metamorphic

Pyrite-bearing metamorphic rock (likely greenschist or phyllite)

Quartz–chlorite–mica schist/phyllite with disseminated pyrite (FeS₂)

AI-generated identification · may be incorrect

Dark gray-green, fine- to medium-grained rock with abundant brassy metallic pyrite flecks; likely hardness 2–6 overall, pyrite 6–6.5 Mohs. Pyrite has cubic crystal structure, metallic luster, pale brass color, and no cleavage; the host appears weakly foliated.

Identified September 8, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when clay-rich sedimentary rock underwent low- to medium-grade regional metamorphism, with pyrite crystallizing during metamorphic or hydrothermal fluid activity. Precise age and locality cannot be determined from the image.

Uses & applications

Primarily a collector specimen; pyrite may be recovered for sulfur or sulfuric-acid production, while the host rock has limited construction value.

Geological facts

Pyrite is commonly called “fool’s gold,” but its brassy color and metallic luster distinguish it from gold. Unlike gold, pyrite is brittle and produces a dark streak rather than a yellow one.

Field identification & locations

Look for metallic brassy grains, cubic forms, brittleness, and a green-gray foliated matrix; a streak test, hardness test, and acid test can help distinguish pyrite-bearing rock from chalcopyrite or gold. Common in metamorphic belts and hydrothermal ore deposits.