Rock Identifier
Muscovite Mica (Muscovite (KAl2(AlSi3O10)(OH)2)) — mineral
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
Identified More mineral

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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.