mineral

Mica

Phyllosilicate (group name), typically Muscovite KAl2(AlSi3O10)(OH)2 or Biotite K(Mg,Fe)3(AlSi3O10)(OH)2

Hardness: 2.0–4.0; Color: Silvery-gray, brownish, or black; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific gravity: 2.7–3.1

Hardness: 2
Color: Silvery-gray, brownish, or black
Luster: Vitreous to pearly

Identified May 25, 2026More mineral →

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Physical properties

Hardness: 2.0–4.0; Color: Silvery-gray, brownish, or black; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific gravity: 2.7–3.1

Formation & geological history

Formed in igneous environments (granites, pegmatites) and metamorphic rocks (schists, gneisses) through cooling of magma or under high pressure and temperature conditions.

Uses & applications

Used as an electrical insulator in electronics, as a filler in paints and plastics, in joint compounds for drywall, and in cosmetics for its pearlescent shimmer.

Geological facts

Mica is famous for its 'books' or stacks of sheets that can be peeled away. During World War II, mica was considered a strategic material due to its heat resistance and electrical insulation properties.

Field identification & locations

Identify in the field by its distinct flaky texture and shiny, metallic luster. It can be easily scratched with a fingernail and splits into flexible, elastic layers. Commonly found in sparkling river sands or embedded in crystalline rocks.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral