b>2.3.2. Collisions<\/b><\/h3>\n<figure id=\"attachment_2533\" aria-describedby=\"caption-attachment-2533\" style=\"width: 301px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/contcontCollision.gif\"><img class=\"size-full wp-image-103\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/contcontCollision.gif\" alt=\"The two continental plates stay up.\" width=\"301\" height=\"181\"><\/a><figcaption id=\"caption-attachment-2533\" class=\"wp-caption-text\">Two continental plates colliding.<\/figcaption><\/figure>\n<p>When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> converge, during the closing of an ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> for example, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> is not possible between the equally buoyant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. Instead of one <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> descending beneath another, the two masses of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> slam together in a process known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a>. Without <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>, there is no <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> formation and no <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">Collision<\/a> zones are characterized by tall, non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> mountains; a broad zone of frequent, large earthquakes; and very little <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>.<\/p>\n<p>When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic crust<\/a> connected by a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1676\">passive margin<\/a> to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a> completely <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducts<\/a> beneath a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continent<\/a>, an ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> closes, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a> begins. \u00a0Eventually, as ocean basins close, continents join together to form a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a> accumulation of continents called a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinent<\/a>, a process that has taken place in ~500 million year old cycles over earth\u2019s history.<\/p>\n<figure id=\"attachment_2534\" aria-describedby=\"caption-attachment-2534\" style=\"width: 267px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Pangaea_continents.png\"><img class=\"size-medium wp-image-104\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pangaea_continents-267x300.png\" alt=\"Pangaea has a crescent shape.\" width=\"267\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2534\" class=\"wp-caption-text\">A reconstruction of Pangaea, showing approximate positions of modern continents.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The process of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a> created Pangea, the supercontinent envisioned by Wegener as the key component of his <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> drift <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a>. Geologists now have evidence that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> have been continuously converging into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinents<\/a> and splitting into smaller <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a>-separated continents throughout Earth\u2019s existence, calling this process the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinent<\/a> cycle, a process that takes place in approximately 500 million years. For example, they estimate Pangea began separating 200 million years ago. Pangea was preceded by an earlier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinents<\/a>, one of which being <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1263\">Rodinia<\/a>, which existed 1.1 billion years ago and started breaking apart 800 million to 600 million years ago.<\/p>\n<figure id=\"attachment_2535\" aria-describedby=\"caption-attachment-2535\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/ZagrosFTB.png\"><img class=\"size-medium wp-image-105\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/ZagrosFTB-300x231.png\" alt=\"The mountains are loading the crust down, leading to a depressed basin, which is the Persian Gulf\" width=\"300\" height=\"231\"><\/a><figcaption id=\"caption-attachment-2535\" class=\"wp-caption-text\">The tectonics of the Zagros Mountains. Note the Persian Gulf foreland basin.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>A foreland <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_508\">basin<\/a> is a feature that develops near mountain belts, as the combined mass of the mountains forms a depression in the lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. While foreland basins may occur at <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zones, they are most commonly found at <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a> boundaries. The Persian Gulf is possibly the best modern example, created entirely by the weight of the nearby Zagros Mountains.<\/p>\n<figure id=\"attachment_2536\" aria-describedby=\"caption-attachment-2536\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/02.3_ItalyPillowBasalt.jpg\"><img class=\"size-medium wp-image-106\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/02.3_ItalyPillowBasalt-300x225.jpg\" alt=\"The rock is cray with many circles inside\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2536\" class=\"wp-caption-text\">Pillow lavas, which only form under water, from an ophiolite in the Apennine Mountains of central Italy.<\/figcaption><\/figure>\n<p>If <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> are fused on the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, it can partially subduct but its buoyancy prevents it from fully descending. In very rare cases, part of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> may become trapped beneath a descending <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> in a process called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1699\">obduction<\/a>. When a portion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental crust<\/a> is driven down into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zone, due to its buoyancy it returns to the surface relatively quickly.<\/p>\n<p>As pieces of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> break loose and migrate upward through the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1699\">obduction<\/a> zone, they bring along bits of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> and ocean floor and amend them on top of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. Rocks composed of this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> and ocean-floor material are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1700\">ophiolites<\/a> and they provide valuable information about the composition of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>.<\/p>\n<p>The area of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a>-zone <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a> and seismic activity usually covers a broader area because <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> is plastic and malleable. Unlike <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a>-zone earthquakes, which tend to be located along a narrow swath near the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1678\">convergent<\/a> boundary, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a>-zone earthquakes may occur hundreds of kilometers from the boundary between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>.<\/p>\n<p>The Eurasian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continent<\/a> has many examples of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1698\">collision<\/a>-zone deformations covering vast areas. The Pyrenees mountains begin in the Iberian Peninsula and cross into France. Also, there are the Alps stretching from Italy to central Europe; the Zagros mountains from Arabia to Iran; and Himalaya mountains from the Indian subcontinent to central Asia.<\/p>\n<div style=\"width: 720px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-461-2\" width=\"720\" height=\"478\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/IndiaAsiaCollision.mp4?