mineral

Chalcopyrite (Peacock Ore)

Chalcopyrite (CuFeS2)

Hardness: 3.5-4 Mohs; Color: Brass yellow, often tarnishing to iridescent purple, blue, red, and green; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Poor; Specific Gravity: 4.1-4.3

Hardness: 3
Luster: Metallic

Identified July 22, 2026More mineral →

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Physical properties

Hardness: 3.5-4 Mohs; Color: Brass yellow, often tarnishing to iridescent purple, blue, red, and green; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Poor; Specific Gravity: 4.1-4.3

Formation & geological history

Formed in hydrothermal veins, contact metamorphic zones, and magmatic segregation deposits associated with igneous intrusions across various geological eras.

Uses & applications

Major ore of copper; highly popular among mineral collectors for its vivid iridescent tarnish (often enhanced acid-treated as 'peacock ore').

Geological facts

While natural chalcopyrite tarnishes iridescently over time, much of the brightly colored 'peacock ore' sold in rock shops is raw chalcopyrite treated with acid to accelerate and intensify the vivid iridescent patina.

Field identification & locations

Identified by its brassy yellow core, metallic sheen, low hardness (scratched by a knife), and distinctive colorful tarnish. Commonly found in copper mining regions in Peru, Mexico, USA, and South Africa.