mineral

Bornite (“peacock ore”), likely copper sulfide specimen

Bornite, Cu5FeS4; possibly chalcopyrite, CuFeS2, with iridescent tarnish

AI-generated identification · may be incorrect

Metallic luster with strongly iridescent blue, purple, pink, and bronze tarnish; typically massive or granular, opaque, Mohs hardness 3–3.25, poor cleavage, and specific gravity about 4.9–5.3.

Identified September 7, 2026More mineral →

Explore Bornite (“peacock ore”), likely copper sulfide specimen in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Metallic luster with strongly iridescent blue, purple, pink, and bronze tarnish; typically massive or granular, opaque, Mohs hardness 3–3.25, poor cleavage, and specific gravity about 4.9–5.3.

Formation & geological history

Forms in hydrothermal copper-ore veins, porphyry copper deposits, and contact-metamorphic environments through geological time, commonly alongside chalcopyrite, pyrite, and quartz.

Uses & applications

An important copper ore when abundant; small colorful pieces are sold as inexpensive mineral specimens and curiosities, usually not suitable for jewelry because they are soft and tarnish readily.

Geological facts

The vivid colors are a superficial oxidation film rather than the mineral’s fresh surface. The photograph is too low-resolution for certain identification; chalcopyrite is a common look-alike.

Field identification & locations

Identify by its heavy feel, metallic appearance, softness, and rainbow tarnish; a streak test is generally gray-black, and copper sulfides may leave a dark residue. Common localities include Arizona, Montana, Peru, Mexico, and Cornwall.