metamorphic

Mica-rich schist (likely biotite schist)

Biotite–quartz schist; composition chiefly quartz (SiO₂), biotite mica, and feldspar

AI-generated identification · may be incorrect

Usually medium-hard (Mohs ~2.5–7 depending on mineral), brown to bronze and sparkly, with a foliated texture and mica’s perfect one-directional cleavage; mica produces a pearly to vitreous luster. The specimen appears strongly schistose, though the image alone cannot confirm exact composition.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or other clay-rich sediment was subjected to regional metamorphism, typically during mountain building; its age depends on the parent formation and may range from Precambrian to much younger. Mica flakes recrystallized and aligned under heat and pressure.

Uses & applications

Used locally as decorative stone, aggregate, fill, and occasionally roofing or landscaping material; attractive pieces may be collected, but it is generally not a jewelry gemstone.

Geological facts

The glitter comes from reflective mica cleavage surfaces rather than metallic ore. Splitting parallel to foliation and abundant flexible bronze-brown flakes are characteristic of biotite-rich schist.

Field identification & locations

Common in metamorphic belts worldwide, including the Appalachians, New England, Alps, and Himalayan regions. Check for thin, flexible mica sheets, foliation, and a streak that is generally white to gray; avoid confusing it with mica-rich granite or phyllite.