mineral

Muscovite (Mica)

Muscovite - KAl2(AlSi3O10)(OH)2

Hardness: 2-2.5 on Mohs scale; Color: Colorless, silvery-white, or light brown; Luster: Pearly to vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76-3.00

Hardness: 2-2
Color: Colorless, silvery-white, or light brown
Luster: Pearly to vitreous

Identified June 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous rocks like granites and pegmatites, as well as metamorphic rocks like schists and gneisses. It forms from the cooling of silica-rich magma or the metamorphism of clay-rich sediments.

Uses & applications

Used as an electrical insulator in electronic equipment, as a filler in paints and plastics, in joint compounds for drywall, and in cosmetics (shimmer/glitter). Fine specimens are kept by collectors.

Geological facts

Muscovite was once used as a glass substitute for windows in Russia, leading to the name 'Muscovy glass.' Because it is a poor conductor of heat and electricity, it was historically vital for wood stoves and early electrical systems.

Field identification & locations

Identified in the field by its distinct 'book-like' appearance and the ability to peel off flexible, transparent sheets with a fingernail. Commonly found globally in granitic pegmatite deposits.