mineral

Muscovite mica (mica crystal)

Muscovite, KAl₂(AlSi₃O₁₀)(OH)₂

AI-generated identification · may be incorrect

Transparent to smoky-brown, glassy/pearly luster, sheet-like crystal structure, and perfect basal cleavage; separates into flexible elastic flakes. Mohs hardness 2–2.5 and specific gravity about 2.8–2.9.

Identified August 21, 2026More mineral →

Explore Muscovite mica (mica crystal) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms mainly in granitic pegmatites, granites, and metamorphic schists during slow cooling or high-temperature metamorphism. It is a common Precambrian and younger mineral, including in East African crystalline basement rocks.

Uses & applications

Used industrially as electrical and thermal insulation, fillers, paints, joint compounds, and cosmetics; attractive transparent plates are collected but usually have modest value.

Geological facts

The specimen appears to be a large cleavage fragment rather than a complete crystal. Its sheet-like transparency and reflective cleavage strongly distinguish mica from glass.

Field identification & locations

Identify by peeling into thin, flexible sheets that remain elastic and by its low hardness; a fingernail may scratch its surface. The reported Tanzanian locality is geologically plausible, especially in granitic or metamorphic terrain, though exact identification would benefit from testing for elasticity and composition.