Bornite


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Related to Bornite: chalcocite, Enargite, covellite

bornite

[′bȯr‚nīt]
(mineralogy)
Cu5FeS4 A primary mineral in many copper ore deposits; specific gravity 5.07; the metallic and brassy color of a fresh surface rapidly tarnishes upon exposure to air to an iridescent purple.

Bornite

 

(named after the Austrian metallurgist and mineralogist I. Born, 1742–91), a mottled copper ore, a mineral and a sulfide of copper and iron corresponding to the formula CusFeS4. It contains 52–65 percent copper and 8–12 percent iron. It crystallizes into a cubic system; a modification of a rhombic system is known. Its crystalline structure is of the spinel type. Crystals (cubic or dodecahedral habits) are rare; dense grainy masses are common. They are dark colored, copper red, usually with bright mottled oxide tint in old fractures. Its hardness on the mineralogical scale is 3, and its density is 4,900–5,300 kg/m3.

Bornite is of varying origin. As a hypogene mineral, it is formed in various types of hypothermal deposits. During supergene processes, it is formed in the zone of secondary sulfide concentration. Evolutions of supergene bornite are found in sedimentary rocks, sometimes in the form of pseudomorphoses by organic residues. In hydrothermal deposits, bornite usually is found in association with chalcopy-rite, pyrite, sphalerite, and fahlerz (gray copper ore). It is observed rather frequently in deposits of the type of pyrite seams. Malachite, azurite, cuprite, and other minerals are formed from bornite in oxidation zones. Bornite is an important mineral of copper ores. Deposits of bornite in the USSR are found in the Urals, in the Caucasus, and in Kazakhstan; they are found abroad in the USA, Yugoslavia, South West Africa, and the German Democratic Republic.

References in periodicals archive ?
Assays indicate the copper mineralisation, and in particular the bornite veins, have a high silver content.
These are bornite dominant, followed by chalcopyrite with minor chalcocite, electrum and native gold.
The Arctic deposit is located in the first set of mountains that make up the central part of the Brooks Range on the south side, and the Bornite deposit is sixteen miles south on the north slope of the Cosmos Hills, with the Ambler lowlands in between the two deposits.
Mineralisation at the Attunga Copper Mine is interpreted to be sub-vertical and occurs in garnet-rich calc-silicate skarn with sulphide minerals including chalcopyrite, bornite and molybdenite.
Today the Butte mines are closed and flooded, but its mineralogical legacy of fine specimens remains--most noteably the copper sulfide and sulfosalt minerals such as bornite, chalcocite, chalcopyrite, colusite, covellite, digenite, djurleite, and enargite, and other minerals such as barite, pyrite, quartz and silver.
Preparations were underway to make the Bornite camp fully operational by mid-July with drilling activities expected to be completed by September.
Given the close proximity of Kipushi to several copper smelters in neighbouring Zambia, the intersections of copper-rich chalcopyrite and bornite mineralisation encountered in the drill holes below the former mine workings are highly encouraging.
Mineralisation occurs in garnet-rich calc-silicate skarn with sulphide minerals including chalcopyrite, bornite and molybdenite.
It turned out that a micropatina of bornite coating the crystals was the source of the unique coloration.
Acid base accounting studies of the bornite, chalcocite and magnetite mineralization demonstrate the mineralization is environmentally benign and very highly unlikely to produce acid mine drainage.
The joint-venture agreement also includes Bornite, another known large copper deposit a few miles southwest of Arctic, but the 2015 work is focused on Arctic.