mineral

Polished pyrite (likely)

Pyrite, FeS₂; possibly a pyrite-rich sulfide specimen

AI-generated identification · may be incorrect

Dark metallic gray to brassy-black, strongly metallic luster, opaque, with scattered reflective crystal faces and irregular polishing. Mohs hardness 6–6.5, cubic crystal system, specific gravity about 5.0; cleavage is indistinct and fracture uneven.

Identified September 16, 2026More mineral →

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Physical properties

Formation & geological history

Pyrite forms when iron and sulfur combine in low-oxygen hydrothermal veins, sedimentary rocks, and metamorphic environments, commonly from the Paleozoic to younger geological ages. The specimen appears cut or polished rather than naturally weathered.

Uses & applications

Used historically as a sulfur and iron source and occasionally in scientific demonstrations; attractive polished pieces are sold as curiosities and mineral specimens, but it is not commonly used as jewelry because it can tarnish or oxidize.

Geological facts

Its metallic appearance gives rise to the nickname “fool’s gold,” though pyrite is typically paler, harder, and more brittle than gold. Oxidation can produce acidic iron-sulfate minerals and damage specimens.

Field identification & locations

Look for metallic luster, high density, pale brass-gray color, and lack of gold’s malleability; a streak test is dark greenish-black. Common localities include Peru, Spain, Italy, China, and the United States.