Mineral

Muscovite (White Mica)

Muscovite - Potassium aluminum silicate: KAl2(AlSi3O10)(F,OH)2

Hardness: 2.5 on Mohs scale; Color: Colorless, silvery, or pale yellowish-green; Luster: Pearly to Vitreous; Crystal system: Monoclinic; Cleavage: Perfect basal (peels into thin, flexible sheets).

Hardness: 2
Color: Colorless, silvery, or pale yellowish-green
Luster: Pearly to Vitreous

Identified March 17, 2026More mineral →

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Physical properties

Hardness: 2.5 on Mohs scale; Color: Colorless, silvery, or pale yellowish-green; Luster: Pearly to Vitreous; Crystal system: Monoclinic; Cleavage: Perfect basal (peels into thin, flexible sheets).

Formation & geological history

Forms primarily in metamorphic rocks like schist and gneiss, as well as in igneous rocks like granite pegmatites. It can occur across all geological ages, often forming from the alteration of feldspars.

Uses & applications

Used as an electrical insulator in electronics, as a glitter effect in cosmetics and paint, in joint compounds, and as a heat-resistant window material (Isinglass) for wood stoves.

Geological facts

In the past, large sheets of muscovite were used for windows in Russia and were known as 'Muscovy glass,' which is where the mineral gets its name. It is highly heat resistant and does not conduct electricity.

Field identification & locations

Identify by its 'book' like appearance—sheets that can be peeled away with a fingernail. It is found globally, with major deposits in India, Brazil, and the USA (North Carolina and South Dakota).

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