_=2\" \/><a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/IndiaAsiaCollision.mp4\">http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/IndiaAsiaCollision.mp4<\/a><\/video><\/div>\n<p><em>Animation of India crashing into Asia, by Tanya Atwater.<\/em><\/p>\n<figure id=\"attachment_3733\" aria-describedby=\"caption-attachment-3733\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/India-Asia-Collision-Animation-QR-Code.png\"><img class=\"size-thumbnail wp-image-107\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/India-Asia-Collision-Animation-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3733\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this animation via this QR Code.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-12\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-12\" class=\"h5p-iframe\" data-content-id=\"12\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"2.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3732\" aria-describedby=\"caption-attachment-3732\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/2.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-108\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/2.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3732\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 2.3 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400;\">2.4 Divergent Boundaries<\/span><\/h2>\n<p>At <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries, sometimes called constructive boundaries, lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> move away from each other. There are two types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries, categorized by where they occur: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> zones and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">Continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> zones occur in weak spots in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridge<\/a> usually originates in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> zone that expands to the point of splitting the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> apart, with seawater filling in the gap. The separate pieces continue to drift apart and become individual continents. This process is known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a>-to-drift.<\/p>\n<h3><b>2.4.1. Continental Rifting<\/b><\/h3>\n<figure id=\"attachment_2537\" aria-describedby=\"caption-attachment-2537\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Horst-Graben.svg_.png\"><img class=\"size-medium wp-image-109\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Horst-Graben.svg_-300x154.png\" alt=\"While the area extends, individual grabens drop down relative to the horsts.\" width=\"300\" height=\"154\"><\/a><figcaption id=\"caption-attachment-2537\" class=\"wp-caption-text\">Faulting that occurs in divergent boundaries.<\/figcaption><\/figure>\n<p>In places where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are very thick, they reflect so much heat back into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> it develops strong <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> currents that push super-heated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> material up against the overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, softening it. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">Tensional<\/a> forces created by this convective upwelling begin to pull the weakened <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> apart. As it stretches, it becomes thinner and develops deep cracks called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extension<\/a> or normal faults. Eventually plate sections located between large faults drop into deep depressions known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> valleys, which often contain keystone-shaped blocks of down-dropped <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1704\">grabens<\/a>. The shoulders of these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1704\">grabens<\/a> are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1703\">horsts<\/a>. If only one side of a section drops, it is called a half-graben. Depending on the conditions, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifts<\/a> can grow into very large lakes and even oceans.<\/p>\n<figure id=\"attachment_2538\" aria-describedby=\"caption-attachment-2538\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/TopographicAfar.png\"><img class=\"size-medium wp-image-110\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/TopographicAfar-300x300.png\" alt=\"The branches of the plate boundaries are 120 degrees apart.\" width=\"300\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2538\" class=\"wp-caption-text\">The Afar Triangle (center) has the Red Sea ridge (center to upper left), Gulf of Aden ridge (center to right), and East African Rift (center to lower left) form a triple junction that are about 120\u00b0 apart.<\/figcaption><\/figure>\n<p>While seemingly occurring at random, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> is dictated by two factors. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">Rifting<\/a> does not occur in continents with older and more stable interiors, known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1718\">cratons<\/a>. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> does occur, the break-up pattern resembles the seams of a soccer ball, also called a truncated icosahedron. This is the most common surface-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a> pattern to develop on an evenly expanding sphere because it uses the least amount of energy.<\/p>\n<p>Using the soccer ball model, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> tends to lengthen and expand along a particular seam while fizzling out in the other directions. These seams with little or no <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> activity are called failed rift arms. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1705\">failed rift arm<\/a> is still a weak spot in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>; even without the presence of active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extension<\/a> faults, it may develop into a called an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1706\">aulacogen<\/a>. One example of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1705\">failed rift arm<\/a> is the Mississippi Valley Embayment, a depression through which the upper end of the Mississippi River flows. Occasionally connected <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> arms do develop concurrently, creating multiple boundaries of active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a>. In places where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> arms do not fail, for example the Afar Triangle, three <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries can develop near each other forming a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1707\">triple junction<\/a>.<\/p>\n<figure id=\"attachment_2539\" aria-describedby=\"caption-attachment-2539\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Basin_range_province.jpg\"><img class=\"size-medium wp-image-111\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Basin_range_province-300x240.jpg\" alt=\"There is a series of mountains and valleys\" width=\"300\" height=\"240\"><\/a><figcaption id=\"caption-attachment-2539\" class=\"wp-caption-text\">NASA image of the Basin and Range horsts and grabens across central Nevada.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">Rifts<\/a> come in two types: narrow and broad. Narrow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifts<\/a> are characterized by a high density of highly active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries. The East African <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">Rift<\/a> Zone, where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1531\">horn<\/a> of Africa is pulling away from the mainland, is an excellent example of an active narrow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a>. Lake Baikal in Russia is another. Broad <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifts<\/a> also have numerous fault zones, but they are distributed over wide areas of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_495\">deformation<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1514\">Basin and Range<\/a> region located in the western United States is a type of broad <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a>. The Wasatch Fault, which also created the Wasatch Mountain Range in the state of Utah, forms the eastern <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundary of this broad <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a>\u00a0 (<a href=\"https:\/\/youtu.be\/TvvWqAdNV84\">Animation 1<\/a> and <a href=\"https:\/\/youtu.be\/7DxcAMmNeZk\">Animation 2<\/a>).