mineral

Tumbled chalcopyrite (likely)

Chalcopyrite, CuFeS₂

AI-generated identification · may be incorrect

Brassy bronze to tarnished purple-blue iridescence, metallic luster, opaque appearance, and massive rather than visibly crystalline texture; Mohs hardness 3.5–4, specific gravity about 4.1–4.3. The rounded shape indicates tumbling or natural abrasion.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

A copper-iron sulfide formed chiefly in hydrothermal ore veins and porphyry-copper deposits, commonly associated with pyrite, quartz, and sphalerite. Deposits range from Precambrian to younger Phanerozoic ages.

Uses & applications

An important copper ore; colorful polished pieces are sold as decorative or novelty specimens, though much commercial “peacock ore” is artificially tarnished chalcopyrite or bornite.

Geological facts

Purple, blue, and green colors are caused by surface tarnish, not the fresh mineral. It can resemble bornite (“peacock ore”), which is softer and typically more strongly iridescent.

Field identification & locations

Look for metallic brilliance, brassy undertones, heavy feel, and iridescent tarnish; a streak test is dark greenish-black, and it is softer than steel. Common localities include Mexico, Peru, the United States, Canada, and Australia.