CHALCOPYRITE MINERAL FACTS Nevada Turquoise gem stones
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Chalcopyrite Mineral Facts:

Chemical Formula: CuFeS ie., Copper Pyrites, Yellow Copper Ore.

Colors: Brass yellowish, sometimes surfaces are tarnished to iridescent.
streak is greenish black.

Hardness: 3.5 to 4

Density: 4.2
For Both the density and hardness reading for aragonite are higher than normally found for calcite.

Cleavage: No cleavage, fracture is uneven; brittle.

Crystallography: Tetragonal
It occurs both massive and crystallized. From its similarity to pyrite in appearance it is often known as copper pyrites. The mineral often contains small quantities of intermixed pyrite, It also contains in some instances selenium, thallium, gold and silver.

Luster:. Metallic luster.  It is an excellent conductor of electricity.

Optics: (Refractive Index)  a = 1.53; b = 1.68; y = 1.685

Composition, Structure and Associated Minerals:
When subjected to the action of the atmosphere or to percolating atmospheric water chalcopyrite loses its iron component and changes to covellite and chalcocite, producing an iridescent surface. The iron passes into limonite. Bornite,copper and pyrite are also frequent products of its alteration. In the oxidation zone of veins it yields limonite, the carbonates, malachite and azurite, and cuprite (Cu2O). When exposed to the leaching action of water, limonite alone may remain to mark the outcrop of veins, the copper being carried downward in solution to enrich the lower portions of the vein. The deposit of limonite on the surface is known as gossan.  Known sometimes as "fool's gold'' a term which is also applied at times to pyrite. It also impregnates slates and other sedimentary rocks, schists and altered igneous rocks where, in some cases, it is a contact deposit and in others is original. It is also formed by secondary processes causing enrichment of copper sulfide veins. Its most common associates are galena, sphalerite and pyrite.

Identification and Diagnostics
After roasting, and moistening with hydrochloric acid, gives an azure-blue flame. Readily decomposed by nitric acid, giving separated sulphur; solution made ammoniacal gives red / brown precipitate of ferric hydroxide and blue filtrate (copper). Recognized by its brass-yellow color, greenish black streak and its softness. Distinguished from pyrite by its being softer than steel and from gold by its being brittle.

Occurrence, Localities and Origins:
The most common ore of copper. Occurs widely distributed in metallic veins associated with pyrite, pyrrhotite, bornite, chalcocite, tetrahedrite, malachite, azurite, sphalerite, galena, quartz, calcite, dolomite, siderite, etc. May carry gold or silver ore and become an ore of those metals. Often in subordinate amount with large bodies of pyrite, making them serve as low-grade copper ores. Chief ore of copper mines at Cornwall, England; Falun, Sweden; Rio Tinto, Spain; Sudbury, Canada. It is also the important copper ore of the deposits of Falun, Sweden, of Namaqualand in South Africa, those near Copiapo in Chile, those of Mansfeld, Germany. Found widely in the United States but usually in connection with other copper minerals in equal or greater amount; found at Butte, Montana; Bingham, Utah; various districts in California, Colorado, Arizona, Nevada, etc. The name is derived from Greek word meaning brass and from pyrites.

Chalcopyrite is the most important primary ore of copper. A large portion of the copper produced in the world is obtained by the smelting of chalcopyrite and the ores associated with it.

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Please note that the author, Chris Ralph, retains all copyrights to this entire document and it may not be reproduced, quoted or copied without permission.

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