mineral

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Hardness: 2-2.5; Color: Colorless, silvery-white, or light gray; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific gravity: 2.76–3.0

Hardness: 2-2
Color: Colorless, silvery-white, or light gray
Luster: Vitreous to pearly

Identified April 6, 2026More mineral →

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Physical properties

Formation & geological history

Commonly formed in igneous rocks like granites and pegmatites, and in metamorphic rocks like schists and gneisses through regional metamorphism. It forms under a wide range of temperatures and pressures.

Uses & applications

Used as an electrical and thermal insulator in electronics, as a filler in paints and plastics, in joint compounds for drywall, and as 'glitter' in cosmetics like eyeshadow and nail polish.

Geological facts

In medieval Russia, large sheets of muscovite were used for windows as a cheaper alternative to glass, which is why it was historically called 'Muscovy-glass'. Due to its heat resistance, it was also used for wood-stove windows.

Field identification & locations

Identify in the field by its distinct ability to peel into thin, flexible, transparent sheets and its pearly, reflective luster. It is ubiquitous in crushed granite gravel and mountain outcrops.