<\/p>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">Rifts<\/a> have earthquakes, although not of the magnitude and frequency of other boundaries. They may also exhibit <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>. Unlike the flux-melted <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zones, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a>-zone <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> is created by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_223\">decompression melting<\/a>. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are pulled apart, they create a region of low pressure that melts the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> and draws it upwards. When this molten <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> reaches the weakened and fault-riddled <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> zone, it migrates to surface by breaking through the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> or escaping via an open fault. Examples of young <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> dot the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1514\">Basin and Range<\/a> region in the United States. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">Rift<\/a>-zone activity is responsible for generating some unique <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>, such as the Ol Doinyo Lengai in Tanzania. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcano<\/a> erupts <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1751\">lava<\/a> consisting largely of carbonatite, a relatively cold, liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_969\">carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">mineral<\/a>.<\/p>\n<div style=\"width: 720px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-461-3\" width=\"720\" height=\"474\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/SoAtlantic_CutwithConvect.mp4?_=3\" \/><a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/SoAtlantic_CutwithConvect.mp4\">http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/SoAtlantic_CutwithConvect.mp4<\/a><\/video><\/div>\n<p>South America and Africa <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a>, forming the Atlantic. <a href=\"http:\/\/emvc.geol.ucsb.edu\/2_infopgs\/IP1GTect\/eSoAtlantic_CutGlobe.html\">Video<\/a> by Tanya Atwater.<\/p>\n<figure id=\"attachment_3731\" aria-describedby=\"caption-attachment-3731\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Rift-Atlantic-Animation-QR-Code.png\"><img class=\"size-thumbnail wp-image-112\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rift-Atlantic-Animation-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3731\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this video via this QR Code.<\/figcaption><\/figure>\n<h3><b>2.4.2. Mid-ocean ridges<\/b><\/h3>\n<figure id=\"attachment_2541\" aria-describedby=\"caption-attachment-2541\" style=\"width: 212px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Ocean-birth.svg_.png\"><img class=\"size-medium wp-image-113\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ocean-birth.svg_-212x300.png\" alt=\"The ocean starts as a valley and then gets wider and wider.\" width=\"212\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2541\" class=\"wp-caption-text\">Progression from rift to mid-ocean ridge.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\">As <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> activity progress, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> becomes more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1008\">mafic<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\" target=\"_blank\" rel=\"noopener\">Chapter 4<\/a>) and thinner, with the eventual result transforming the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> under the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> area into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>. This is the process that gives birth to a new ocean, much like the narrow Red Sea emerged with the movement of Arabia away from Africa. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> continues to diverge, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridge<\/a> is formed.<\/span><\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">Mid-ocean ridges<\/a>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">spreading centers<\/a>, have several distinctive features. They are the only places on earth that create new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_223\">Decompression melting<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> zone changes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a> material into new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>, which oozes up through cracks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. The amount of new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> being created at <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> is highly significant. These undersea <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> produce more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1751\">lava<\/a> than all other types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> combined. Despite this, most mid-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> ridge <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> remains unmapped because the volcanoes are located deep on the ocean floor.<\/p>\n<p>In rare cases, such as a few locations in Iceland, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rift<\/a> zones display the type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>, spreading, and ridge formation found on the ocean floor.<\/p>\n<figure id=\"attachment_2542\" aria-describedby=\"caption-attachment-2542\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/age_oceanic_lith.jpg\"><img class=\"size-medium wp-image-114\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/age_oceanic_lith-300x191.jpg\" alt=\"The map shoes colors that represent different ages.\" width=\"300\" height=\"191\"><\/a><figcaption id=\"caption-attachment-2542\" class=\"wp-caption-text\">Age of oceanic lithosphere, in millions of years. Notice the differences in the Atlantic Ocean along the coasts of the continents.<\/figcaption><\/figure>\n<p>The ridge feature is created by the accumulation of hot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> material, which is lighter than the dense underlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a>. This chunk of isostatically buoyant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> sits partially submerged and partially exposed on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a>, like an ice cube floating in a glass of water.<\/p>\n<p>As the ridge continues to spread, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> material is pulled away from the area of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> and becomes colder and denser. As it continues to spread and cool, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> settles into wide swathes of relatively featureless topography called abyssal plains with lower topography.<\/p>\n<p>This model of ridge formation suggests the sections of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a> furthest away from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> will be the oldest. Scientists have tested this idea by comparing the age of rocks located in various locations on the ocean floor. Rocks found near ridges are younger than those found far away from any ridges. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">Sediment<\/a> accumulation patterns also confirm the idea of sea-floor spreading. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1756\">Sediment<\/a> layers tend to be thinner near <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a>, indicating it has had less time to build up.