Rock Identifier
Bornite (Peacock Ore) (Bornite (Cu5FeS4)) — mineral
mineral

Bornite (Peacock Ore)

Bornite (Cu5FeS4)

Hardness: 3 (Mohs scale), Color: Brownish-bronze (fresh surface) to iridescent blue, purple, and green (tarnished surface), Luster: Metallic, Crystal Structure: Orthorhombic/Isometric, Cleavage: Poor, Specific Gravity: 5.06-5.08

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Physical properties

Hardness: 3 (Mohs scale), Color: Brownish-bronze (fresh surface) to iridescent blue, purple, and green (tarnished surface), Luster: Metallic, Crystal Structure: Orthorhombic/Isometric, Cleavage: Poor, Specific Gravity: 5.06-5.08

Formation & geological history

Occurs in hydrothermal veins, contact metamorphic zones, and as a secondary mineral in enriched copper deposits. It is often found in both igneous and metamorphic copper-rich environments.

Uses & applications

A major ore of copper used in industrial electrical wiring and electronics. Also popular among collectors and used in jewelry as 'Peacock Ore'.

Geological facts

Nicknamed 'Peacock Ore' because of its rapid tarnish into vibrant iridescent colors. While natural bornite is iridescent, many commercial 'peacock ore' specimens are actually acid-treated chalcopyrite.

Field identification & locations

Identify in the field by its distinct metallic iridescence and relatively low hardness compared to other metallic minerals. Commonly found in copper mining districts like those in Chile, Arizona, and Cornwall.