metamorphic

Possibly biotite-rich mica schist or weathered mafic rock

Mica schist; chiefly biotite mica, quartz, and feldspar

AI-generated identification · may be incorrect

Dark brown-black, flaky and sparkly with a micaceous luster; individual mica has Mohs hardness 2.5–3 and perfect basal cleavage. The small, rounded specimen is too indistinct for confident mineral identification from the image alone.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed by regional metamorphism of clay-rich sediment or igneous protolith at moderate temperature and pressure, commonly during mountain building; age cannot be determined visually.

Uses & applications

Schist is used locally as decorative stone, aggregate, and landscaping material; attractive mica-rich pieces are collected but rarely have significant gem value.

Geological facts

Biotite commonly produces the dark color and splits into flexible, shiny sheets. Similar-looking material could be a dark mica-bearing gneiss, phyllite, or altered basalt.

Field identification & locations

Look for planar foliation, glittering flakes, and sheets that separate with a knife; a streak, hardness, magnetism, and close-up view would improve identification. Common in metamorphic belts worldwide.