Chalcopyrite
Chalcopyrite · Mineral Specimen / Industrial Ore
Crystal System
Tetragonal system; commonly occurs in massive, granular, or compact forms, often disparaged as 'Fool's Gold' but with a deeper yellow-green hue than pyrite
Mineral Group
Sulfides
Chemical Formula
CuFeS2 (Copper Iron Sulfide)
Formation Process
Hydrothermal; typically forms in medium-to-high temperature veins or through magmatic segregation in igneous rocks
About This Crystal
An opaque mineral with a brassy-yellow color that often tarnishes to iridescent blues, purples, and greens. It features a metallic luster and can be distinguished by its relative softness compared to pyrite.
Physical Characteristics
Color: Brass yellow; Streak: Greenish-black; Cleavage: Indistinct; Fracture: Uneven to conchoidal; Specific Gravity: 4.1-4.3; Non-magnetic; Non-fluorescent
Optical Properties
Opaque; metallic luster; shows strong anisotropism and moderately high reflectance when polished
Hardness & Durability
Origin Region
Found globally; notable deposits in Arizona (USA), Cornwall (UK), Rio Tinto (Spain), and various South American copper mines
Hardness & Durability
Mohs Hardness: 3.5 - 4.0; Brittle tenacity; easily scratched by a steel knife, making it less durable for jewelry unless treated
Care & Maintenance
Keep dry to prevent oxidation; clean with a soft dry cloth; avoid ultrasonic cleaners or harsh chemicals which may strip the tarnish or damage the surface
Rarity & Value
Very common; primarily valued as the world's most important copper ore; decorative 'Peacock Ore' specimens are affordable and widely available
Special Characteristics
Subject to tarnish which creates a colorful iridescence; often intergrown with quartz, sphalerite, or galena
Lore & History
Historically used as a major source of copper since the Bronze Age; in traditional lore, it is associated with abundance, vitality, and removing energy blockages.