metamorphic

Biotite Schist

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

AI-generated identification · may be incorrect

Hardness: 2.5-3 (on mica flakes), Color: dark brown to black, Luster: vitreous to pearly, Crystal structure: monoclinic (tabular/platy), Cleavage: perfect basal cleavage

Hardness: 2

Identified May 23, 2026More metamorphic →

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Physical properties

Hardness: 2.5-3 (on mica flakes), Color: dark brown to black, Luster: vitreous to pearly, Crystal structure: monoclinic (tabular/platy), Cleavage: perfect basal cleavage

Formation & geological history

Formed through the regional metamorphism of shale or mudstone under medium-grade temperatures and pressures. Often associated with the formation of mountain ranges during orogenic events.

Uses & applications

Used primarily for research, as an indicator mineral for metamorphic grade, and occasionally as a ground-up additive in paints, lubricants, and rubber products.

Geological facts

Biotite belongs to the mica group; it is often called 'black mica'. Its presence in schist creates a sparkling effect when light reflects off the aligned mineral grains.

Field identification & locations

Identify by its 'schistose' texture (mineral alignment) and the ability to peel off thin, dark, flexible flakes from the black mineral sections with a needle.