metamorphic

Likely pyrite-bearing metamorphic rock

Quartz–mica schist or phyllite with disseminated pyrite (FeS₂)

AI-generated identification · may be incorrect

Small, irregular gray-green specimen with a dull to slightly sparkly foliated texture and granular brassy metallic patches, likely pyrite. Hardness is approximately 2–3 for the mica-rich matrix and 6–6.5 for pyrite; pyrite has cubic crystal structure, metallic luster, and no cleavage.

Identified September 7, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when clay-rich sedimentary rock was buried, heated, and compressed during regional metamorphism, with pyrite crystallizing from sulfur- and iron-bearing fluids. Exact age and locality cannot be determined from the photograph.

Uses & applications

Primarily a teaching or collecting specimen; schist may be used decoratively, while pyrite is collected for its metallic crystals. It has little value for jewelry unless attractive crystals are present.

Geological facts

The brassy grains can resemble gold, but pyrite is harder and brittle, whereas gold is very soft and malleable. The apparent green-gray color may reflect chlorite or weathering.

Field identification & locations

Look for planar foliation, mica sparkle, and brassy grains that leave a dark streak and fracture rather than bend. Common in metamorphic belts worldwide; a hand lens and streak test would improve identification.