mineral

Pyrite (likely), “fool’s gold”

Pyrite, FeS₂ (iron disulfide)

AI-generated identification · may be incorrect

Brassy yellow metallic luster with granular/crystalline texture; Mohs hardness 6–6.5, cubic crystal system, poor cleavage, and specific gravity about 5.0. The specimen appears dark, irregular, and weathered rather than showing ideal cubes.

Identified August 18, 2026More mineral →

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Physical properties

Formation & geological history

Forms in sulfur-rich, low-oxygen environments, including hydrothermal veins and sedimentary rocks; deposits range from Precambrian to modern geological ages. It commonly crystallizes from sulfur-bearing fluids reacting with iron minerals.

Uses & applications

Used historically as a sulfur and sulfuric-acid source, and occasionally as an ornamental or teaching specimen; it has little jewelry value because it tarnishes and can oxidize.

Geological facts

Pyrite can resemble gold but is harder, more brittle, and lighter in color; a streak test produces a greenish-black to brown-black streak, unlike gold’s yellow streak.

Field identification & locations

Common in sedimentary rocks, coal beds, hydrothermal veins, and metamorphic deposits worldwide. Confirm with hardness, streak, density, and—ideally—chemical testing; the image alone cannot exclude marcasite or chalcopyrite.