mineral

Peacock ore (likely chalcopyrite)

Iridescent tarnished chalcopyrite, CuFeS₂; sometimes marketed as bornite, Cu₅FeS₄

AI-generated identification · may be incorrect

Brassy metallic sulfide with vivid purple, blue, green, and gold tarnish; Mohs hardness 3.5–4, metallic luster, opaque, massive to granular, and relatively heavy (specific gravity about 4.1–4.3). The specimen appears naturally rough but may be acid-treated to intensify its colors.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal copper deposits, commonly with pyrite, sphalerite, and quartz, through sulfide precipitation in veins and replacement zones. Such deposits range from Precambrian to Cenozoic in age.

Uses & applications

Used primarily as a decorative mineral and teaching or collector specimen; copper sulfide ores are industrially important sources of copper, though this small colorful piece has negligible ore value.

Geological facts

“Peacock ore” is a trade name rather than a single mineral; strongly iridescent pieces sold commercially are often treated chalcopyrite. Bornite is naturally more commonly blue-purple and has a softer hardness of about 3.

Field identification & locations

Identify by metallic brassy areas, heavy feel, softness, and rainbow tarnish; it will not scratch glass and may leave a dark streak. Common localities include Mexico, Peru, Arizona, Montana, and Cornwall.