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Native elements |
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GRAPHITE |
C |
1)
metamorphic settings such as schist, marble, gneiss, 2) rarely in felsic
igneous rocks |
quartz,
feldspar, calcite, micas |
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Oxides |
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corundum |
Al2O3 |
Accessory
mineral in quartz-free 1) metamorphosed carbonates, 2) detrital in
sediments (placers), 3) Al-rich igneous rocks, 4) carbonate skarns |
carbonates, feldspathoids, magnetite, hematite.
Anti-association: quartz |
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Blue
corundum is sapphire, red is ruby. |
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spinel (spihn-elle') |
MgAl2O4 |
1)
in high temperature metamorphosed carbonates or schists, 2) accessory in
mafic igneous rocks, 3) placers |
Calcite,
dolomite, garnet, and Ca-Mg silicates in marble; garnet, corundum,
sillimanite, andalusite, and cordierite in aluminous rocks; diopside,
olivine, and chondrodite in mafic igneous rocks; other dense minerals in
placers. Anti-association for Mg-rich
spinel: quartz |
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Nesosilicates |
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andalusite |
Al2SiO5 |
1) low pressure metamorphic pelitic rocks |
cordierite, sillimanite, kyanite, garnet, micas,
quartz |
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sillimanite (sill'-uh-mun-ight) |
Al2SiO5 |
1) high temperature metamorphic pelitic rocks |
garnet, cordierite, spinel, hypersthene,
orthoclase, biotite, quartz |
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kyanite |
Al2SiO5 |
1) medium to high-pressure schists and gneisses |
quartz, feldspar, mica, garnet, corundum,
staurolite |
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staurolite |
hydrous Al, Fe, Mg nesosilicate |
1) medium to high grade metamorphic rocks |
kyanite, garnet, chloritoid, micas, tourmaline |
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ALMANDINE |
Fe3Al2Si3O12 |
1) medium to high grade metamorphic rocks |
quartz, feldspar, micas, staurolite, cordierite,
chloritoid, tourmaline, and kyanite or sillimanite |
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Cyclosilicates |
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cordierite |
hydrous Al, Mg cyclosilicate |
1) high-grade contact or regional metamorphism of
aluminous rocks |
garnet, sillimanite, spinel, plagioclase,
anthophyllite, orthopyroxene |
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Inosilicates--amphiboles
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cummingtonite |
Mg7Si8O22(OH)2 |
1) medium-grade metamorphic rocks |
other amphiboles, garnet, plagioclase, cordierite |
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Grunerite is the Fe end member, present in
metamorphosed Fe-rich rocks, with magnetite, hematite, minnesotaite,
hedenbergite, fayalite, and garnet. |
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tremolite-ACTINOLITE |
Ca2(Mg,
Fe)5Si8O22(OH)2 |
1) low grade metamorphosed carbonates, 2)
medium-grade metamorphosed mafic rocks |
calcite, dolomite, talc, quartz, forsterite,
diopside, phlogopite; albite, epidote, chlorite, quartz |
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Tremolite is the Mg end member; actinolite has
more Fe and is more common. Ferroactinolite is the Fe end member. |
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