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19 Cards in this Set
- Front
- Back
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Felsic Minerals |
Light Colored because they lack Iron and Magnesium. |
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Mafic Minerals |
Have Magnesium and Iron. Dark because of Iron and magnesium |
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Chemical Composition 4 Groups |
Felsic (Acidic) Compositional Group
Mafic (Basic) compositional group
Ultramafic (UltraBasic) Compositional group
Intermediate compostion group |
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Felsic (acidic) Compositional Group |
THe name felsic refers to feldspars (Far-) and other silica-rich (-sic) minerals but it is now also used (in place of "acidic") to describe magmas, lavas, and igneous rocks containing more than 60% silica |
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Mafic (basic) Compositional group |
Mafic refers to the minerals with Magnesium (ma-) and iron (-fic) in their chemical formulas, but now refers to magmas and lavas and igneous rocks contained 45%-53% Silica |
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Ultramafic (Ultrabasic) Compositional group |
As the name implies, this term was orginally used to describe igneous rocsk made almost entirely of mafic minerals. However it now also is used (in place of Ultrabasic) to describe Magmas, lavas, and igneous rocks containing less than 40% Silica |
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Intermediate Compositional groups |
Magmas, lavas and ignous rocks that contain 54-64% silica. A compositon between mafic and felsic. |
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Physical Composition |
Volcanic Glass Mineral grains (Crystals) Pyroclasts Xenoliths |
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Volcanic Glass |
No definite form Called obsidian Transparent or translucent when held up to a light. Associated wtih felic rocks because high percentage of silica that can polymerize rather than mineral crystals Can be Red-Brown, black, gray or tan. Darker color comes from oxidation and irons. A little bit of magnetite or hematite to darken the glass
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Mineral grains (Crystals) |
Most igneous rocks, even pieces of volcanic glass, contain some proportion of mineral crystals- either mafic (dark colored ferromagnesian minerals) |
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Mafic |
Iron and Magnesium Black, brown, blood red |
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Felsic |
Has Silica and Potassium Fieldspar Light Colored White, Light Gray, and Pastels |
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Intermediate |
Mixture of Mafic and Felsic Minerals Medium Colors |
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Igneous Composition |
Mafic |
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Pegmatitic |
Crystals caused by inrusive cooling that are 1 CM or greater |
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Glassy |
Caused by Extrusive cooling |
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Phaneritic |
Crystals caused by intrusive cooling |
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Igneous Texture |
Intrusive Cooling Phaneretic, Pegmatitic
porphyritic texture
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Prophytrite Texture |
Create by 2 different stages of cooling. |
