metamorphic
Micaceous schist (likely biotite schist)
Schist dominated by biotite mica, quartz, and feldspar
AI-generated identification · may be incorrectTypically Mohs 2.5–3 for biotite and 6–7 for quartz; brown to gray, strongly reflective, foliated, and splits along mica-rich layers. The glittery sheen and platy texture are diagnostic.
Identified More metamorphic →
Explore Micaceous schist (likely biotite schist) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically Mohs 2.5–3 for biotite and 6–7 for quartz; brown to gray, strongly reflective, foliated, and splits along mica-rich layers. The glittery sheen and platy texture are diagnostic.
Formation & geological history
Formed when shale or other clay-rich sedimentary rock undergoes regional metamorphism at moderate to high temperature and pressure, commonly during mountain building; age depends on its geologic setting.
Uses & applications
Used locally as decorative stone, landscaping material, and occasionally facing stone, though mica-rich schist is generally too weak for major construction. Attractive pieces may be collected or used in lapidary displays.
Geological facts
Its pronounced foliation, called schistosity, results from aligned mica crystals. Weathering commonly causes schist to break into thin flakes and can release sparkling mica fragments.
Field identification & locations
Look for parallel, glittering mica flakes and a tendency to split into irregular sheets; a streak or scratch test can distinguish soft mica from embedded quartz. Common worldwide in metamorphic belts, including the Appalachians, Alps, and Himalayas.
More like this
