mineral

Polished black-and-gold mineral fragment, likely chalcopyrite

Chalcopyrite (CuFeS₂), possibly tarnished or coated

AI-generated identification · may be incorrect

Metallic luster; dark gray to brassy-gold coloration with iridescent tarnish; Mohs hardness 3.5–4; generally opaque, tetragonal crystal system, with indistinct cleavage. The photograph is too small and blurred for definitive identification.

Identified September 18, 2026More mineral →

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Physical properties

Formation & geological history

Chalcopyrite forms chiefly in hydrothermal copper deposits, commonly with pyrite, sphalerite, and quartz, from Precambrian to modern geological settings. Its surface may oxidize into colorful iridescent sulfide films.

Uses & applications

Important copper ore; attractive polished pieces are sold as mineral specimens, though gem use is uncommon. It is not typically used as a construction stone.

Geological facts

Often called “peacock ore” when artificially or naturally iridescent, although many commercial examples are chemically treated. The golden portion could also represent pyrite or another sulfide.

Field identification & locations

Check for metallic heft, opaque appearance, and a black streak; chalcopyrite is softer than pyrite and can be scratched with a steel knife. Common localities include Peru, Mexico, Canada, the United States, and Kazakhstan.