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2543\" aria-describedby=\"caption-attachment-2543\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/atwater_mag_reversal_mid_ocean_ridge.gif\"><img class=\"wp-image-115 size-full\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/atwater_mag_reversal_mid_ocean_ridge.gif\" alt=\"animation showing the mid ocean ridges. As new oceanic plate is made at the ridge, it cools and preserves the current magnetic field at the time of cooling. When the poles reverse, the magnetic polarity flip is preserved in the oceanic plate record.\" width=\"600\" height=\"400\"><\/a><figcaption id=\"caption-attachment-2543\" class=\"wp-caption-text\">Spreading along several mid-ocean ridges, showing magnetic striping symmetry. By Tanya Atwater.<\/figcaption><\/figure>\n<figure id=\"attachment_3743\" aria-describedby=\"caption-attachment-3743\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Atwater-Spreading-GIF.png\"><img class=\"size-thumbnail wp-image-116\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atwater-Spreading-GIF-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3743\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this animation via this QR Code.<\/figcaption><\/figure>\n<p>As mentioned in the section on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1657\">paleomagnetism<\/a> and the development of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a>, scientists noticed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> contained unique magnetic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_765\">anomalies<\/a> that show up as symmetrical striping on both sides of the ridge. The Vine-Matthews-Morley <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> proposes these alternating reversals are created by the earth\u2019s magnetic field being imprinted into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a><\/p>\n<figure id=\"attachment_2544\" aria-describedby=\"caption-attachment-2544\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Oceanic.Stripe.Magnetic.Anomalies.Scheme.svg_.png\"><img class=\"size-medium wp-image-117\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Oceanic.Stripe.Magnetic.Anomalies.Scheme.svg_-300x212.png\" alt=\"The older stripes are farther from the ridge.\" width=\"300\" height=\"212\"><\/a><figcaption id=\"caption-attachment-2544\" class=\"wp-caption-text\">A time progression (with \"a\" being youngest and \"c\" being oldest) showing a spreading center getting wider while recording changes in the magnetic field of the Earth.<\/figcaption><\/figure>\n<p>after it emerges from the ridge. Very hot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> has no magnetic field. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> get pulled apart, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> cools below the Curie point, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> below which a magnetic field gets locked into magnetic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>. The alternating magnetic reversals in the rocks reflects the periodic swapping of earth\u2019s magnetic north and south poles. This paleomagnetic pattern provides a great historical record of ocean-floor movement, and is used to reconstruct past <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> activity and determine rates of ridge spreading.<\/p>\n<p><em><a href=\"http:\/\/emvc.geol.ucsb.edu\/2_infopgs\/IP3RegTect\/bNoCentAtlantic.html\">Video<\/a> of the breakup of <em>Pangea<\/em> and <em>formation<\/em> of the northern Atlantic Ocean. By Tanya Atwater.<\/em><\/p>\n<figure id=\"attachment_3729\" aria-describedby=\"caption-attachment-3729\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pangea-Animation-QR-Code.png\"><img class=\"size-thumbnail wp-image-118\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pangea-Animation-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3729\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this video via this QR Code.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2545\" aria-describedby=\"caption-attachment-2545\" style=\"width: 233px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/BlackSmoker.jpg\"><img class=\"wp-image-119 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/BlackSmoker-233x300.jpg\" alt=\"There is a large build up of minerals around the vent\" width=\"233\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2545\" class=\"wp-caption-text\">Black smoker hydrothermal vent with a colony of giant (6'+) tube worms.<\/figcaption><\/figure>\n<p>Thanks to their distinctive geology, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> are home to some of the most unique ecosystems ever discovered. The ridges are often studded with hydrothermal vents, deep fissures that allow seawater to circulate through the upper portions of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> and interact with hot rock. The super-heated seawater rises back up to the surface of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, carrying dissolved gasses and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1765\">minerals<\/a>, and small particulates.\u00a0 The resulting emitted hydrothermal water looks like black underwater smoke.<\/p>\n<p>Scientists had known about these geothermal areas on the ocean floor for some time. However, it was not until 1977, when scientists piloting a deep submergence vehicle, the Alvin, discovered a thriving community of organisms clustered around these hydrothermal vents. These unique organisms, which include 10-foot-long tube worms taller than people, live in the complete darkness of the ocean floor  deprived of oxygen and sunlight. They use geothermal energy provided by the vents and a process called bacterial <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_231\">chemosynthesis<\/a> to feed on sulfur compounds. Before this discovery, scientists believed life on earth could not exist without photosynthesis, a process that requires sunlight. Some scientists suggest this type of environment could have been the origin of life on Earth, and perhaps even extraterrestrial life elsewhere in the galaxy, such as on Jupiter\u2019s moon Europa.<\/p>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-13\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-13\" class=\"h5p-iframe\" data-content-id=\"13\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"2.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3728\" aria-describedby=\"caption-attachment-3728\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/2.4-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-120\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/2.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3728\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 2.4 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400;\">2.5 Transform Boundaries<\/span><\/h2>\n<figure id=\"attachment_2546\" aria-describedby=\"caption-attachment-2546\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Strike_slip_fault.png\"><img class=\"size-medium wp-image-121\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Strike_slip_fault-300x137.png\" alt=\"Sinistral moves to the left, dextral moves to the right.\" width=\"300\" height=\"137\"><\/a><figcaption id=\"caption-attachment-2546\" class=\"wp-caption-text\">The two types of transform\/strike slip faults.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundary, sometimes called a strike-slip or conservative boundary, is where the lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> slide past each other in the horizontal plane. This movement is described based on the perspective of an observer standing on one of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>, looking across the boundary at the opposing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. Dextral, also known as right-lateral, movement describes the opposing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> moving to the right. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1710\">Sinistral<\/a>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1710\">left lateral<\/a>, movement describe the opposing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> moving to the left.<\/p>\n<p>Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundaries are found on the ocean floor, around <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a>. These boundaries form aseismic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_986\">fracture<\/a> zones, filled with earthquake-free <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> faults, to accommodate different rates of spreading occurring at the ridge.<\/p>\n<figure id=\"attachment_2547\" aria-describedby=\"caption-attachment-2547\" style=\"width: 217px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Sanandreas.jpg\"><img class=\"size-medium wp-image-122\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Sanandreas-217x300.jpg\" alt=\"The fault runs through California.