Rock Identifier
Mica (Muscovite) in Granite (Muscovite (KAl2(AlSi3O10)(OH)2)) — mineral
mineral

Mica (Muscovite) in Granite

Muscovite (KAl2(AlSi3O10)(OH)2)

Hardness: 2.0-2.5 on Mohs scale; Color: Silver, white, or colorless; Luster: Pearly to metallic; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets)

Hardness
2
Color
Silver, white, or colorless
Luster
Pearly to metallic
Identified More mineral
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Physical properties

Hardness: 2.0-2.5 on Mohs scale; Color: Silver, white, or colorless; Luster: Pearly to metallic; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets)

Formation & geological history

Forms in igneous rocks like granite and pegmatites through the cooling of silica-rich magma, or in metamorphic rocks like schist through high-pressure alteration of clay minerals.

Uses & applications

Used as an electrical insulator in electronics, as a filler in paint and plastic, and in cosmetics (glitter/shimmer).

Geological facts

The name 'Muscovite' comes from 'Muscovy-glass', as large sheets of it were used for windows in medieval Russia because it is transparent and heat-resistant.

Field identification & locations

Identified by its shiny, reflective flakes and its ability to be peeled into thin, flexible, transparent layers with a fingernail. Found globally in granitic terrains.