mineral

Chalcopyrite

Chalcopyrite (CuFeS2)

Hardness: 3.5-4 (Mohs); Color: Brassy yellow, often with green/blue tarnish; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Poor; Specific Gravity: 4.1 to 4.3

Hardness: 3
Color: Brassy yellow, often with green/blue tarnish
Luster: Metallic

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 3.5-4 (Mohs); Color: Brassy yellow, often with green/blue tarnish; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Poor; Specific Gravity: 4.1 to 4.3

Formation & geological history

Formed primarily in hydrothermal veins from hot, mineral-rich fluids. It is also found in igneous rocks (magmatic segregation) and metamorphic deposits. Ages range from Precambrian to Cenozoic.

Uses & applications

Predominantly used as the primary ore of copper. It is also used by collectors and occasionally in costume jewelry (often as 'Peacock Ore' when acid-washed to enhance tarnish).

Geological facts

Chalcopyrite is often called 'Fool's Gold,' a name it shares with Pyrite, though Chalcopyrite has a more greenish-yellow hue. It is the most common copper mineral found worldwide.

Field identification & locations

Identify by its brassy yellow color and relatively low hardness (can be scratched by a knife, unlike Pyrite). Commonly found in copper mines in Arizona, Chile, and the DRC.