mineral

Chalcopyrite on Quartz

Copper Iron Sulfide (CuFeS2)

AI-generated identification · may be incorrect

Hardness: 3.5 to 4 on Mohs scale. Color: Brass yellow, frequently with an iridescent purple, blue, or greenish tarnish (peacock ore). Luster: Metallic. Crystal Structure: Tetragonal. Cleavage: Indistinct. Specific Gravity: 4.1-4.3.

Hardness: 3
Luster: Metallic

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Hydrothermal mineral formed in veins and volcanic deposits associated with medium and high temperature environments. It commonly crystallizes alongside quartz, pyrite, and sphalerite in magmatic sulfide deposits.

Uses & applications

Primary ore of copper metal worldwide. Used extensively in metallurgy, electrical wiring, electronics, alloys like bronze and brass, as well as a popular mineral specimen for collectors.

Geological facts

Often called 'Fool's Gold' alongside pyrite because of its golden metallic luster, but chalcopyrite is softer than pyrite and can be scratched with a steel knife. It exhibits a beautiful rainbow iridescence when tarnished.

Field identification & locations

Identified by its brassy golden-yellow color with metallic luster, iridescent rainbow tarnish, relative softness (can be scratched by steel), and greenish-black streak. Commonly found in copper mines globally, including Peru, Arizona (USA), Canada, and Cornwall (UK).