mineral

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Hardness: 2.0–2.5 (Mohs scale); Color: Colorless, silvery-white, or light gray; Luster: Pearly to vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin, flexible sheets); Specific Gravity: 2.76–3.00

Hardness: 2
Color: Colorless, silvery-white, or light gray
Luster: Pearly to vitreous

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous environments (granites and pegmatites) and metamorphic rocks (schists and gneisses) under high pressure and temperature. It is a common rock-forming mineral found in all geological ages.

Uses & applications

Used as an electrical insulator in capacitors and heating elements due to its high thermal stability. Also used in cosmetics (glitter/shimmer), fillers in paint, plastics, and as high-temperature windows for furnaces.

Geological facts

Also known as 'Muscovy glass' because it was used in medieval Russia as a glass substitute for windows. It can be found in massive sheets called 'books' that can be over a meter wide.

Field identification & locations

Identify in the field by its distinct ability to peel into thin, transparent, flexible layers. Commonly found in coarse-grained granite or sparkled across the surface of metamorphic schists. Often found in South Dakota (USA), Brazil, and India.