
mineral
Muscovite Mica
Muscovite (KAl2(AlSi3O10)(OH)2)
Hardness: 2.5 on Mohs scale; Color: Colorless, silvery, or brownish in thick books; Luster: Pearly to Vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin flexible sheets); Specific Gravity: 2.8
- Hardness
- 2
- Color
- Colorless, silvery, or brownish in thick books
- Luster
- Pearly to Vitreous
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Physical properties
Hardness: 2.5 on Mohs scale; Color: Colorless, silvery, or brownish in thick books; Luster: Pearly to Vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin flexible sheets); Specific Gravity: 2.8
Formation & geological history
Forms in igneous rocks like pegmatites or granites, and in metamorphic rocks like schists and gneisses during regional metamorphism.
Uses & applications
Used as an electrical insulator in electronics, in joint compound for drywall, as a filler in paint and plastics, and in cosmetics (glitter/shimmer).
Geological facts
The name 'Muscovite' comes from 'Muscovy-glass', as the mineral was used in transparent window panes in medieval Russia as a cheaper alternative to glass.
Field identification & locations
Identified by its ability to split into paper-thin, transparent, flexible sheets. Commonly found in granitic pegmatites. Collectors look for large 'books' or thick clusters.
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