mineral

Pyrite (iron pyrite), likely massive or granular specimen

Pyrite, FeS₂

AI-generated identification · may be incorrect

Brassy yellow to bronze metallic luster with granular, sparkly surfaces; Mohs hardness 6–6.5, cubic crystal system, indistinct cleavage, and specific gravity about 5.0. The irregular, dark weathered matrix makes this less likely to be native gold, which is softer and more malleable.

Identified September 1, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, sedimentary rocks, and metamorphic environments when iron-bearing fluids react with sulfur; deposits range from ancient Precambrian to modern geological settings. This specimen may be a pyrite-rich sulfide ore fragment.

Uses & applications

Used historically as a sulfur source and minor iron ore; today it is primarily a collector specimen and teaching sample, with limited industrial value.

Geological facts

Pyrite is commonly called “fool’s gold,” but it is harder, more brittle, and usually less yellow than gold. Weathering can produce sulfuric acid and iron oxides, potentially damaging specimens or nearby materials.

Field identification & locations

Look for metallic brass color, brittle fracture, and cubic or granular crystals; a streak test gives a greenish-black to brownish-black streak, unlike gold’s yellow streak. Common sources include Peru, Spain, Italy, China, and the United States.