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Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit. Ore is extracted from the earth through mining and treated or refined, often via smelting, to extract the valuable metals or minerals. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining, and is therefore considered an ore.
Chalcopyrite ( KAL-kə-PY-ryte, -koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.
Sphalerite is a sulfide mineral with the chemical formula (Zn,Fe)S. It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Valley type, and volcanogenic massive sulfide deposits. It is found in association with galena, chalcopyrite, pyrite, calcite, dolomite, quartz, rhodochrosite, and fluorite.
Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and created by volcanic-associated hydrothermal events in submarine environments.
The Sullivan Mine is a now-closed conventional–mechanized underground mine located in Kimberley, British Columbia, Canada. The ore body is a complex, sediment-hosted, sedimentary exhalative deposit consisting primarily of zinc, lead, and iron sulphides. Lead, zinc, silver and tin were the economic metals produced. The deposit lies within the lower part of the Purcell Supergroup and mineralization occurred about 1470 million years ago during the late Precambrian (Mesoproterozoic).
Various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
Sedimentary exhalative deposits are zinc-lead deposits originally interpreted to have been formed by discharge of metal-bearing basinal fluids onto the seafloor resulting in the precipitation of mainly stratiform ore, often with thin laminations of sulphide minerals. SEDEX deposits are hosted largely by clastic rocks deposited in intracontinental rifts or failed rift basins and passive continental margins. Since these ore deposits frequently form massive sulfide lenses, they are also named sediment-hosted massive sulfide (SHMS) deposits, as opposed to volcanic-hosted massive sulfide (VHMS) deposits. The sedimentary appearance of the thin laminations led to early interpretations that the deposits formed exclusively or mainly by exhalative processes onto the seafloor, hence the term SEDEX. However, recent study of numerous deposits indicates that shallow subsurface replacement is also an important process, in several deposits the predominant one, with only local if any exhalations onto the seafloor. For this reason, some authors prefer the term "Clastic-dominated zinc-lead deposits". As used today, therefore, the term SEDEX is not to be taken to mean that hydrothermal fluids actually vented into the overlying water column, although this may have occurred in some cases.
Kambalda type komatiitic nickel ore deposits are a class of magmatic iron-nickel-copper-platinum-group element ore deposit in which the physical processes of komatiite volcanology serve to deposit, concentrate and enrich a Fe-Ni-Cu-(PGE) sulfide melt within the lava flow environment of an erupting komatiite volcano.
A polymetallic replacement deposit, also known as carbonate replacement deposit or high-temperature carbonate-hosted Ag-Pb-Zn deposit, is an orebody of metallic minerals formed by the replacement of sedimentary, usually carbonate rock, by metal-bearing solutions in the vicinity of igneous intrusions. When the ore forms a blanketlike body along the bedding plane of the rock, it is commonly called a manto ore deposit. Other ore geometries are chimneys and veins. Polymetallic replacements/mantos are often stratiform wall-rock replacement orebodies distal to porphyry copper deposits, or porphyry molybdenum deposits. The term manto is from the Spanish word for mantle, or cloak, although the geologic manto is more like a mantle roll than a sheetlike structure.
Seafloor massive sulfide deposits or SMS deposits, are modern equivalents of ancient volcanogenic massive sulfide ore deposits or VMS deposits. The term has been coined by mineral explorers to differentiate the modern deposit from the ancient.
Carbonate-hosted lead-zinc ore deposits are important and highly valuable concentrations of lead and zinc sulfide ores hosted within carbonate formations and which share a common genetic origin.
The Broken Hill Ore Deposit is located underneath Broken Hill in western New South Wales, Australia, and is the namesake for the town. It is arguably the world's richest and largest zinc-lead ore deposit.
Uranium ore deposits are economically recoverable concentrations of uranium within the Earth's crust. Uranium is one of the more common elements in the Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.
The Trans-Hudson orogeny or Trans-Hudsonian orogeny was the major mountain building event (orogeny) that formed the Precambrian Canadian Shield and the North American Craton, forging the initial North American continent. It gave rise to the Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), which is the largest Paleoproterozoic orogenic belt in the world. It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents. The event occurred 2.0–1.8 billion years ago.
The Admiralty mining district is a mining area in the U.S. state of Alaska which consists of Admiralty Island. Silver and base metals are mined, with gold recovered as a by-product.
The Whim Creek Copper Mine is an operating copper oxide mine, located in the City of Karratha in the Pilbara region of Western Australia.
The Bathurst Mining Camp is a mining district in northeast New Brunswick, Canada, centred in the Nepisiguit River valley, and near to Bathurst. The camp hosts 45 known volcanogenic massive sulfide (VMS) deposits typical of the Appalachian Mountains. Some of the ore is smelted at the Belledune facility of Xstrata. Although the primary commodity is zinc, the massive-sulphide ore body produces lead, zinc, copper, silver, gold, bismuth, antimony and cadmium.
The Yukon–Tanana Terrane (YTT) is a tectonic terrane that extends from central Alaska through central Yukon and into northern British Columbia, Canada and Southeast Alaska, USA. Extending over 2000 km, the YTT is the largest tectonostratigraphic terrane in the northern North American Cordillera. The Yukon–Tanana Upland is a physiographic province mostly underlain by rocks of the Yukon–Tanana Terrane.
The Iberian Pyrite Belt is a vast geographical area with particular geological features that stretches along much of the south of the Iberian Peninsula, from Portugal to Spain. It is about 250 km long and 30–50 km wide, running northwest to southeast from Alcácer do Sal (Portugal) to Sevilla (Spain). The mining activity in this region goes back thousands of years.
Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually create metallic-rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals. In some occurrences, minerals can be extracted for a profit by mining. Discovery of mineral deposits consumes considerable time and resources and only about one in every one thousand prospects explored by companies are eventually developed into a mine. A mineral deposit is any geologically significant concentration of an economically useful rock or mineral present in a specified area. The presence of a known but unexploited mineral deposit implies a lack of evidence for profitable extraction.
References
- ↑ Emsbo, P., Seal, R.R., Breit, G.N., Diehl, S.F., and Shah, A.K. (2016)Sedimentary exhalative (sedex) zinc-lead-silver deposit model.. In: U.S. Geological Survey Scientific Investigations Report 2010–5070–N, 57 S, 2016 http://dx.doi.org/10.3133/sir20105070N.
- ↑ Sangster, D., and Scott, S.D. (1976) Precambrian strata-bound massive Cu- Zn-Pb sulfide ores of North America, in Wolf, K.H., ed., Handbook of strata-bound and stratiform ore deposits: Amsterdam, Elsevier, v. 6 p. 129–222.
- ↑ Franklin, J.M., Lydon, J.W. & Sangster, D.F. (1981) Volcanic-associated massive sulfide deposits. In: Skinner, B.J. (Ed.) Economic Geology 75th anniversary volume, p. 485-627.
- ↑ Shanks, W.C.P., III, and Thurston, R., 2012, Volcanogenic Massive Sulfide Occurrence Model.U.S. Geological Survey Scientific Investigations Report 2010–5070–C, 345 p.