mineral

Polished pyrite nodule (likely)

Pyrite, FeS₂

AI-generated identification · may be incorrect

Dark bronze-gray metallic luster with rounded, polished form; pyrite is cubic, Mohs hardness 6–6.5, specific gravity about 5.0, and lacks obvious cleavage. The image alone cannot exclude marcasite, hematite, or a metal object, but the appearance is consistent with a polished sulfide specimen.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Pyrite forms in hydrothermal veins and sedimentary rocks, especially coal beds and marine shales, through sulfide precipitation in low-oxygen environments. It occurs from Precambrian to modern geological settings rather than having one specific age.

Uses & applications

Collected as a mineral specimen and sometimes used historically as a sulfur or iron source; generally unsuitable for jewelry because it can tarnish and oxidize. Polished nodules are decorative curiosities.

Geological facts

Its metallic color earned the nickname “fool’s gold,” though gold is much softer and more yellow. Oxidation can produce acidic runoff and rusty iron-sulfate coatings.

Field identification & locations

Check for a bronze-gold tint, high density, metallic sheen, and resistance to a steel knife; cubic crystals or radial striations strongly support pyrite. Common localities include Peru, Spain, Italy, China, and the United States.