Bornite
Bornite (Copper Iron Sulfide) · Mineral Specimen / Copper Ore
Crystal System
Orthorhombic (pseudocubic); typically occurs in massive or granular habits, rarely as distinct crystals.
Mineral Group
Sulfides
Chemical Formula
Cu5FeS4 (often with trace amounts of Ag, Ge, Bi, In, or Pb)
Formation Process
Primarily hydrothermal, occurring in ore veins and at the contact zones of igneous intrusions. It can also form through secondary enrichment in the oxidation zones of copper deposits.
About This Crystal
The specimen displays the characteristic iridescent 'Peacock Ore' tarnish. It features a dark metallic base with vibrant flashes of blue, purple, and green. The surface appears granular and uneven, with high metallic luster where the light hits. While the fresh streak is copper-red, the surface quickly oxidizes to the colorful patina seen here.
Physical Characteristics
Color: Bronze to copper-red on fresh surfaces, iridescent on tarnished surfaces. Streak: Grayish-black. Cleavage: Poor/indistinct. Fracture: Conchoidal to uneven. Specific Gravity: 5.06–5.08. Luster: Metallic. Tenacity: Brittle.
Optical Properties
Opaque mineral; exhibits strong metallic luster. When tarnished, shows thin-film interference producing a range of rainbow-like iridescent colors (iridescence).
Hardness & Durability
Origin Region
Major sources include Butte, Montana (USA); Cornwall (UK); Zacatecas (Mexico); and various mines in South Africa and Chile. Commonly found in hydrothermal veins and porphyry copper deposits.
Hardness & Durability
Mohs hardness: 3. Very soft and brittle. Not suitable for most jewelry due to low scratch resistance and tendency to crumble under pressure.
Care & Maintenance
Clean with a soft, dry cloth; avoid water or chemicals which can damage the iridescent tarnish. Store in a cool, dry place away from harder stones (like quartz) to prevent scratching.
Rarity & Value
Relatively common as an ore of copper. Specimens are valued based on the intensity and range of iridescent colors. Often very affordable for collectors.
Special Characteristics
Renowned for its 'Peacock Ore' iridescence caused by the oxidation of copper and iron on the surface. It is a semi-conductor mineral.
Lore & History
Historically known as 'Peacock Ore,' it was named after the Austrian mineralogist Ignaz von Born. In metaphysical traditions, it is often associated with the 'stone of happiness' and believed to help align the chakras, though these remain traditional beliefs rather than scientific facts.