mineral

Peacock ore (bornite/chalcopyrite specimen)

Bornite, Cu₅FeS₄, commonly with chalcopyrite (CuFeS₂)

AI-generated identification · may be incorrect

Metallic luster with vivid iridescent purple, blue, bronze, and gold tarnish; typically massive and granular, with Mohs hardness 3–3.5 (bornite) or 3.5–4 (chalcopyrite), and specific gravity about 4.1–4.3.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

A copper sulfide ore formed in hydrothermal veins and disseminated porphyry-copper deposits, generally through magmatic-hydrothermal activity; individual specimens may be geologically millions to hundreds of millions of years old.

Uses & applications

Primarily a collector specimen and copper ore; not generally used as a gemstone because it is soft and brittle, though polished pieces are sold decoratively.

Geological facts

The rainbow colors are a thin-film oxidation tarnish, not the natural color of fresh sulfide surfaces; commercial “peacock ore” is often artificially acid-treated to intensify the iridescence.

Field identification & locations

Identify by metallic heft, brassy-to-brown sulfide matrix, vivid tarnish, softness, and possible dark gray streak; common sources include Mexico, Peru, Montana, Colorado, and Cornwall. Confirm with chemical or laboratory testing because similar chalcopyrite and bornite are difficult to distinguish visually.