\" width=\"217\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2547\" class=\"wp-caption-text\">Map of the San Andreas fault, showing relative motion.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundaries produce significant seismic activity, primarily as earthquakes, with very little mountain-building or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>. This type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundary may contain a single fault or series of faults, which develop in places where <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> stresses are transferred to the surface. As with other types of active boundaries, if the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are unable to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">shear<\/a> past each other the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> forces will continue to build up. If the built up energy between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> is suddenly released, the result is an earthquake.<\/p>\n<p>In the eyes of humanity, the most significant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> faults occur within <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>, and have a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">shearing<\/a> motion that frequently produces moderate-to-large magnitude earthquakes. Notable examples include the San Andreas Fault in California, Northern and Eastern Anatolian Faults\u00a0in Turkey, Altyn Tagh Fault in central Asia, and Alpine Fault in New Zealand.<\/p>\n<h3><b>2.5.1. Transpression and Transtension<\/b><\/h3>\n<figure id=\"attachment_2548\" aria-describedby=\"caption-attachment-2548\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Transpression.png\"><img class=\"wp-image-123 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Transpression-150x150.png\" alt=\"The fault is dextral, and has a leftward bend, causing uplift.\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2548\" class=\"wp-caption-text\">A transpressional strike-slip fault, causing uplift called a restraining bend.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Bends along <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> faults may create <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_493\">compressional<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extensional<\/a> forces that cause secondary faulting zones. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1712\">Transpression<\/a> occurs where there is a component of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_493\">compression<\/a> in addition to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">shearing<\/a> motion. These forces build up around the area of the bend, where the opposing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are restricted from sliding past each other. As the forces continue to build up, they create mountains in the restraining bend around the fault. The Big Bend area, located in the southern part of the San Andreas Fault includes a large area of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1712\">transpression<\/a> where many mountains have been built, moved, and even rotated.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2549\" aria-describedby=\"caption-attachment-2549\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Transtension.png\"><img class=\"wp-image-124 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Transtension-150x150.png\" alt=\"The fault is dextral, and has a rightward bend, causing a valley.\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2549\" class=\"wp-caption-text\">A transtensional strike-slip fault, causing a restraining bend. In the center of the fault, a depression with extension would be found.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1713\">Transtension<\/a> zones require a fault that includes a releasing bend, where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are being pulled apart by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_492\">extensional<\/a> forces. Depressions and sometimes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> develop in the releasing bend, along the fault. The Dead Sea found between Israel and Jordan, and the Salton Sea of California are examples of basins formed by transtensional forces.<\/p>\n<h3><\/h3>\n<h3><b>2.5.2. Piercing Points<\/b><\/h3>\n<figure id=\"attachment_2550\" aria-describedby=\"caption-attachment-2550\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Wallace_Creek_offset_across_the_San_Andreas_Fault.png\"><img class=\"size-medium wp-image-125\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wallace_Creek_offset_across_the_San_Andreas_Fault-300x205.png\" alt=\"The offset is to the left.\" width=\"300\" height=\"205\"><\/a><figcaption id=\"caption-attachment-2550\" class=\"wp-caption-text\">Wallace (dry) Creek on the Cariso Plain, California. Note as the creek flows from the northern mountainous part of the image, it takes a sharp right (as viewed from the flow of water), then a sharp left. This is caused by the San Andreas Fault cutting roughly perpendicular to the creek, and shifting the location of the creek over time. The fault can be seen about halfway down, trending left to right, as a change in the topography.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>When a geological feature is cut by a fault, it is called a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1714\">piercing point<\/a>. Piercing points are very useful for recreating past fault movement, especially along <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">transform<\/a> boundaries. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\">Transform<\/a> faults are unique because their horizontal motion keeps a geological feature relatively intact, preserving the record of what happened. Other types of faults\u2014normal and reverse \u2014tend to be more destructive, obscuring or destroying these features. The best type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1714\">piercing point<\/a> includes unique patterns that are used to match the parts of a geological feature separated by fault movement. Detailed studies of piercing points show the San Andreas Fault has experienced over 225 km of movement in the last 20 million years, and this movement occurred at three different fault traces.<\/p>\n<p><em>Video of the origin of the San Andreas <em>fault<\/em>. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\"><em>mid-ocean ridge<\/em><\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\"><em>subducts<\/em><\/a>, the relative motion between the remaining <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\"><em>plates<\/em><\/a> become <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1679\"><em>transform<\/em><\/a>, forming the <em>fault<\/em> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1742\"><em>system<\/em><\/a>. Note that because the motion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\"><em>plates<\/em><\/a> is not exactly parallel to the <em>fault<\/em>, it causes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\"><em>divergent<\/em><\/a> motion in the interior of North America. By Tanya Atwater.<\/em><\/p>\n<figure id=\"attachment_3727\" aria-describedby=\"caption-attachment-3727\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Plate-Tectonics-YouTube-QR-Code.png\"><img class=\"size-thumbnail wp-image-126\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Plate-Tectonics-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3727\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-14\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-14\" class=\"h5p-iframe\" data-content-id=\"14\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"2.5 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3726\" aria-describedby=\"caption-attachment-3726\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/2.5-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-127\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/2.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3726\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 2.5 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400;\">2.6 The Wilson Cycle<\/span><\/h2>\n<figure id=\"attachment_2551\" aria-describedby=\"caption-attachment-2551\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Wilson-cycle_hg.svg_.png\"><img class=\"size-medium wp-image-128\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wilson-cycle_hg.svg_-300x164.png\" alt=\"The diagram shows the last 1000 million years.