mineral

Likely bornite (“peacock ore”) with chalcopyrite

Bornite, Cu₅FeS₄, commonly intergrown with chalcopyrite, CuFeS₂

AI-generated identification · may be incorrect

Metallic sulfide specimen with dark gray-black surfaces and iridescent purple, blue, green, and yellow tarnish; Mohs hardness 3–3.25 (bornite) and 3.5–4 (chalcopyrite), opaque, with generally massive rather than visible crystal structure and indistinct cleavage.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal copper ore deposits, often associated with chalcopyrite, pyrite, quartz, and other sulfides; mineralization ranges from ancient Precambrian to geologically recent deposits.

Uses & applications

Primarily an important copper ore; colorful pieces are sold as inexpensive cabinet specimens and occasionally used in mineral collections, not fine jewelry.

Geological facts

The vivid “peacock” colors are a thin oxidation film, not the inherent color of fresh bornite; heating or polishing can intensify or remove the iridescence.

Field identification & locations

Likely identification requires metallic luster, high density, softness, and copper-bearing sulfide associations; common sources include Arizona, Montana, Peru, Mexico, Cornwall, and Kazakhstan. A copper-streak or chemical test is more diagnostic than color alone.