Mining districts

The most important body of primary silver ore in the United States in the 1990s is located in Silver Valley, the Coeur d Alene Mining District of Shoshone County, Idaho, which produces >200 t/yr of silver. The main ore mineral is tetrahedrite [12054-35-2] associated with sulfides of lead, copper, iron, and 2inc. 

U.S. silver production from 1985 to 1994 averaged 1588 t/yr. Less than one quarter of this output comes from silver mine districts, however. About half is as by-product of gold mines about one quarter comes from copper and lead—2inc mines. The silver production in Mexico from 1985 to 1994 averaged 2256 t/yr, and Pern, at the southern extremity of the cordillera, where silver is a by-product of copper and lead—2inc mines, averaged 1810 t/yr. 

Figure 1.10. The distribution of the Green Tuff belt of Japan and the Kuroko-type massive sulfide deposits within it. Major mining districts are labeled and ore deposit clusters outlined (Cathles, 1983a).

District and regional zonings (Park and Macdiarmid, 1963) are generally not found in Cu-Pb-Zn mine district nor in Au-Ag mine district. 

These detailed studies on individual mine district suggest that carbon in carbonates was derived from the country rocks underlying the ore deposits and oxygen in ore fluids is controlled by origin of ore fluids (mostly meteoric water) and boiling of ore fluids. 

Shikazono (1985a) has studied hydrothermal alterations in the epithermal Au-Ag mine district in Izu Penin.sula, middle part of Honshu, and indicated that (1) the propylitic alteration occurs widely in the district (2) at the centre of the district and stratigraphically upper horizon, there exists advanced argillic alteration (3) epithermal Au-Ag vein-type deposits are distributed at marginal zone in the district (Fig. 1.125) ... 

Shikazono et al. (2002) considered the depositional mechanism of quartz and cristobalite and the change in silica concentration of fluid migrating through the altered rocks in the Hishikari mine district based on kinetics-fluid flow mixing model. Their discussion is summarized below. 

Unfortunately tectonic situations of the regions other than Northeast Honshu of Neogene age are not well understood. However, it seems evident that even in the regions other than Northeast Honshu epithermal Au-Ag vein-type deposits formed when the uplift started and the area of land expanded. In addition to the paleontologic data, the country rocks of epithermal Au—Ag mine districts also suggest that epithermal Au-Ag vein-type deposits have formed under the subaeiial condition welded tuff occasionally occurs in the mine area (e.g., Sado, Nebazawa, Northeast Hokkaido) and in general submarine sedimentary rocks and volcanic rocks are poor or absent in the Au-Ag mine districts (e.g., epithermal An-Ag vein-type deposits in Kyushu). 

The deposits are characterized by conspicuous metal zoning and polymetallic mineralization. From the centre to margin of the mine district, the following zonings are recognized Sn-W-Bi-Cu zone, Cu-As-Zn zone, and Zn-Pb-Cu-As zone (Nakamura, 1970). 

Barton, P.B. Jr., Bethke, P.M. and Roedder, E. (1977) Environment of ore deposition in the Creede mining district, San Juan Mountains. Colorado III. Progress toward interpretation of the chemistry of the ore-forming fluid for the OH vein. Econ. Geol, 72, 1-25. 

Casadevall, T. and Ohmoto, H. (1977) Sunnyside mine. Eureka mining district. Sun Juan County Geochemistry of gold and base-metal ore deposition in a volcanic environment. Econ. GeoL, 72, 1285-1320. Cathelineau, M. and Nieva, D. (1985) A chlorite geothermometer. The Los Azufres (Mexico) geothermal system. Contr. Mineral. Petrol., 91, 235-244. 

Ferguson, H.G. (1929) The mining districts of Nevada. Econ. Geol, 24, 131-141. 

Inome, X, Tomita, K., Yamamoto, M. and Oba, N. (1981) On alteration minerals in the Fuke mining district, Kagoshima Prefecture. J. Min. Soc. Jpn. Spec. Issue, 15, 116-132 (in Japanese with English abst.). 

Izawa, E., Tsujimoto, T. and Sano, M. (1987) Enrichment and depletion of elements in the hydrothermal system of the Kushikino gold mining district, Japan. Mining Geology, 37, 85 (in Japanese with English abst.). 

Konno, H., Ishikawa, Y. and Matsueda, O. (1984) Alteration mechanism of andesite in the Hosokura mining district, Miyagi Prefecture. Abst. Annual Joint Meeting of the Soc. Mining Geol. Jpn., Jpn. Assoc. Mineral. Petrol, and Econ. Geol. and Mineral Soc. Jpn., p. 99 (in Japanese). 

Otagaki, T. (1951) Geology and ore deposits of Numanoue mining district, Kitami, Hokkaido. Hokkaido Chishitsuyoho, 18, 5-17 (in Japanese). 

Shikazono, N. (1985a) Mineralogical and fluid inclusion features of rock alterations in the Seigoshi gold-silver mining district, western part of Izu Peninsula, Japan. Ghent. Geol, 213-230. 

Shikazono, N. (1988a) Oxygen and carbon isotopic ratios of calcite and evolution of hydrothermal activities in the Seigoshi gold-silver mining district, Japan. Mining Geology Special Issue, 12, 1-16. 

Tonopah, Comstock Lode, and Goldfield mining districts, Nevada. Econ. Geol., 68, 747-764. 

Shinozuka et al. (1999) analyzed the host volcanic and intrusive rocks in the Minamidani mine district in the Maizuru tectonic Belt and found that these rocks formed in an island arc back-arc system near Laurasia during late Paleozoic. Probably the Yanahara deposits, one of the representative Hitachi subtype deposits, were formed in an island arc back-arc system as same as the Minamidani. Sato and Kase (1996) thought that the Hitachi-subtype deposits formed in back-arc rift or continental rift (Table 2.21). 

In the other areas, generally, the host rocks weakly suffered regional and contact metamorphisms but suffered ocean-floor hydrothermal alteration. For example, hydrothermal alteration mineral assemblages in the Minamidani mine district in the Maizuru range from prehnite-pumpellyite facies to a transition state from green schist to amphibolite... 

According to Kase and Yamamoto (1985), Co and Ni contents of pyrite are higher in the Fudotaki deposits than in the Fujimi deposits in the Hitachi mine district (Fig. 2.54... 

Davis A, Ruby MV, Bergstrom PD. 1992. Bioavailability of arsenic and lead in soils from the Butte, Montana, mining district. Environmental Science Technology 26 461-468. 

Davis A, Ruby MV, Bergstrom, PD. 1994. Factors controlling lead bioavailabiltiy in the Butte mining district, Montana, USA. Environmental Geochemistry and Health 16 147-157. 

In comparison, higher THg levels (up to 9 pg/g dw) have been reported in the Almaden mercury mining district (Ciudad Real, Spain) [51], which can be regarded as the largest geochemical anomaly of mercury on Earth. 

White-tailed deer, Odocoileus virginianus-, Texas 1979-80 uranium mining district vs. reference site ... 

Niethammer, K.R., R.D. Atkinson, T.S. Baskett, and F.B. Samson. 1985. Metals in riparian wildlife of the lead mining district of southeastern Missouri. Arch. Environ. Contam. Toxicol. 14 213-223. 

Mann, H. and W.S. Fyfe. 1988. Biogeochemical cycling of the elements in some fresh water algae from gold and uranium mining districts. Biorecovery 1 3-26. 

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