Bornite
Bornite (Copper Iron Sulfide) · Mineral Specimen / Copper Ore
Crystal System
Orthorhombic (pseudocubic); typically massive, granular, or compact habit as seen in the specimen.
Mineral Group
Sulfides
Chemical Formula
Cu5FeS4
Formation Process
Primarily Hydrothermal; forms in hydrothermal veins, contact metamorphic zones, and as a secondary mineral in the enclave of copper deposits.
About This Crystal
Massive, opaque specimen with an iridescent weathered surface. On fresh fracture, it is bronze-brown, but it quickly tarnishes to purple, blue, and green. It has a metallic luster and uneven to subconchoidal fracture.
Physical Characteristics
Color: Bronze to copper-red on fresh surfaces, tarnishing to iridescent blues/purples. Streak: Grayish-black. Specific Gravity: 5.06–5.08. Non-fluorescent. Brittle tenacity.
Optical Properties
Opaque; metallic luster. No refractive index for light transmission. Highly reflective under polarized light in polished sections (anisotropy).
Hardness & Durability
Origin Region
Commonly sourced from Mexico, Peru, Butte (Montana, USA), and Cornwall (England).
Hardness & Durability
Mohs hardness 3.0. Low durability; very soft and brittle. Not suitable for jewelry wear due to its ease of scratching and fracturing.
Care & Maintenance
Avoid chemicals, acids, and ultrasonic cleaners. Clean only with a dry or slightly damp soft cloth. Store in a dry environment to prevent further oxidation/tarnish degradation.
Rarity & Value
Relatively common as a copper ore. Mineral specimens are valued by collectors for irridescence; high-quality colorful 'peacock ore' specimens are popular but inexpensive.
Special Characteristics
Known as 'Peacock Ore' due to the vivid iridescent tarnish caused by the oxidation of copper and iron on the surface.
Lore & History
Named in 1845 after Austrian mineralogist Ignaz von Born. Traditionally associated with the solar plexus chakra and believed in lore to protect against negative energy and promote happiness.