mineral
Chalcopyrite
Chalcopyrite (CuFeS2)
AI-generated identification · may be incorrectHardness: 3.5-4.0; Color: Brass yellow to golden-yellow, often with an iridescent purple/blue tarnish; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Poor/Indistinct; Specific Gravity: 4.1 to 4.3; Streak: Greenish-black
- Hardness
- 3
- Luster
- Metallic
- Streak
- Greenish-black
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Physical properties
Hardness: 3.5-4.0; Color: Brass yellow to golden-yellow, often with an iridescent purple/blue tarnish; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Poor/Indistinct; Specific Gravity: 4.1 to 4.3; Streak: Greenish-black
Formation & geological history
Formed in primary sulfide deposits within hydrothermal veins, contact metamorphic environments, and through magmatic segregation. It occurs in various geological ages alongside other minerals like pyrite, bornite, and sphalerite.
Uses & applications
It is the world's most important ore of copper. It is also used in metallurgy for gold and silver extraction as a byproduct, and as a popular specimen for mineral collectors and educational purposes.
Geological facts
When chalcopyrite is treated with acid, it develops an intense iridescent tarnish, and in this state, it is frequently sold as 'Peacock Ore' or 'Bornite', though true bornite is a distinct mineral species. It has been used for copper extraction since the Bronze Age.
Field identification & locations
Identify in the field by its brassy yellow color that is more yellow than pyrite and softer than a steel knife (pyrite is harder than steel). It is commonly found in copper mines worldwide, including the southwestern USA, Chile, and Canada. Collectors should look for its distinctive greenish-black streak when scratched on a porcelain plate.
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