mineral

Muscovite Mica

KAl2(AlSi3O10)(F,OH)2

Hardness: 2-2.5 on Mohs scale; Color: Colorless, silvery, or light brown; Luster: Pearly to vitreous; Crystal system: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76-3.00

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

Identified May 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous environments (granites and pegmatites) and metamorphic rocks (schists and gneisses). It is a phyllosilicate mineral that crystallizes from silica-rich melts or through the metamorphism of clay-rich sediments.

Uses & applications

Used in electrical insulation, high-temperature furnace windows (isinglass), joint compound for drywall, plastics, rubber, and as a pearlescent pigment in cosmetics like eye shadow and nail polish.

Geological facts

Historically known as 'Muscovy glass' because it was used in Russia for window panes before glass was widely available. It is heat resistant and doesn't conduct electricity, making it vital for early electronics.

Field identification & locations

Identify in the field by its distinct 'book-like' layered structure and the ability to peel off elastic, transparent thin sheets with a fingernail. Commonly found in coarse-grained igneous rocks.