mineral

Chalcopyrite

CuFeS2

Hardness: 3.5-4 (Mohs scale); Color: brassy yellow, often with iridescent tarnish; Luster: metallic; Crystal structure: tetragonal; Cleavage: poor/indistinct; Specific gravity: 4.1-4.3

Hardness: 3
Color: brassy yellow, often with iridescent tarnish
Luster: metallic

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 3.5-4 (Mohs scale); Color: brassy yellow, often with iridescent tarnish; Luster: metallic; Crystal structure: tetragonal; Cleavage: poor/indistinct; Specific gravity: 4.1-4.3

Formation & geological history

Forms in hydrothermal veins, contact metamorphic deposits, and as an accessory mineral in igneous rocks. It is majorly found in massive deposits within sulfide ore bodies.

Uses & applications

The primary ore of copper worldwide. While less common, iridescent specimens (often sold as 'Peacock Ore') are popular for collectors and decoration.

Geological facts

It is often confused with pyrite ('Fool's Gold'), but chalcopyrite has a more golden-yellow tint and is softer, yielding to a nail scratch. When exposed to air, it tarnishes into a colorful, iridescent surface.

Field identification & locations

Identify by its distinctive brassy luster, low hardness compared to pyrite, and greenish-black streak. Commonly found in major mining districts in Arizona, Montana, Canada, and Chile.