\" width=\"300\" height=\"164\"><\/a><figcaption id=\"caption-attachment-2551\" class=\"wp-caption-text\">Diagram of the Wilson Cycle, showing rifting and collision phases.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1715\">Wilson Cycle<\/a> is named for J. Tuzo Wilson who first described it in 1966, and it outlines the ongoing origin and breakup of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinents<\/a>, such as Pangea and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1263\">Rodinia<\/a>. Scientists have determined this cycle has been operating for at least three billion years and possibly earlier.<\/p>\n<p>There are a number of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypotheses<\/a> about how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1715\">Wilson Cycle<\/a> works. One mechanism proposes that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> happens because <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> reflect the heat much better than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. When continents congregate together, they reflect more of the Earth\u2019s heat back into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>, generating more vigorous <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> currents that then start the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> process. Some geologists believe <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> plumes are remnants of these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1244\">periods<\/a> of increased <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> upwelling, and study them for clues about the origin of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a>.<\/p>\n<p>The mechanism behind how <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinents<\/a> are created is still largely a mystery. There are three schools of thought about what continues to drive the continents further apart and eventually bring them together. The ridge-push <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">hypothesis<\/a> suggests after the initial <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> event, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> continue to be pushed apart by mid-ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">spreading centers<\/a> and their underlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> currents. Slab-pull proposes the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> are pulled apart by descending slabs in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> zones of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a>-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> margins. A third idea, gravitational sliding, attributes the movement to gravitational forces pulling the lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> down from the elevated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1708\">mid-ocean ridges<\/a> and across the underlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1671\">asthenosphere<\/a>. Current evidence seems to support <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1683\">slab<\/a> pull more than ridge push or gravitational sliding.<\/p>\n<h2><span style=\"font-weight: 400;\">2.7 Hotspots<\/span><\/h2>\n<figure id=\"attachment_2552\" aria-describedby=\"caption-attachment-2552\" style=\"width: 193px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Hotspotgeology-1.svg_.png\"><img class=\"size-medium wp-image-129\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hotspotgeology-1.svg_-193x300.png\" alt=\"The plate is moving to the left, the magma stays in the center am makes a chain of volcanoes.\" width=\"193\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2552\" class=\"wp-caption-text\">Diagram showing a non-moving source of magma (mantle plume) and a moving overriding plate.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1715\">Wilson Cycle<\/a> provides a broad overview of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement. To analyze <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement more precisely, scientists study <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a>. First postulated by J. Tuzo Wilson in 1963, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> is an area in the lithospheric <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> where molten <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> breaks through and creates a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> center, islands in the ocean and mountains on land. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> moves across the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcano<\/a> center becomes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_755\">extinct<\/a> because it is no longer over an active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> source. Instead, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> emerges through another area in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> to create a new active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcano<\/a>. Over time, the combination of moving <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> and stationary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> creates a chain of islands or mountains. The classic definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> states they do not move, although recent evidence suggests that there may be exceptions.<\/p>\n<figure id=\"attachment_2553\" aria-describedby=\"caption-attachment-2553\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/HotspotsWorld.png\"><img class=\"size-medium wp-image-130\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HotspotsWorld-300x175.png\" alt=\"Hotspots are scattered around the world.\" width=\"300\" height=\"175\"><\/a><figcaption id=\"caption-attachment-2553\" class=\"wp-caption-text\">Map of world hotspots. Larger circles indicate more active hotspots.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">Hotspots<\/a> are the only types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> not associated with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subduction<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a> zones at <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> boundaries; they seem totally disconnected from any <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> processes, such as earthquakes. However, there are\u00a0 relationships between <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a>. There are several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a>, current and former, that are believed to have begun at the time of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a>. Also, scientists use the age of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> eruptions and shape of the chain to quantify the rate and direction of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement relative to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a>.<\/p>\n<p>Scientists are divided over how <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> is generated in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a>. Some suggest that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> originate from super-heated material from as deep as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1667\">core<\/a> that reaches the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1658\">crust<\/a> as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1717\">mantle plume<\/a>. Others argue the molten material that feeds <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> is sourced from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>. Of course, it is difficult to collect data from these deep-Earth features due to the extremely high pressure and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1767\">temperature<\/a>.<\/p>\n<p>How <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> are initiated is another highly debated subject. The prevailing mechanism has <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> starting in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1677\">divergent<\/a> boundaries during <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1701\">supercontinent<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1702\">rifting<\/a>. Scientists have identified a number of current and past <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a> believed to have begun this way. