mineral

Muscovite Mica

Muscovite [KAl2(AlSi3O10)(OH)2]

Hardness: 2.5 on Mohs scale; Color: Colorless, silvery, or light yellow/green; Luster: Pearly to metallic; Crystal Structure: Monoclinic; Cleavage: Perfect basal cleavage producing thin, flexible sheets.

Hardness: 2
Color: Colorless, silvery, or light yellow/green
Luster: Pearly to metallic

Identified July 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in igneous rocks like granites and pegmatites, as well as metamorphic rocks like schists and gneisses through regional metamorphism.

Uses & applications

Used as an electrical insulator in capacitors, a heat insulator in furnace windows (Isinglass), a filler in paints and plastics, and as a glitter effect in cosmetics like lip gloss and eyeshadow.

Geological facts

Historically, large sheets of muscovite were used for windows in Russia, leading to the name 'Muscovy Glass'. It can withstand temperatures up to 700 degrees Celsius without melting or losing its properties.

Field identification & locations

Identified in the field by its distinct ability to be peeled into thin, transparent, flexible sheets. Commonly found in coarse-grained pegmatites and schistose metamorphic rocks worldwide.