mineral

Chalcopyrite

Chalcopyrite (CuFeS2)

Hardness: 3.5-4 (Mohs); Color: Brass yellow to golden; Luster: Metallic; Crystal Structure: Tetragonal; Cleavage: Indistinct; Specific Gravity: 4.1-4.3; Often displays colorful iridescent tarnish (peacock coloring) when weathered.

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

Identified March 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins, contact metamorphic deposits, and as a primary mineral in igneous rocks. It can occur in a wide variety of geological ages, particularly in sulfide-rich environments near tectonic plate boundaries.

Uses & applications

The primary ore mineral for copper production globally. It is also a popular specimen for mineral collectors and is sometimes sold under the trade name 'Peacock Ore' when treated with acid or naturally tarnished.

Geological facts

Chalcopyrite is often confused with Gold or Pyrite, earning the nickname 'Fool\'s Gold.' However, it is softer than pyrite and more brittle than gold. It has been mined for over 5,000 years, dating back to the Bronze Age.

Field identification & locations

Identify in the field by its brassy color, greenish-black streak, and brittleness compared to gold. Commonly found in copper mines in regions like Chile, Arizona (USA), Canada, and Cornwall (UK). Collectors look for well-defined tetragonal crystals.