mineral
Pyrite (iron pyrite), likely massive or granular specimen
Pyrite, FeS₂
AI-generated identification · may be incorrectBrassy 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.
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Physical properties
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.
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.
