Copper native

Copper ore minerals maybe classified as primary, secondary, oxidized, and native copper. Primaryrninerals were concentrated in ore bodies by hydrothermal processes secondary minerals formed when copper sulfide deposits exposed at the surface were leached by weathering and groundwater, and the copper reprecipitated near the water table (see Metallurgy, extractive). The important copper minerals are Hsted in Table 1. Of the sulfide ores, bornite, chalcopyrite, and tetrahedrite—teimantite are primary minerals and coveUite, chalcocite, and digenite are more commonly secondary minerals. The oxide minerals, such as chrysocoUa, malachite, and azurite, were formed by oxidation of surface sulfides. Native copper is usually found in the oxidized zone. However, the principal native copper deposits in Michigan are considered primary (5). 

Most copper deposits are (/) porphyry deposits and vein replacement deposits, (2) strata-bound deposits in sedimentary rocks, (J) massive sulfide deposits in volcanic rocks, (4) magmatic segregates associated with nickel in mafic intmsives, or (5) native copper, typified by the lava-associated deposits of the Keweenaw Peninsula, Michigan. 

Hydrometallurigcal Processes. In hydrometaHurgical processes, metal values and by-products are recovered from aqueous solution by chemical or electrolytic processes. Values are solubilized by treating waste, ore, or concentrates. Leaching of copper ores in place by rain or natural streams and the subsequent recovery of copper from mnoff mine water as impure cement copper have been practiced since Roman times. Most hydrometaHurgical treatments have been appHed to ores or overburden in which the copper was present as oxide, mixed oxide—sulfide, or native copper. PyrometaHurgical and hydrometaHurgical processes are compared in Reference 34. 

Berg-kalk, m. rock time (Geol.) mountain limestone. -kiesel, m. rock flint, chert felsite. -kohle,/. (mineral) coal, -kork, m. mountain cork (a light form of asbestos), -kreide, /. rock lime, -kristall, -krystall, m. rock crystal (transparent quartz), -kupfer, n. native copper, -lasur, /. azurite. -leder, n. mountain leather (a form of asbestos), -maun, m miner. 

This element occurs in nature in the uncombined state as native copper and in the combined state as various oxides, sulfides, and carbonates. The chief mineral is chalcopyrite, CuFeS2, from which the element is extracted by roasting (heating in air) followed by reduction. The roasting reaction can be written... 

Okuyama altaite, hessite, tetradymite electrumm chalcopyrite, native copper, hematite, pyrite. sfdialerite quartz, chalorite, sericite... 

A single metal may be extracted from several minerals. Thus there are many minerals of copper, such as chalcocite, bornite, chalcopyrite, cuprite, native copper, and malachite one or more of these may occur in an individual deposit. Also, more than one metal may be obtained from a single mineral stannite, for example, yields both copper and tin. A mineral deposit, therefore, may yield several metals from different minerals. 

Native Copper, Silver, and Gold Accessible to Early Metallurgists. American Antiquity. 36 (July 1971) 286-321. 

Copper (chemical symbol Cu, from the Latin name of the metal, cuprum), the metal that in Roman times was known as the Cyprian metal (since much of the metal came from Cyprus), is reddish brown, malleable and ductile, and can be easily shaped by cold- or hot-working techniques (see Fig. 35) (Scott 2002). Native copper occurs mainly in the form of boulders, nuggets, dendrites, and laminar outgrowths. It was certainly in its native form that copper was first recognized and used for over five millennia since then, however, the bulk of copper has been derived from copper ores by a variety... 

FIGURE 35 Copper vessel. Basket-shaped copper vessel from the Cave of the Treasure, Nahal Mishmar, Israel. Copper, one of the earliest used metals, has been one of the most important materials in the development of materials technology. Masses of native copper were being pounded into tools and ornaments as early as the tenth millennium b.c.e. Because of the relative ease with which it is recovered from its ores, its remarkable physical properties (high ductility, malleability, and thermal conductivity) and its resistance to corrosion, copper has been among the major metals in terms of the quantities consumed. 

Wayman, M. L. (1989), Native copper Humanity s introduction to metallurgy , in Wayman, M. L. (ed.), All That Glisters Readings from Metallurgical History, Canadian Institute of Mining and Metallurgy, Montreal. 

One simple yet successful technique for cleaning green, faded copper utensils, brass items, and chrome surfaces recommends the use of vinegar Pour vinegar and salt over copper surface and rub. Even black- or green-coated specimens of native copper can be cleaned with vinegar. Alternative recipes suggest lemon juice, ketchup, or even water in which onions have been boiled. Why do these remedies work ... 

Cleaning Native Copper. Herb Sulsky, Lithosphere, May 1993, Fallbrook Gem and Mineral Society, http //fgms.home.att.net/copper.htm... 

For example, consider copper. Native copper could be worked into various shapes, but was too soft for making tools and swords. Copper smelted from... 

Copper oxide gold ores. Although this ore type is not abundant, they are of significant value because they contain gold. Only a few deposits in Brazil and Australia are known. The copper in these ores is represented by cuprite, native copper, antlerite and tenorite. The gold is associated with cuprite, as an auricupride and several sulphosalts. The major problem associated with treatment of this ore type is the presence of large amounts of clay slimes in the form of iron hydroxide and illite. 

Hancock, R.G.V., Pavlish. L.A., Farquhar, R.M., Salloum, R. Fox, W.A. and Wilson, G.C. (1991). Distinguishing European trade copper and northeastern North American native copper. Archaeometry 33 69-86. 

Kuleff, I. and Pernicka, E. (1995). Instrumental neutron activation analysis of native copper - some methodological considerations. Journal of Radioanalytical and Nuclear... 

Mauk, J. L. and Hancock, R. G. Y. (1998). Trace element geochemistry of native copper from the White Pine mine, Michigan (USA) implications for sourcing artefacts. Archaeometry 40 97-107. 

Blank native copper B bornite Cp chalcopyrite M mowakite D domeykite Cc chalcocite... 

Native copper has a distinctive reddish/brown color. Its first oxidation state (+1) forms compounds with copper ions named cuprous, also referred to as copper(I), and these ions are easily oxidized with elements in group 16 (e.g., oxygen and sulfur) and elements in group 17 (the halogens). 

Copper is distributed widely in nature as sulfides, oxides, arsenides, arsenosulfides, and carbonates. It occurs in the minerals cuprite, chalcopyrite, azurite, chalcocite, malachite and bornite. Most copper minerals are sulfides or oxides. Native copper contains the metal in uncombined form. The principal copper minerals with their chemical compositions and percentage of copper are listed below ... 

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