mineral

Muscovite Mica

Muscovite - KAl2(AlSi3O10)(OH)2

Hardness: 2-2.5 on Mohs scale; Color: Colorless, silvery, or light brown; Luster: Pearly to Vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76-3.0

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

Identified June 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed in regional metamorphic rocks such as schists and gneisses, as well as in felsic igneous rocks like granites and pegmatites. It forms through the crystallization of magma or the metamorphism of clay-rich sediments.

Uses & applications

Used as an electrical and thermal insulator in electronics, as a filler in paints and plastics, and in cosmetics (eye shadow and nail polish) to add 'shimmer'. Historically used for oven windows.

Geological facts

Also known as 'common mica' or 'potash mica'. Its name comes from 'Muscovy-glass', as large sheets were used for windows in Russia before glass became cheap and accessible.

Field identification & locations

Identify by its ability to peel into thin, flexible, transparent sheets using a fingernail or pocketknife. Commonly found in micaceous schists and granite pegmatites globally.