Bornite
Bornite (Peacock Ore) · Mineral Specimen / Common Copper Ore
Crystal System
Orthorhombic (pseudocubic); typically occurs as massive or granular habits, rarely as crystals.
Mineral Group
Sulfides
Chemical Formula
Cu5FeS4
Formation Process
Hydrothermal; forms in hydrothermal veins, contact metamorphic zones, and as a primary mineral in igneous rocks.
About This Crystal
An opaque mineral with a metallic luster. Fresh surfaces are bronze to copper-red, but it rapidly tarnishes to iridescent shades of blue, purple, and green.
Physical Characteristics
Color: Bronze/Brown (fresh), Iridescent blue/purple (tarnished); Streak: Grayish-black; Cleavage: Poor; Fracture: Uneven to conchoidal; Specific Gravity: 5.06-5.08; Non-fluorescent.
Optical Properties
Opaque; Metallic luster; No refractive index (opaque); Shows vivid iridescence due to thin-film interference on the tarnished surface.
Hardness & Durability
Origin Region
Notable sources include Montana (USA), Cornwall (UK), Mexico, Peru, and various regions in Chile.
Hardness & Durability
Mohs hardness: 3; Brittle toughness; Low durability for jewelry; sensitive to heat and acids.
Care & Maintenance
Clean with a soft dry cloth; avoid water and chemicals which can strip the colorful tarnish; store separately to prevent scratching.
Rarity & Value
Very common; low price range as a mineral specimen; frequently sold as 'Peacock Ore' (often acid-treated Chalcopyrite).
Special Characteristics
Strong iridescence (schiller effect) on tarnished surfaces; high copper content makes it an important industrial ore.
Lore & History
Historically known as 'Peacock Ore' due to its colors; in folklore, it is associated with happiness and aligning the chakras.