Copper vein deposits

The five types of molybdenum deposits include (i) molybdenum and copper porphyry deposits (ii) Quartz vein and pipes (iii) Pegmatites and apatites dikes (iv) Contact-meta-morphic rocks and tactite bodies of silica bearing limestone and (v) Sedimentary rocks containing bedded deposits. 

Lesser but in some cases significant amounts of rhenium are present in other types of deposits such as skarn deposits (e.g., Needle Mountain-Gaspe Copper), pegmatite-aplite deposits (e.g., Pidgeon Moly) and vein deposits (e.g., Playter, Golconda). 

True vein deposits of uranium are not very common except perhaps in Europe. Uranium in such deposits commonly occurs with. . minerals, such as tin, copper, cobalt, vanadium and arsenic. .. (Bowie, 1972, p. 3). In Europe, as in the U.S.A. (Walker and Osterwald, 1963), the assemblage commonly includes pyrite and other sulfide minerals. Moreover, there is an association of metals in veins which is significant. Walker and Adams (1963, pp. 76—77) state The positive correlation of certain metals — notably molybdenum, manganese, beryllium, tungsten, vanadium, niobium, yttrium, and zirconium — to uranium in veins seems to be reasonably well-established within some deposits, districts, or restricted geographic areas, but none of these metals can be shown to correlate with uranium in all or even a large percentage of vein deposits. In addition to the metals that, when present, appear to correlate intimately with uranium, many other metals such as lead, zinc, copper, silver, and cobalt are associated with uranium in many... 

Figure 34. °Ar/ Ar-Cl/ Ar-K/ Ar mixing diagram for combined in vacuo crushing and stepped heating analyses of vein quartz from the Silverbell copper porphyry deposit Arizona USA. Data form a plane representing a mixture of atmosphere, fluid and solid components The orientation of...

Currently in the United States, most of the lead produced comes from mines in Missouri, Alaska, Idaho, and Montana, primarily from lead-zinc and lead ores (361, 362). Worldwide, major lead deposits exist in association with zinc, silver, and/or copper (362). There are five major geological types of lead deposits volcanic-hosted massive sulfide deposits [Canada, Cyprus, Japan, Australia (Tasmania), Turkey] sediment-hosted deposits of sulfides interbedded with shales, and so on, formed in an anaerobic marine environment [Australia, Canada, Germany, United States (Alaska)] strata-bound carbonate deposits containing sulfide minerals [United States (Mississippi Valley), southern European Alps, Canada, Poland] sandstone-hosted deposits of finely crystalhne sulfides (Canada, France, Morocco, Sweden) and vein deposits of coarsely crystalline sulfide aggregates (western United States, Germany, Japan, Mexico, Peru) (364). The wide variety of compositions seen for lead minerals is illustrated by the representative lead minerals listed in Table XV (3,47). Below, we discuss the lead minerals that are most prevalent in nature in more detail. 

True silver ores, mined entirely for silver, are in our day worked mainly in Mexico and to a small extent in the USA (Utah). Most silver is obtained as a by-product after mining of ores for copper, lead and zinc production. However, as much as 10-15% of the total silver amount comes from vein deposits in which gold is the most valuable element. 

Soil and rock geochemical surveys may be usefully conducted in detailed exploration programmes where the uranium or other associated trace-metal content of the bedrock or soil of an area may be a useful guide to a buried uranium deposit. For example, uranium-, or copper- or molybdenum-in-soil geochemical surveys may be of value in detailed exploration programmes in the search for uranium vein deposits in terrain where uranium vein accumulations occur in association with copper and molybdenum sulphides. 

The fate of ingested copper in patients with Wilson s disease may be summed up briefly as follows. Copper is absorbed from the gut and passes up the portal vein to the liver, in the early or presymptomatic stage of the illness much of the copper is trapped (see Figure 4.4). It is not used at a normal rate in the synthesis of caeruloplasmin and it is probably not excreted at a normal rate either via the bile or the intestinal wall. As the liver proteins become saturated the excess copper is only slowly cleared from the plasma compared with various control groups (see Table 4.2). The high plasma levels of non-caeruloplasmin copper permit deposition of copper at extrahepatic sites, one of which is in the kidneys (see Figure 4.5). As the illness progresses the liver looses its ability to trap copper as also do the kidneys... 

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. 

Almost two-thirds of the world s copper resources are porphyry deposits. The term porphyry is generally appUed to a type of disseminated copper deposit that is hydrothermal in origin and characterized by a large proportion of minerals uniformly distributed as disseminations or in fractures and small veins. Copper contents are generally 1% or less. The most extensive porphyry deposits are located in western Canada, the southwestern United States, Mexico, and western South America. In addition to the porphyrys, there are large bedded copper deposits in Germany, Poland, the CIS, AustraUa, and central Africa. 

Lateral zonation from a sericitic envelope to an intermediate argillic envelope is common in the porphyry copper deposits and vein-type deposits in granodioritic rocks... 

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. 

In 1986, domestic consumption of copper in the United States was 2.14 million metric tons, and mine production was 1.14 million metric tons, mostly from mines in Arizona, New Mexico, and Michigan. The major copper deposits in the United States are of hydrothermal origin and are uniformly distributed in fractures or veins (ATSDR 1990). Copper is the major toxic component in streams impacted by active placer mines (Buhl and Hamilton 1990). About 60% of copper metal is eventually recycled in 1986, smelting of scrap copper produced an additional 0.9 million metric tons of copper. Also in 1986, 1.1 million tons of copper were imported into the United States, mostly from Canada, Chile, Peru, and Mexico (ATSDR 1990). 

In tills method a known copper deposit would be injected in several locations with a solution of dilute sulfuric acid, This acid would percolate through Ihe veins of the ore-bearing rock (usually copper oxidel. The copper would go into solution as copper sulfide and be pumped to the surface by way of several recovery wells. At the surface the copper would be plated onto cathodes (electrowinning process). It is proposed that the dilute solution, when free oF copper, could be returned and circulated up lo several limes. An automatic analytical system would maintain the required strength of the acid solution. Proponents elaim that the cost of Ihe system would be less per ton of copper produced and would increase miner safely. One factor that must he carefully tested is the possible percolation of acid solution into nearby groundwater. 

Native copper commonly occurs in the oxidized /ones of copper deposits in association with cuprite, malachite, and a/urite. The native copper deposits on Ihe Michigan Kceweenau Peninsula represent an exceptional occurrence, The copper occurs there as veins within igneous trap rocks inierhcddeJ Willi conglomerates. Sec also Copper... 

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... 

USA (primarily Arizona, New Mexico, and Utah), 20% the former Soviet Union, 9% Canada, 8% China 8% andZambia, 5%. Presently, recycled scrap metal, or secondary copper, contribntes an additional 25 35% to this yearly output. Open-pit strip mining yields most of the copper ore, which is typically 0.4-1% in copper. Underground methods are used for deeper, vein-type deposits that have a significantly higher copper content (needed to offset the increased mining costs). 

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