mineral

Bornite (Peacock Ore)

Cu5FeS4 (Copper Iron Sulfide)

Hardness: 3-3.25; Color: Brownish bronze on fresh surface, tarnishing to iridescent purple/blue (peacock hues); Luster: Metallic; Structure: Orthorhombic; Cleavage: Poor; SG: 5.06-5.08

Hardness: 3-3
Luster: Metallic

Identified July 19, 2026More mineral →

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Physical properties

Hardness: 3-3.25; Color: Brownish bronze on fresh surface, tarnishing to iridescent purple/blue (peacock hues); Luster: Metallic; Structure: Orthorhombic; Cleavage: Poor; SG: 5.06-5.08

Formation & geological history

Forms in copper ore deposits through hydrothermal veins or as a secondary mineral in enriched zones of sulfide deposits, often associated with chalcopyrite and chalcocite.

Uses & applications

Major ore of copper; highly popular as decorative specimens for collectors due to its vibrant iridescent colors.

Geological facts

Commonly nicknamed 'Peacock Ore' because of its rapid tarnish that creates a rainbow of colors. Natural bornite is different from chalcopyrite that has been acid-washed to enhance colors, which is also sometimes sold as peacock ore.

Field identification & locations

Identify by its distinct purple/blue metallic tarnish and reddish-brown fresh streak. Found in major mining districts like those in Arizona (USA), Chile, and Kazakhstan.