mineral

Muscovite Mica (in Quartz/Feldspar Matrix)

Muscovite - KAl2(AlSi3O10)(OH)2

AI-generated identification · may be incorrect

Hardness: 2.5–3 on Mohs scale; Color: Silvery-white to pale brown (shown in specimen); Luster: Pearly to metallic; Crystal structure: Monoclinic (distinctly sheet-like/foliated); Cleavage: Perfect basal cleavage, meaning it peels into thin, flexible sheets; Specific Gravity: 2.76–3.00.

Hardness: 2
Color: Silvery-white to pale brown (shown in specimen)
Luster: Pearly to metallic

Identified March 31, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous pegmatites and metamorphic rocks (schists and gneishes) through the cooling of silica-rich magma or the transformation of clay minerals under high pressure and temperature. Found in geological formations ranging from Precambrian to Cenozoic eras.

Uses & applications

Used primarily as an electrical insulator in electronics and vacuum tubes due to high heat resistance. Ground mica is used in joint compounds, automotive paints (for pearlescent finish), cosmetics (glimmer/shimmer in eyeshadow), and as drilling mud in the oil industry.

Geological facts

Muscovite was historically used as a glass substitute for windows in Russia, hence the name 'Muscovy-glass.' Large sheets of it are flexible and can be bent without breaking, returning to their original shape.

Field identification & locations

Identify in the field by its 'metallic' luster that reflects sunlight and its ability to be easily scratched or peeled into thin flakes with a fingernail or knife. Commonly found in granitic environments globally, especially in Brazil, India, and the Appalachian mountains in the US.