mineral

Chalcopyrite in Quartz (Gossan/Iron Hat)

CuFeS2 (Chalcopyrite) with SiO2 (Quartz)

Hardness: 3.5-4 (Chalcopyrite), 7 (Quartz); Color: Brass-yellow (tarnish purple/black), white/grey matrix, rusty orange/brown; Luster: Metallic to vitreous; Crystal structure: Tetragonal; Specific gravity: 4.1-4.3

Hardness: 3
Luster: Metallic to vitreous

Identified April 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins at medium to high temperatures. The rusty exterior (gossan) is formed by the oxidation of sulfide minerals through weathering processes.

Uses & applications

Primary ore of copper; specimens are common in mineral collections and used for geological study.

Geological facts

Chalcopyrite is often called 'Peacock Ore' when it exhibits iridescent tarnish. The rusty 'gossan' visible on this specimen is used by prospectors as a surface indicator of valuable mineral deposits beneath.

Field identification & locations

Identify in the field by looking for metallic yellow flashes against a white quartz matrix, often associated with orange-brown iron staining. Can be found globally in copper mines.

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