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Name: |
mica : Muscovite, Biotite, Phlogopite, Lepidolite |
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Class: |
Silicates |
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Chemistry: |
K2Al2((AlSi3O10)|(OH,F)2 ) Muscovite (fuchsite) K(Mg,Fe)3((AlSi3O10)|(OH,F)2) Biotite KMg3( (AlSi3O10)|(OH,F)2 ) Phlogopite KLi2Al( (AlSi3O10)|(OH,F)2 ) Lepidolite Mixed hydrated potassium aluminum silicates with a sheet structure. |
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Color(s): |
Muscovite: colorless, yellow, silvery, green (fuchsite), Biotite: black, brown, bronze, Phlogopite: reddish-brown, brown, black, yellowish, Lepidolite: purple, magenta, pink, gray |
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Hardness: |
2 -3.5 |
SpecGrav: |
2.7 - 3.8 |
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Fracture: |
foliated |
Cleavage: |
perfect |
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Crystal: |
monoclinic (tabular habit, with thin parallel growths, can easily be separated into thin layers.) |
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Envronment: |
common rock forming minerals (all except lepidolite), and can be found in metamorphic rocks, pegmatites, and veins. |
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Association: |
quartz, calcite, spinel, garnet, feldspars, andalusite,albite |
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Locals: |
| USSR | India | Italy | South Africa | Canada | Scotland | Germany | Austria | Finland | Switzerland | Colorado, Utah, S.D., N.H., Calif., Idaho, Maine, USA | |
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Misc: |
Muscovite: comes from the local Muscovy (Russia) where in ancient times it was used as glass in buildings. Biotite: is named after J.B. Biot, a French astronomer, physicist and mathematician. Phlogopite: comes from the Greek "phlogopos", meaning "firey-look" from its reddish-brown color. Lepidolite: comes from the Greek "lepidos", meaning "scale", alluding to the scaly conglomerates in which it often forms . Phlogopite and Biotite both dissolve in sulfuric acid. Lepidolite give a RED flame test. Fuchsite: is a variety of muscovite that contains traces of chromium and is colored green. There have been some large finds in Minas Gerais, Brazil, but much of it is miss-labeled as "Fuschite". |
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