mineral

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Hardness: 3.5-4 (Mohs scale), Color: Brass yellow to golden with iridescent tarnish, Luster: Metallic, Crystal Structure: Tetragonal, Cleavage: Poor, Specific Gravity: 4.1-4.3

Hardness: 3

Identified June 15, 2026More mineral →

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Physical properties

Hardness: 3.5-4 (Mohs scale), Color: Brass yellow to golden with iridescent tarnish, Luster: Metallic, Crystal Structure: Tetragonal, Cleavage: Poor, Specific Gravity: 4.1-4.3

Formation & geological history

Forms primarily in hydrothermal veins and through magmatic segregation. It can be found in a variety of environments from high-temperature igneous rocks to low-temperature contact metamorphism.

Uses & applications

The most important ore of copper worldwide. While too soft for standard jewelry, iridescent specimens (often called Peacock Ore) are popular in the gem and mineral collecting trade.

Geological facts

Often mistaken for gold or pyrite, earnng it the nickname 'Peacock Ore' when it shows multi-colored tarnishing. It is the primary source of copper used in piping and electrical wiring.

Field identification & locations

Identify by its brass-yellow color, metallic luster, and distinguishing it from gold by its brittleness and from pyrite by its lower hardness (it can be scratched by a knife). Common in Arizona, Montana, and Peru.