mineral

Rainbow chalcopyrite (“peacock ore”)

Chalcopyrite, CuFeS₂, commonly artificially tarnished or heat-treated

AI-generated identification · may be incorrect

Brassy metallic sulfide with iridescent blue, purple, green, and gold tarnish; Mohs hardness 3.5–4, metallic luster, tetragonal crystal structure, indistinct cleavage, and specific gravity about 4.1–4.3. The specimen appears to include massive metallic sulfide matrix and small crystalline faces.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Chalcopyrite forms chiefly in hydrothermal copper deposits, porphyry systems, and contact-metamorphic sulfide ores, commonly with pyrite, bornite, and quartz. The rainbow colors usually result from surface oxidation or deliberate treatment rather than primary crystal chemistry; deposits range from Precambrian to modern geological ages.

Uses & applications

A major copper ore; attractive pieces are sold as mineral specimens and occasionally used decoratively, but it is generally unsuitable for jewelry because of softness and tarnishing.

Geological facts

“Peacock ore” is a trade name, not a distinct mineral; naturally iridescent chalcopyrite is often confused with bornite, which is harder to distinguish without testing.

Field identification & locations

Identify by metallic brassy color, heavy feel, softness, and iridescent tarnish; a streak is typically dark greenish-black. Common localities include Mexico, Peru, the United States, Canada, and China.