Copper-pyrite deposits

Within the oxidation zones of copper-pyrite deposits very complicated processes take place due to the activity of micro-organisms. The processes can be... 

Selenium was isolated some 35 y after tellurium and, since the new element resembled tellurium, it was named from the Greek askrivr], selene, the moon. The discovery was made in 1817 by the Swedish chemist J. J. Berzelius (discoverer of Si, Ce and Th) and J. G. Gahn (discoverer of Mn) they observed a reddish-brown deposit during the burning of sulfur obtained from Fahlun copper pyrites, and showed it to be volatile and readily reducible to the new element. 

Chalcopyrite or copper pyrite, CuFeS2, is one of the major ores of copper, estimated to account for about 50% of all the element s deposits. Compounds of the chalcopyrite type of the general formula ABC2 (with A = Cu, Ag B = Al, Ga, In ... 

Some of the Kuroko deposits consist predominantly of pyrite containing a small amount of chalcopyrite. The ore deposits consisting predominantly of pyrite, either with an economical value of chalcopyrite or not, are called the Y sub-type deposits, which occur above dacite lava dome or lava flow, while copper-poor deposits occur mostly in pyroclastic rocks and are associated with a large amount of gypsum. The Matsumine deposit in the Hanaoka mine is typical of the Y sub-type. The Matsuki and Takadate deposits in the Matsuki mine are also classed as this sub-type (Kuroda, 1978). Many pyrite-rich ore bodies... 

It is found in most countries of the world, but only a few high-grade deposits are cost-effective to mine. Examples of some of its ores are cuprite (CuO ), tenorite (CuO), malachite [CuCOj Cu(OH)2], chalcocite (Cu S), covellite (CuS), bornite (CugFeS ), and chalcopyrite, also known as copper pyrite. 

The presence of pyrites in mineral veins is frequently betrayed by the brown, rusty appearance of the upper parts of the deposits. This is well exemplified in the case of certain copper lodes, the iron of the contained copper pyrites having become converted into hydrated ferric oxide or rust. Such weathered zones are known as gozzans, and frequently present a cavernous or honeycombed appearance, due to the removal of pyritic material. In France the gozzan is termed the chapeau de fer, and in Germany der eiserne Hut, and an old adage states that4... 

A double sulphide of copper and iron known as Chalmersite, CuFe2S3, occurs in the ore deposits of the Prince of Wales Sound, Alaska,2 and in small quantities in Brazil.3 It is massive, pale yellow in colour, and strongly magnetic, which latter property enables it to be readily separated from the copper pyrites with which it is intimately associated. Density 4 04 to 4 68. The crystals arc rhombic,... 

Traverses were made across four copper-molybdenum deposits and soil gas was collected from holes drilled to a depth of 1.0-1.8 m. The soil air was analysed titrimetrically after absorption in an iodine solution. Control analyses were performed by mass spectrometry. The ore deposits, with widths of between 10-400 m, are associated with skams and granite porphyries. The thickness of the overburden is between 0.6-3 m. The ore minerals are principally chalcopyrite, molybdenite, chalcocite, bomite, galena, sphalerite, magnetite and pyrite. Weathering and secondary enrichment have affected the ores to a maximum depth of 95 m. 

Some of the ores are secondary from the molybdenum point view. This means that the main minerals are copper pyrites and other copper minerals They have been formed from copper-rich solutions containing small amounts of molybdenum, which have penetrated the rocks at high temperature and pressure. The solutions have been heated by magma. During the subsequent coohng the minerals have been formed as deposits along cracks in surrounding rocks. 

Alaska, Washington, and Nevada. Ores of the Southeast Missouri lead belt and extensive deposits such as in Silesia and Morocco are of the replacement type. These deposits formed when an aqueous solution of the minerals, under the influence of changing temperature and pressure, deposited the sulfides in susceptible sedimentary rock, usually limestone and dolomites. These ore bodies usually contain galena, sphalerite, and pyrite minerals, but seldom contain gold, silver, copper, antimony, or bismuth. 

Sulfur is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS, and sphalerite, ZnS (Fig. 15.11). Because these ores are so common, sulfur is a by-product of the extraction of a number of metals, especially copper. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H,S. The low melting point of sulfur (115°C) is utilized in the Frasch process, in which superheated water is used to melt solid sulfur underground and compressed air pushes the resulting slurry to the surface. Sulfur is also commonly found in petroleum, and extracting it chemically has been made inexpensive and safe by the use of heterogeneous catalysts, particularly zeolites (see Section 13.14). One method used to remove sulfur in the form of H2S from petroleum and natural gas is the Claus process, in which some of the H2S is first oxidized to sulfur dioxide ... 

Galena, tetrahedrite-tennantite, mawsonite and native silver occur in the copper rich ores but not in ordinary pyritic ores and copper rich ores most commonly occur as offshoots, tongues and veins in the deformed deposits. This suggests that these minor minerals formed during the metamorphic deformation stage accompanied by recrystallization. 

Skarlygina-Ufimtseva, M. D., Chernyakhov, V. B., Berezkina, G. A. (1976). Biogeochemistry of Pyrite Copper Deposits in the South Ural. Leningrad LGU Publisher, 150 pp. 

Some of the discharged sulfide particles settle onto the chimney s exterior, where they are buried by the outward growth of anhydrite. Sulfide precipitation within the chimneys, causes copper, zinc, and iron sulfides to deposit and partially replace the anhydrite. Chimneys can build to several meters in height and their orifices range in diameter from 1 to 30 cm. Both the smoke and the chimneys are composed of polymetallic sulfide minerals, chiefly pyrrhotite (FeS), pyrite (FeS2), chalcopyrite (CuFeS2), and sphalerite or wurtzite (ZnS). 

They use at Falun [he said] for the manufacture of sulfur, pyrites occurring at various places in the copper mine. The pyrites are often mixed with galena, blende, and several foreign substances. The pyrites are placed on a layer of dry wood, in long, horizontal furnaces, the upper part of which is covered with earth and decomposed pyrites the fumes pass from these furnaces into horizontal tuyeres, the fore part of which is of brick and the rest of wood. The wood is lighted below, and the heat causes the excess sulfur to distil from the lower layer of the pyrite the gaseous sulfur is carried by the current of warm air, and is finally deposited as flowers in the tuyeres,. . . ... 

STANNITE (Mineral). This mineral is a sulfo-stannate of copper and non, sometimes with some zinc, corresponding to the formula. Uii PeSnS j It is tetragonal brittle with uneven fracture hardness, 4 specific gravity, 4.3-4.5 metallic luster color, gray to black, sometimes tarnished by chalcopyiite stieak, black opaque. The mineral occuts associated witli cassilerile, chalcopyiite. tetrahedrite, and pyrite, probably the result of deposition by hot alkaline solution. Stannite occurs in Bohemia Cornwall, England Tasmania Bolivia, and in the United States in South Dakota. It derives its name from the Latin word for tin, stannum. 

The phosphides, arsenides, and antimonides of the other metals are usually dark-coloured substances, with more or less metallic lustre, and therefore conductors of electricity. Some of them occur native for example, smaltine, CoAs2, a common ore of cobalt, forming silver-white crystals copper-nickel, NiAs, red lustrous crystals, and one of the chief nickel ores speiss, a deposit formed in the pots in which smaltine and copper-nickel are fused with potassium carbonate and silica, in the preparation of smalt, a blue glass containing cobalt its formula appears to be Ni8As2. Mispickel, or arsenical pyrites, is a white lustrous substance, of the formula FeSAs. 

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