mineral

Peacock Ore (Bornite or Chalcopyrite treated with acid)

Bornite (Cu5FeS4) or Acid-washed Chalcopyrite (CuFeS2)

Hardness: 3-3.5 on Mohs scale. Color: Iridescent blues, purples, and magentas over a metallic gold/bronze base. Luster: Metallic. Crystal Structure: Orthorhombic/Tetragonal. Cleavage: Poor.

Hardness: 3-3
Luster: Metallic

Identified March 18, 2026More mineral →

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Physical properties

Hardness: 3-3.5 on Mohs scale. Color: Iridescent blues, purples, and magentas over a metallic gold/bronze base. Luster: Metallic. Crystal Structure: Orthorhombic/Tetragonal. Cleavage: Poor.

Formation & geological history

Formed in hydrothermal veins, contact metamorphic zones, and as a primary mineral in basic igneous rocks. The vibrant iridescent colors are typically an oxidation crust formed naturally or enhanced by acid washing.

Uses & applications

Bornite is a significant ore of copper. Peacock ore specimens are widely used for rock collecting, metaphysical purposes, and as decorative ornamental pieces. Rarely used in jewelry due to brittleness.

Geological facts

Natural Bornite naturally tarnishes to iridescent shades, earning it the nickname 'Peacock Ore.' However, most specimens found in gift shops are actually Chalcopyrite that has been dipped in acid to force the colorful oxidation film.

Field identification & locations

Identify in the field by its distinctive metallic luster and 'oil slick' color patterns. Often found in copper mining districts like Butte, Montana, or Cornwall, England. Collectors should look for deep purples and blues that don't rub off easily.

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