黃銅礦

Chalcopyrite is a brassy gold-coloured sulfide and the world's principal source of copper. Freshly broken it resembles pyrite or gold, but it is softer and frequently develops a spectacular iridescent tarnish of blue, purple and gold that collectors know as peacock ore.

Identifying chalcopyrite

Chalcopyrite is soft (3.5–4) — easily scratched, unlike the harder, paler pyrite it is often confused with — and has a greenish-black streak. Its wedge-shaped (disphenoidal) crystals and brassy, iridescent surfaces are characteristic. It occurs in hydrothermal veins, porphyry copper systems and skarns, usually with other sulfides.

Where it is found

Chalcopyrite is mined for copper around the world. China is a major copper producer; the Daye iron-copper district in Hubei Province and other Chinese skarn and vein deposits yield chalcopyrite with sphalerite, galena, pyrite and quartz. Fine crystallised specimens also come from Spain, the French Alps, and the United States.

What collectors look for

Collectors seek bright, well-formed crystals and naturally iridescent 'peacock' surfaces, as well as aesthetic associations with sparkling quartz, sphalerite or galena. Natural untreated iridescence is valued over artificially tarnished material.