mineral
Pyrite-bearing rock (iron pyrite)
Pyrite, FeS₂, likely disseminated or massive in a host rock
AI-generated identification · may be incorrectBrassy-gold metallic luster with granular, uneven texture; pyrite hardness is 6–6.5 Mohs, cubic crystal system, no prominent cleavage, and specific gravity about 5.0. The specimen appears matrix-rich rather than a clean crystal cluster.
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Physical properties
Brassy-gold metallic luster with granular, uneven texture; pyrite hardness is 6–6.5 Mohs, cubic crystal system, no prominent cleavage, and specific gravity about 5.0. The specimen appears matrix-rich rather than a clean crystal cluster.
Formation & geological history
Forms when iron and sulfur react in low-oxygen hydrothermal, sedimentary, or metamorphic environments; individual grains may range from ancient Precambrian to younger deposits. Exact age and host rock cannot be determined from the image.
Uses & applications
Used historically as a sulfur source and occasionally for sulfuric-acid production; attractive pieces are sold as cabinet specimens, but it is rarely used as a gemstone. It has limited construction value.
Geological facts
Often called “fool’s gold,” pyrite is harder and more brittle than gold and commonly produces a dark streak, unlike gold’s yellow streak. Weathering can generate sulfuric acid and iron-oxide staining.
Field identification & locations
Identify by metallic brass color, angular granular form, high density, and dark greenish-black streak; a steel nail will not easily scratch it, while pyrite can scratch glass. Common worldwide in sedimentary basins, hydrothermal veins, and coal beds.
