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Ore is natural rock or sediment that contains one or more valuable minerals concentrated above background levels, typically containing metals, that can be mined, treated and sold at a profit. 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. A complex ore is one containing more than one valuable mineral.
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.
Germanite is a rare copper iron germanium sulfide mineral, Cu26Fe4Ge4S32. It was first discovered in 1922, and named for its germanium content. It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite. Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.
Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver.
Skarns or tactites are coarse-grained metamorphic rocks that form by replacement of carbonate-bearing rocks during regional or contact metamorphism and metasomatism. Skarns may form by metamorphic recrystallization of impure carbonate protoliths, bimetasomatic reaction of different lithologies, and infiltration metasomatism by magmatic-hydrothermal fluids. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals. These minerals form as a result of alteration which occurs when hydrothermal fluids interact with a protolith of either igneous or sedimentary origin. In many cases, skarns are associated with the intrusion of a granitic pluton found in and around faults or shear zones that commonly intrude into a carbonate layer composed of either dolomite or limestone. Skarns can form by regional or contact metamorphism and therefore form in relatively high temperature environments. The hydrothermal fluids associated with the metasomatic processes can originate from a variety of sources; magmatic, metamorphic, meteoric, marine, or even a mix of these. The resulting skarn may consist of a variety of different minerals which are highly dependent on both the original composition of the hydrothermal fluid and the original composition of the protolith.
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 produced by volcanic-associated hydrothermal events in submarine environments.
Various theories of ore genesis explain how the various types of mineral deposits form within 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 sulfide 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.
In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite (Cu2S), covellite (CuS), digenite (Cu18S10), and djurleite (Cu31S16) are deposited by the descending surface waters.
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 derived from the Spanish word manto, meaning "mantle" or "cloak".
Deep sea mining is the extraction of minerals from the seabed of the deep sea. The main ores of commercial interest are polymetallic nodules, which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain. The Clarion-Clipperton Zone (CCZ) alone contains over 21 billion metric tons of these nodules, with minerals such as copper, nickel, and cobalt making up 2.5% of their weight. It is estimated that the global ocean floor holds more than 120 million tons of cobalt, five times the amount found in terrestrial reserves.
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.
The Browns polymetallic ore deposit is a large ore deposit located at Mount Fitch, near Batchelor, 64 kilometres south of Darwin, Northern Territory, Australia.
Iron-rich sedimentary rocks are sedimentary rocks which contain 15 wt.% or more iron. However, most sedimentary rocks contain iron in varying degrees. The majority of these rocks were deposited during specific geologic time periods: The Precambrian, the early Paleozoic, and the middle to late Mesozoic. Overall, they make up a very small portion of the total sedimentary record.
In ore deposit geology, hypogene processes occur deep below the Earth's surface, and tend to form deposits of primary minerals, as opposed to supergene processes that occur at or near the surface, and tend to form secondary minerals.
Chumalu is a village in Qareh Poshtelu-e Pain Rural District, Qareh Poshtelu District, Zanjan County, Zanjan Province, Iran. At the 2006 census, its population was 382, in 70 families. The village is the site of epithermal metal deposits, part of the Tarom-Hashtjin Metallogenic Province, and evidence of "ancient workings and dumps" have been found near hydrothermal veins. The total deposits are estimated at 0.2 megatonnes of lead, zinc, copper, gold, and silver ores. There is a high content of silver and base metals, and a high silver-to-gold ratio. The main gangue minerals are quartz, fluorite, rhodochrosite, and calcite. Other features of the Chumalu deposit include crustiform banding, breccia formation, vuggy textures, and the presence of "pyrite, sphalerite, galena, tetrahedrite, chalcopyrite, minor arsenopyrite, and abundant zinc-manganese-iron carbonate minerals".
Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually produce 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.
Queitite is a lead zinc silicate sulphate that was named after the mineral dealer Clive S. Queit, who collected the first specimens. It got approved by the IMA in 1979, and it is an extremely rare secondary mineral.
References
- 1 2 3 4 Vikentyev, I.V.; Damdinov, B.B.; Minina, O.R.; Spirina, A.V.; Damdinova, L.B. (2023). "Classification of Polymetallic Ore-Forming Processes and Transitional VMS–SEDEX–MV-type: the Example of the Giant Ozernoe Deposit in Transbaikalia, Russia". Geology of Ore Deposits. 65 (3): 191–223. doi:10.1134/S1075701523030054. ISSN 1075-7015.
- ↑ "Oʻzbekiston milliy ensiklopediyasi". National Encyclopedia of Uzbekistan (in Uzbek). Tashkent: National Encyclopedia of Uzbekistan State Scientific Publishing House. 2000–2005.
- 1 2 "Polymetallic Vein Deposits". Geologyscience.com.
- ↑ Das, RP; Anand, S. (2017). "Metallurgical processing of polymetallic ocean nodules". In R. Sharma (ed.). Deep-Sea Mining: Resource Potential, Technical and Environmental Considerations (PDF). Springer. pp. 365–94.
- ↑ Barnes, Hubert Lloyd, ed. (1997). Geochemistry of hydrothermal ore deposits (3rd ed.). New York: Wiley. ISBN 978-0-471-57144-5.
- ↑ Hedenquist, Jeffrey W.; Lowenstern, Jacob B. (1994). "The role of magmas in the formation of hydrothermal ore deposits". Nature. 370 (6490): 519–527. doi:10.1038/370519a0. ISSN 0028-0836.
- ↑ Reineck, Hans‐Erich; Wunderlich, Friedrich (1968). "Classification and Origin of Flaser and Lenticular Bedding". Sedimentology. 11 (1–2): 99–104. doi:10.1111/j.1365-3091.1968.tb00843.x. ISSN 0037-0746.
- ↑ Bons, Paul D.; Elburg, Marlina A.; Gomez-Rivas, Enrique (2012). "A review of the formation of tectonic veins and their microstructures". Journal of Structural Geology. 43: 33–62. doi:10.1016/j.jsg.2012.07.005.
- ↑ Mykhailov, V.; Yessendossova, A. (2022). "Factors of Controlling Polymetallic Mineralization on the Example of the Dalnegorsky (Far East) and Uspensky (Central Kazakhstan) Ore Districts". 15th International Conference Monitoring of Geological Processes and Ecological Condition of the Environment. European Association of Geoscientists & Engineers: 1–5. doi:10.3997/2214-4609.2022580041.
