Rock Identifier
Muscovite Mica (with Quartz) (Muscovite (KAl2(AlSi3O10)(OH)2)) — mineral
mineral

Muscovite Mica (with Quartz)

Muscovite (KAl2(AlSi3O10)(OH)2)

Hardness: 2.0-2.5; Color: Silvery-green to pale bronze; Luster: Pearly to metallic; Crystal structure: Monoclinic; Cleavage: Perfect basal cleavage (peels in thin sheets); Specific gravity: 2.8

Hardness
2
Color
Silvery-green to pale bronze
Luster
Pearly to metallic
Identified More mineral

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Physical properties

Hardness: 2.0-2.5; Color: Silvery-green to pale bronze; Luster: Pearly to metallic; Crystal structure: Monoclinic; Cleavage: Perfect basal cleavage (peels in thin sheets); Specific gravity: 2.8

Formation & geological history

Formed primarily in igneous rocks like granite pegmatites and metamorphic rocks like schists and gneisses. This specimen appears to be from a pegmatite, where large crystals grow slowly from water-rich magma.

Uses & applications

Used as an electrical insulator in electronics, in joint compound for drywall, as a filler in plastics and paint, and in cosmetics (shimmer/glitter). Minor use as a collector specimen.

Geological facts

Muscovite was once known as 'Muscovy glass' because it was used in Russia for windows before glass became affordable. Its sheets are highly heat-resistant and non-conductive.

Field identification & locations

Identify in the field by its distinct ability to be peeled into thin, flexible, transparent flakes with a fingernail. Commonly found in granitic outcrops or riverbeds near metamorphic terrain.