Bornite (Cu₅FeS₄) is one of the most vivid copper sulfides and a major copper ore. Fresh surfaces show a bronze-pink metallic color, but the mineral rapidly tarnishes to vivid iridescent purple, blue, and gold — the famous “peacock ore” effect treasured by collectors. It is closely associated with chalcopyrite in porphyry copper deposits and frequently forms exsolution intergrowths with it.
Key Facts
- Mohs hardness 3 — softer than chalcopyrite or pyrite.
- Bronze-pink fresh; tarnishes within hours of exposure to vivid iridescence.
- Crystallizes orthorhombic at room temperature; pseudocubic above 228 °C.
- Massive, granular habit dominates; well-formed octahedral crystals are rare and highly prized.
- Major copper byproduct of chalcopyrite-bearing porphyry deposits worldwide.
Notable Chinese Localities
Dexing Copper Mine (Jiangxi) and Daye District (Hubei) produce bornite as porphyry-copper byproducts. Tongling (Anhui) hosts smaller but high-iridescence specimens.
Found at these Localities
- Yangla Copper Mine (羊拉铜矿)
- Tongling Mining District (铜陵矿区)
- Daye District (大冶)
- Hubei (湖北)
- Jiangxi (江西)
