Mineral (Found in Igneous and Metamorphic rocks)
Mica (specimen appears to be Muscovite or Phlogopite)
Phyllosilicate mineral; Muscovite: KAl2(AlSi3O10)(F,OH)2
Hardness: 2-2.5 (Mohs scale); Color: Silvery-white to brownish-gold; Luster: Pearly to Vitreous; Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76-3.0
- Hardness
- 2-2
- Color
- Silvery-white to brownish-gold
- Luster
- Pearly to Vitreous
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Physical properties
Hardness: 2-2.5 (Mohs scale); Color: Silvery-white to brownish-gold; Luster: Pearly to Vitreous; Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76-3.0
Formation & geological history
Formed through the regional metamorphism of argillaceous rocks or as a primary mineral in felsic igneous rocks (granites/pegmatites). It can be found in rocks from the Precambrian to Cenozoic eras.
Uses & applications
Used primarily as an electrical insulator in electronics, as a filler in paints and plastics, and in cosmetics (glitter effect). Historically used for furnace windows ('Isinglass').
Geological facts
Mica is one of the few minerals that can be split into sheets thin enough to be transparent while remaining heat resistant. It was once used as window panes for homes in Russia before glass became common.
Field identification & locations
Identify by its 'peeling' nature; specimens split easily into thin, flexible, elastic flakes. Commonly found in pegmatite veins or schist. High-quality specimens are often found in Brazil, India, and the USA (Appalachians).
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