mineral

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Hardness: 2.0–2.5 Mohs. Color: Colorless, silvery, or golden-brown due to impurities. Luster: Pearly to metallic. Crystal structure: Monoclinic; exhibits perfect basal cleavage allowing it to be split into thin, flexible, elastic sheets.

Hardness: 2
Color: Colorless, silvery, or golden-brown due to impurities
Luster: Pearly to metallic

Identified July 1, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in igneous rocks like granites and pegmatites, and in metamorphic rocks such as schists and gneisses. It forms through the crystallization of magma or the metamorphism of clay-rich sedimentary rocks.

Uses & applications

Used as an electrical insulator in electronics, in joint compound, as a lubricant, and in cosmetics (pigments and glitter). Historically used as a heat-resistant window material (Muscovy-glass).

Geological facts

Muscovite was once used for windows in Russia because it is transparent and heat-resistant, leading to the name 'Muscovy-glass'. It is highly resistant to heat and electricity.

Field identification & locations

Identified by its shiny, flaky appearance and the ability to peel layers off with a fingernail. It is common in sparkling sands and rocky outcrops of granite.