mineral

Chalcopyrite (Peacock Ore)

Copper Iron Sulfide (CuFeS2)

AI-generated identification · may be incorrect

Hardness: 3.5-4 Mohs; Color: Brass yellow to golden; Luster: Metallic; Iridescent tarnish (blue, purple, magenta); Crystal Structure: Tetragonal; Specific Gravity: 4.1-4.3

Hardness: 3
Color: Brass yellow to golden
Luster: Metallic

Identified July 10, 2026More mineral →

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Physical properties

Hardness: 3.5-4 Mohs; Color: Brass yellow to golden; Luster: Metallic; Iridescent tarnish (blue, purple, magenta); Crystal Structure: Tetragonal; Specific Gravity: 4.1-4.3

Formation & geological history

Forms primarily in hydrothermal veins, contact metamorphic deposits, and as a magmatic segregation in igneous rocks. Often associated with pyrite, quartz, and fluorite.

Uses & applications

Major ore of copper. Also used as decorative specimens for collectors and in jewelry as 'Peacock Ore' when treated with acid or naturally tarnished.

Geological facts

Often confused with Pyrite but is softer and more yellow. When exposed to air or acid, it develops a vibrant, iridescent oxide layer known as 'Peacock Ore'.

Field identification & locations

Identified by its brassy color, low hardness (scratched by a knife), and typical iridescent tarnish. Found worldwide in major copper mines like those in Montana, Arizona, and Mexico.