mineral

Muscovite Mica (on Quartz Matrix)

Muscovite - KAl2(AlSi3O10)(OH)2

Hardness: 2.5–3 on Mohs scale; Color: Silvery-white to colorless; Luster: Vitreous to pearly; Crystal structure: Monoclinic (forming tabulare sheets); Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76–3.00

Hardness: 2
Color: Silvery-white to colorless
Luster: Vitreous to pearly

Identified March 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous environments (granitic pegmatites) and metamorphic rocks (schists and gneisses). Generally associated with high-silica geological events ranging from the Precambrian to more recent eras.

Uses & applications

Used as an electrical and thermal insulator in electronics, as a lubricant, in the manufacture of drywall joint compound, and as a pearlescent pigment in cosmetics like glitter and eyeshadow.

Geological facts

Also known as 'Muscovy glass' because it was used in medieval Russia as a cheaper, more durable alternative to glass for windows. It can withstand extreme temperatures without melting or breaking.

Field identification & locations

Identify in the field by its 'books' of thin, flexible, elastic sheets that can be peeled with a fingernail. Commonly found in Brazil, India, and the United States (Appalachian range and Black Hills).

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