Bornite (Peacock Ore)

Physical Properties

Hardness: 3 (Mohs). Color: Bronze-brown but tarnishes to iridescent blues, purples, and greens. Luster: Metallic. Crystal Structure: Orthorhombic. Cleavage: Poor.

Formation & Geological History

Found in copper deposits, bornite forms in hydrothermal veins and through contact metamorphism. It is often found alongside other sulfides like chalcopyrite and chalcocite.

Uses & Applications

A major ore of copper for industrial mining. Iridescent specimens are popular with mineral collectors and for use in decorative or metaphysical retail.

Geological Facts

Commonly nicknamed 'Peacock Ore' due to the vibrant iridescent tarnish that forms on its surface after exposure to air. This tarnish is an oxidation layer.

Field Identification & Locations

Identify by its heavy weight (high specific gravity) and the distinctive 'oil slick' iridescence. It can be found in major copper mining districts like Montana (USA), Mexico, and Chile.

Identified on: 4/20/2026

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