mineral

Muscovite Mica

Muscovite - KAl2(AlSi3O10)(F,OH)2

Hardness: 2-2.5 on Mohs scale. Color: Pearly silver, light brownish-gray, transparent to translucent. Luster: Pearly to vitreous. Crystal system: Monoclinic. Cleavage: Perfect basal cleavage, peeling into thin, flexible, elastic sheets. Specific gravity: 2.77-2.88.

Hardness: 2-2
Luster: Pearly to vitreous

Identified July 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in intrusive igneous rocks such as granites and pegmatites, as well as in regional metamorphic rocks like mica schists and gneisses.

Uses & applications

Used as an electrical insulator in electronics, thermal insulation, pearlescent pigment in cosmetics and paints, joint compound additive, and as educational mineral specimens.

Geological facts

Historically, thick sheets of muscovite were used as window glass in Russia, which gave rise to its name derived from 'Muscovy glass'. Sheets can be split extraordinarily thin down to sub-micron thickness.

Field identification & locations

Identified by its distinctive ability to peel into thin, silvery, flexible sheets (basal cleavage). Commonly found in pegmatite deposits worldwide including India, Brazil, Russia, and the United States (North Carolina, Maine).