mineral
Pyrite (fool’s gold)
Iron disulfide, FeS₂; commonly a massive or granular sulfide specimen
AI-generated identification · may be incorrectBrassy yellow to gray-gold metallic luster with glittering grains; Mohs hardness 6–6.5, specific gravity about 5.0, cubic crystal system, and poor/indistinct cleavage. The irregular, dark, granular form appears consistent with massive pyrite, though the photograph cannot confirm it definitively.
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Physical properties
Brassy yellow to gray-gold metallic luster with glittering grains; Mohs hardness 6–6.5, specific gravity about 5.0, cubic crystal system, and poor/indistinct cleavage. The irregular, dark, granular form appears consistent with massive pyrite, though the photograph cannot confirm it definitively.
Formation & geological history
Forms in hydrothermal veins and sedimentary environments, especially coal beds and marine sediments, through sulfide-rich fluids or bacterial sulfate reduction. Pyrite ranges from Precambrian to modern geological ages.
Uses & applications
Used historically as a sulfur source and currently for mineral collecting, education, and limited sulfuric-acid production; it has little jewelry value because it tarnishes and oxidizes.
Geological facts
Its metallic color resembles gold, but pyrite is harder, lighter in color, and brittle; a steel or ceramic streak test gives a dark greenish-black streak rather than gold.
Field identification & locations
Common worldwide, including Peru, Spain, Italy, China, the United States, and Canada. Look for a brassy metallic appearance, brittle fracture, and occasional cubic striated crystals; confirm with hardness and streak tests.