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">Subducting<\/a> slabs have also been named as causing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a> plumes and hot-spot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a>. Some geologists have suggested another geological process not involving <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> may be involved, such as a large space objects crashing into Earth. Regardless of how they are formed, dozens are on the Earth. Some well-known examples include the Tahiti Islands, Afar Triangle, Easter Island, Iceland, Galapagos Islands, and Samoan Islands. The United States is home to two of the largest and best-studied <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a>: Hawaii and Yellowstone.<\/p>\n<h3><b>2.7.1 Hawaiian hotspot<\/b><\/h3>\n<figure id=\"attachment_2554\" aria-describedby=\"caption-attachment-2554\" style=\"width: 296px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Hawaii-Emperor_engl.png\"><img class=\"size-medium wp-image-131\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hawaii-Emperor_engl-296x300.png\" alt=\"There are a series of island and seamounts in the Pacific Ocean, with a bend in the middle.\" width=\"296\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2554\" class=\"wp-caption-text\">The Hawaii-Emperor seamount and island chain.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> in Hawaii represent one of the most active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> sites on earth. Scientific evidence indicates the Hawaiian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> is at least 80 million years old. Geologists believe it is actually much older; however any rocks with proof of this have been <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1680\">subducted<\/a> under the ocean floor. The big island of Hawaii sits atop a large <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1717\">mantle plume<\/a> that marks the active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a>. The Kilauea <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcano<\/a> is the main <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_234\">vent<\/a> for this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> and has been actively erupting since 1983.<\/p>\n<p>This enormous <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> island chain, much of which is underwater, stretches across the Pacific for almost 6,000 km. The seamount chain\u2019s most striking feature is a sharp 60-degree bend located at the midpoint, which marks a significant change in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement direction that occurred 50 million years ago. The change in direction has been more often linked to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> reconfiguration, but also to other things like plume migration.<\/p>\n<figure id=\"attachment_2555\" aria-describedby=\"caption-attachment-2555\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Hawaii_hotspot_cross-sectional_diagram.jpg\"><img class=\"size-medium wp-image-132\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hawaii_hotspot_cross-sectional_diagram-300x159.jpg\" alt=\"The islands get older to the left.\" width=\"300\" height=\"159\"><\/a><figcaption id=\"caption-attachment-2555\" class=\"wp-caption-text\">Diagram of the Hawaiian hotspot and islands that it formed.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>In an attempt to map the Hawaiian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1717\">mantle plume<\/a> as far down as the lower <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">mantle<\/a>, scientists have used tomography, a type of three-dimensional seismic imaging. This information\u2014along with other evidence gathered from rock ages, vegetation types, and island size\u2014indicate the oldest islands in the chain are located the furthest away from the active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a>.<\/p>\n<h4><b>2.7.2 Yellowstone hotspot<\/b><\/h4>\n<figure id=\"attachment_2556\" aria-describedby=\"caption-attachment-2556\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/YellowstoneHotspot.jpg\"><img class=\"size-medium wp-image-133\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/YellowstoneHotspot-300x206.jpg\" alt=\"The hotspot started near the Idaho-Oregon-Nevada boarder, then moved toward its present location neat the Wyoming-Idaho-Montana boarder.\" width=\"300\" height=\"206\"><\/a><figcaption id=\"caption-attachment-2556\" class=\"wp-caption-text\">The track of the Yellowstone hotspot, which shows the age of different eruptions in millions of years ago.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Like the Hawaiian version, the Yellowstone <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> is formed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> rising through the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1668\">lithosphere<\/a>. What makes it different is this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> is located under a thick, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>. Hawaii sits on a thin <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">oceanic<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a>, which is easily breached by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> coming to the surface. At Yellowstone, the thick <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> presents a much more difficult barrier for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> to penetrate. When it does emerge, the eruptions are generally much more violent. Thankfully they are also less frequent.<\/p>\n<p>Over 15 million years of eruptions by this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> have carved a curved path across the western United States. It has been suggested the Yellowstone <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> is connected to the much older Columbia River <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_244\">flood basalts<\/a> and even to 70 million-year-old <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanism<\/a> found in the Yukon region of Canada.<\/p>\n<figure id=\"attachment_2557\" aria-describedby=\"caption-attachment-2557\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Yellowstone_volcano_-_ash_beds.jpg\"><img class=\"size-medium wp-image-134\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Yellowstone_volcano_-_ash_beds-300x195.jpg\" alt=\"The eruptions trend eastward due to prevailing winds.\" width=\"300\" height=\"195\"><\/a><figcaption id=\"caption-attachment-2557\" class=\"wp-caption-text\">Several prominent ash beds found in North America, including three Yellowstone eruptions shaded pink (Mesa Falls, Huckleberry Ridge, and Lava Creek), the Bisho Tuff ash bed (brown dashed line), and the modern May 18th, 1980 ash fall (yellow).<\/figcaption><\/figure>\n<p>The most recent major eruption of this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> created the Yellowstone <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_235\">Caldera<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1751\">Lava<\/a> Creek <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1005\">tuff<\/a> formation approximately 631,000 years ago. The eruption threw 1,000 cubic kilometers of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1001\">ash<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1750\">magma<\/a> into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a>, some of which was found as far away as Mississippi. Should the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspot<\/a> erupt again, scientists predict it will be another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_985\">massive<\/a> event. This would be a calamity reaching far beyond the western United States. These super <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> eruptions fill the earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1745\">atmosphere<\/a> with so much gas and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1001\">ash<\/a>, they block sunlight from reaching the earth. Not only would this drastically alter climates and environments around the globe, it could affect worldwide food production.