Chalcopyrite

Chalcopyrite is a copper iron sulfide mineral (CuFeS2) and the single most important ore of copper worldwide. It has a brassy golden-yellow color, often deeper and more golden than pyrite, and frequently develops a colorful iridescent tarnish in blues, purples, and greens.

Material with strong iridescence is sometimes sold as peacock ore, though true bornite is the classic peacock ore. Chalcopyrite is opaque, metallic, and relatively soft, distinguishing it from harder brassy minerals.

It occurs in a wide range of ore deposits around the world and is mined in enormous quantities to supply the global demand for copper.

Chalcopyrite forms in many environments but is most economically important in porphyry copper deposits, where it is disseminated through large igneous intrusions altered by hot fluids. These deposits supply most of the world's copper.

It also forms in hydrothermal veins, contact metamorphic skarns, and sedimentary settings, commonly alongside pyrite, sphalerite, galena, and other sulfides. As it weathers near the surface, it alters to secondary copper minerals such as malachite, azurite, and bornite.

Major sources include Chile, Peru, the United States, and many other copper-producing regions worldwide.

Chalcopyrite is brassy golden yellow, often with iridescent tarnish, and gives a distinctive greenish-black streak. Its key test is hardness: at 3.5-4 it can be scratched by a knife, unlike pyrite (6-6.5), which cannot.

Distinguish it from pyrite (paler, harder, forms cubes) and gold (soft, very heavy, malleable, golden streak). Chalcopyrite is brittle and usually massive or in small wedge-shaped crystals. Its deeper gold color and lower hardness separate it from pyrite.

The iridescent tarnish resembles bornite, but bornite is darker and purpler when fresh. A streak test and hardness check are the most reliable confirmations.

Chalcopyrite's overwhelming importance is as the primary ore of copper, supplying most of the copper used in electrical wiring, plumbing, electronics, and alloys like bronze and brass. It is mined and processed in vast quantities.

It can also carry valuable byproducts, including gold and silver, recovered during copper refining. Attractive iridescent specimens are popular with mineral collectors.

Metaphysically, chalcopyrite (often as peacock ore) is associated with energy, joy, and meditation, traditions that are cultural rather than scientific.