metamorphic

Biotite-rich schist (likely mica schist)

Mica schist; predominantly biotite mica with quartz and feldspar

AI-generated identification · may be incorrect

Typically medium-grained, flaky, and strongly foliated, with dark brown-black mica and lighter quartz/feldspar; mica has Mohs hardness 2.5–3, while quartz is 7. Luster is commonly pearly to vitreous, with platy cleavage and moderate density around 2.7–3.0.

Identified August 19, 2026More metamorphic →

Explore Biotite-rich schist (likely mica 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 when shale or other clay-rich sediment is subjected to regional metamorphism, causing mica growth and alignment; commonly Paleozoic to Precambrian, though age depends on locality.

Uses & applications

Used mainly as a decorative or educational specimen; too foliated for most structural construction, though related schists may be used as dimension stone or aggregate.

Geological facts

The visible glitter and layered texture result from aligned mica flakes reflecting light. It may also contain garnet, chlorite, or hornblende, which can help identify its specific variety.

Field identification & locations

Common in regional metamorphic belts and mountainous areas. Look for pronounced foliation, mica flakes that split into thin sheets, and a layered texture; a hand lens or streak/cleavage tests can confirm mica.