Rock Identifier
Weathered metallic sulfide ore, likely pyrite-bearing rock (Pyrite (FeS₂), possibly in a quartz–iron-oxide host) — mineral
mineral

Weathered metallic sulfide ore, likely pyrite-bearing rock

Pyrite (FeS₂), possibly in a quartz–iron-oxide host

AI-generated identification · may be incorrect

Brassy to brown metallic luster with irregular massive grains; pyrite has Mohs hardness 6–6.5, cubic crystal structure, poor cleavage, and specific gravity about 5.0. Brown surface staining suggests oxidation to limonite/goethite; the image does not clearly show diagnostic cubic crystals.

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Physical properties

Brassy to brown metallic luster with irregular massive grains; pyrite has Mohs hardness 6–6.5, cubic crystal structure, poor cleavage, and specific gravity about 5.0. Brown surface staining suggests oxidation to limonite/goethite; the image does not clearly show diagnostic cubic crystals.

Formation & geological history

Likely formed in hydrothermal veins or sedimentary/metamorphic sulfide deposits, commonly from Paleozoic to younger geological systems. Weathering oxidizes pyrite and produces rusty iron-oxide coatings.

Uses & applications

Pyrite is mined for sulfur, sulfuric-acid production, and occasionally gold byproduct; attractive specimens are collected, though this rough piece has limited gemstone value.

Geological facts

Often called “fool’s gold,” pyrite is harder and more brittle than gold and commonly leaves a dark greenish-black streak, whereas gold leaves a yellow streak. Acid drainage can form when pyrite-rich rock is exposed and oxidized.

Field identification & locations

Look for a metallic brass color, high density, and dark streak; a steel file generally scratches weathered material but may not scratch fresh pyrite. Common localities include Spain, Peru, Italy, China, and hydrothermal districts worldwide.