metamorphic

Dark foliated metamorphic rock, likely schist

Mica schist, probably muscovite–biotite schist

AI-generated identification · may be incorrect

Very dark gray, fine-grained and visibly flaky/foliated, with a dull to slightly micaceous luster. Typical hardness is about 2–3 across mica surfaces and 5–7 for quartz; cleavage is strong along mica layers, and specific gravity is roughly 2.7–2.9.

Identified September 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when clay-rich sedimentary rock was buried and subjected to elevated temperature and directed pressure, aligning mica into foliation. It commonly forms during regional metamorphism in mountain belts, usually over millions of years; its precise age cannot be determined from the image.

Uses & applications

Used locally as decorative stone, landscaping material, and occasionally building facing; attractive mica-rich pieces are collected, though this small specimen has little commercial value.

Geological facts

The silvery or dark glitter and tendency to split into thin sheets are characteristic of mica-bearing schist. The specimen could also be a fine-grained phyllite or mica-rich gneiss, which cannot be distinguished confidently from this photograph.

Field identification & locations

Look for planar layers, sparkly mica flakes, and uneven splitting rather than vesicles or glassy fracture; a streak, hardness, and close inspection of foliation would help confirm it. Common in metamorphic terrains worldwide, including the Appalachians, Alps, Himalayas, and Precambrian shields.