Physical Features
1. Color- Colorless to pale yellow.
2. Streak- White.
3. Luster- Pearly.
4. Cleavage- Perfect.
5. Transparency- Transparent in thin layers.
6. Fracture- Even.
7. Hardness- 2 to 4.
8. Forms- Poorly crystalized.
There are 37 different mica minerals, all in which have crystalline structure that forms layers that can be split into thin sheets. Chemically they contain complex silicates of aluminium and alkalies with hydroxyl. Some varieties may contain iron, magnesium, and lithium. Mica can be found in pegmatites which are widely distributed and occurs in igneous, metamorphic and sedimentary rocks (granite). Mica pegmatite consists of a quartz core with feldspar sides. There are seven important mica minerals. Starting with the most popular of the group. 1. Muscovite, 2. Paragonite, 3. Lepidolite, 4. Phlogopite, 5. Biotite, 6. Zinnualdite, 7. Lepidomelane. Mica occurs all over the world.
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