metamorphic

Biotite Schist

Biotite-rich Schist

AI-generated identification · may be incorrect

Hardness: 2.5–3 (for biotite flakes); Color: Black, dark brown, or dark grey; Luster: Pearly to vitreous (often sparkly or shiny due to mica); Structure: Foliated with visible mica alignment; Cleavage: Perfect basal cleavage in individual flakes.

Hardness: 2
Color: Black, dark brown, or dark grey
Luster: Pearly to vitreous (often sparkly or shiny due to mica)

Identified July 21, 2026More metamorphic →

Explore Biotite Schist 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

Formed through the regional metamorphism of clay-rich sedimentary rocks like shale or igneous rocks at medium grades of pressure and temperature (greenschist to amphibolite facies).

Uses & applications

Used primarily as decorative stone, in geological education, and occasionally as a filler in construction materials if found in large quarry quantities.

Geological facts

The 'sparkly' appearance is caused by the alignment of thin, sheet-like mica minerals. It is part of a metamorphic sequence that progresses from slate to phyllite, then schist, and finally gneiss.

Field identification & locations

Identify by its 'schistosity' or layering and the prominent shiny black flakes that can often be peeled off with a knife. Common in mountainous regions with a history of plate collisions.