mineral

Mica

Muscovite / Biotite (Phyllosilicate group)

Mohs hardness: 2-2.5; Color: Clear, silvery, brownish, or dark green; Luster: Vitreous to pearly; Crystal structure: Monoclinic, forms in distinct tabular crystals and books with perfect basal cleavage allowing it to split into extremely thin, flexible sheets; Specific gravity: 2.7-3.1

Hardness: 2-2
Color: Clear, silvery, brownish, or dark green
Luster: Vitreous to pearly

Identified July 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous environments (such as granites and pegmatites) as well as metamorphic rocks (like schists and gneisses) through crystallization from cooling magma or regional metamorphism of argillaceous sediments.

Uses & applications

Used in electrical insulators, drywall joint compound, cosmetics for shimmer, paints, lubricants, and electronics due to its thermal and electrical insulating properties.

Geological facts

Mica sheets were historically used as windows in stoves and lanterns before modern glass, and the name comes from the Latin word 'micare', meaning to shine or glitter.

Field identification & locations

Easily identified in the field by its distinct sheet-like structure and extreme platy cleavage, which allows it to be peeled into flexible, transparent layers. Common worldwide in pegmatite veins and metamorphic terranes.