Mineral

Muscovite (Mica)

Muscovite - KAl2(AlSi3O10)(OH)2

Hardness: 2.5–3 on Mohs scale; Color: Colorless, silvery-white, or light green; Luster: Pearly to Vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin, flexible sheets); Specific Gravity: 2.76–3.0

Hardness: 2
Color: Colorless, silvery-white, or light green
Luster: Pearly to Vitreous

Identified March 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous rocks like pegmatites and granites, or in metamorphic rocks such as schists and gneisses. It forms from the cooling of magma or the metamorphism of clay-rich sediments over millions of years.

Uses & applications

Used as an electrical insulator in electronics, a filler in paints and plastics, a pearlescent agent in cosmetics (foundation and eyeshadow), and in historical 'Muscovy glass' for windows.

Geological facts

Muscovite was once used for window panes in Russia because it is heat resistant and transparent; this is why it is named after the province of Muscovy. The sheets are so flexible they can be bent and will pop back into shape.

Field identification & locations

Identify in the field by its distinct 'book-like' layers that can be peeled apart with a fingernail and its reflective, glittery appearance. Common in mountainous regions with metamorphic outcrops.