mineral

Blue mineral specimen, likely bornite (“peacock ore”)

Bornite, Cu5FeS4, possibly iridescent chalcopyrite (CuFeS2)

AI-generated identification · may be incorrect

Metallic luster with blue-purple iridescence and granular crystalline texture; bornite has Mohs hardness 3–3.25, whereas chalcopyrite is 3.5–4. Both are opaque copper sulfides with poor cleavage and high specific gravity (~4.1–4.3).

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal copper ore deposits, commonly with pyrite, quartz, and other sulfides; deposits range from ancient Precambrian systems to much younger volcanic and sedimentary-hosted ores.

Uses & applications

Primarily an important copper ore and a popular mineral-collecting specimen; iridescent pieces are sold as “peacock ore,” though many are heat-treated chalcopyrite.

Geological facts

The vivid blue, purple, and gold colors are tarnish films produced by oxidation, not the mineral’s fresh internal color. The image is too blurred to distinguish bornite confidently from treated chalcopyrite.

Field identification & locations

Look for metallic heft, opaque dark gray-brown fresh surfaces, and iridescent tarnish; a streak test, hardness test, and chemical or laboratory analysis provide confirmation. Common localities include Montana, Arizona, Peru, Mexico, and Cornwall.