<\/p>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-15\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-15\" class=\"h5p-iframe\" data-content-id=\"15\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"2.6\/7 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3725\" aria-describedby=\"caption-attachment-3725\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/2.6-7-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-135\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/2.6-7-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3725\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for sections 2.6 and 2.7 via this QR Code.<\/figcaption><\/figure>\n<h2><\/h2>\n<h2>Summary<\/h2>\n<figure id=\"attachment_3724\" aria-describedby=\"caption-attachment-3724\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Plate-Tectonics-Basics-YouTube-QR-Code.png\"><img class=\"size-thumbnail wp-image-136\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Plate-Tectonics-Basics-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3724\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">Plate tectonics<\/a> is a unifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a>; it explains nearly all of the major geologic processes on Earth. Since its early inception in the 1950s and 1960s, geologists have been guided by this revolutionary perception of the world. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1733\">theory<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1654\">plate tectonics<\/a> states the surface layer of the Earth is broken into a network of solid, relatively <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1661\">brittle<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a>. Underneath the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> is a much hotter and more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1660\">ductile<\/a> layer that contains zones of convective upwelling generated by the interior heat of Earth. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1655\">convection<\/a> currents move the surface <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> around\u2014bringing them together, pulling them apart, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_494\">shearing<\/a> them side-by-side. Earthquakes and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanoes<\/a> form at the boundaries where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plates<\/a> interact, with the exception of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_228\">volcanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1716\">hotspots<\/a>, which are not caused by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1669\">plate<\/a> movement.<\/p>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-16\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-16\" class=\"h5p-iframe\" data-content-id=\"16\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 2 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3723\" aria-describedby=\"caption-attachment-3723\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ch.2-Review-QR-Code.png\"><img class=\"size-thumbnail wp-image-137\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.2-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3723\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 2 via this QR Code.<\/figcaption><\/figure>\n<h2>References<\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n<li class=\"csl-entry\">Aitta, A., 2006, Iron melting curve with a tricritical point: J. 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Ein Beitrag zur Geschichte der Geologie in \u00d6sterreich: Mitt. Oesterr. Geol. Ges., v. 73, p. 237\u2013254.<\/li>\n<li class=\"csl-entry\">Forsyth, D.W., 1975, The Early Structural Evolution and Anisotropy of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1659\">Oceanic<\/a> Upper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1664\">Mantle<\/a>: Geophys. J. Int., v. 43, no. 1, p. 103\u2013162., doi: <a href=\"https:\/\/doi.org\/10.1111\/j.1365-246X.1975.tb00630.x\">10.1111\/j.1365-246X.1975.tb00630.x<\/a>.<\/li>\n<li class=\"csl-entry\">Frankel, H., 1982, The Development, Reception, and Acceptance of the Vine-Matthews-Morley <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_461_1730\">Hypothesis<\/a>: Hist. Stud. Phys. Biol. 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Forms commonly in dunes, larger in eolian dunes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2027\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2027\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1660\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1660\"><div tabindex=\"-1\"><p>A vast stretch of sand dunes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2028\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2028\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2190\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2190\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_968\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_968\"><div tabindex=\"-1\"><p>By Matt Affolter(QFL247) (talk) (Transferred by Citypeek\/Original uploaded by Matt Affolter(QFL247)) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a> or <a href=\"http:\/\/www.gnu.org\/copyleft\/fdl.html\">GFDL<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AHanksite.JPG\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_494\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_494\"><div tabindex=\"-1\"><p>Rob Lavinsky, <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/www.irocks.com\/\">iRocks.com<\/a> \u2013 CC-BY-SA-3.0 [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AApatite-(CaF)-280343.jpg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2029\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2029\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1254\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1254\"><div tabindex=\"-1\"><p>Chemical sedimentary rocks that have a biologic component to their origin. Many limestones are biochemical.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_482\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_482\"><div tabindex=\"-1\"><p>By Sbyrnes321 (Own work) [Public domain], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AHalflife-sim.gif\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2030\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2030\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_495\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_495\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_1938\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_1938\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2440\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2440\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_995\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_995\"><div tabindex=\"-1\"><p>A solid part&nbsp;of the lithosphere which moves as a unit, i.e. the entire plate generally moves the same direction at the same speed.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2036\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2036\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_990\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_990\"><div tabindex=\"-1\"><p>Middle chemical layer of the Earth, made of mainly iron and magnesium silicates. It is generally denser than the crust (except for older oceanic crust) and less dense than the core.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_461_2213\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_461_2213\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":291,"menu_order":6,"template":"","meta":{"pb_show_title":"","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[49],"contributor":[],"license":[],"class_list":["post-461","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":19,"_links":{"self":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/461","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/users\/291"}],"version-history":[{"count":2,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/461\/revisions"}],"predecessor-version":[{"id":1795,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/461\/revisions\/1795"}],"part":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/parts\/19"}],"metadata":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/461\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/media?parent=461"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapter-type?post=461"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/contributor?post=461"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/license?post=461"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}