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Ore is natural rock or sediment that contains one or more valuable minerals, typically 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.
Limonite is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 2500 BCE.
Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the form of magnetite (Fe
3O
4, 72.4% Fe), hematite (Fe
2O
3, 69.9% Fe), goethite (FeO(OH), 62.9% Fe), limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe).
Ilmenite, also known as manaccanite, is a titanium-iron oxide mineral with the idealized formula FeTiO
3. It is a weakly magnetic black or steel-gray solid. From a commercial perspective, ilmenite is the most important ore of titanium. Ilmenite is the main source of titanium dioxide, which is used in paints, printing inks, fabrics, plastics, paper, sunscreen, food and cosmetics.
Skarns or tactites are hard, coarse-grained metamorphic rocks that form by a process called metasomatism. 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 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 either 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 the original composition of both the hydrothermal fluid and the original composition of the protolith.
Chromite is a mineral that is an iron chromium oxide. It has a chemical formula of FeCr2O4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite(MgCr2O4). A substitution of the element aluminium can also occur, leading to hercynite (FeAl2O4). Chromite today is mined particularly to make stainless steel through the production of ferrochrome (FeCr), which is an iron-chromium alloy.
Metasomatism is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical composition. The minerals which compose the rocks are dissolved and new mineral formations are deposited in their place. Dissolution and deposition occur simultaneously and the rock remains solid.
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.
The Yilgarn Craton is a large craton that constitutes the bulk of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Terrane have been dated at ~4.27 Ga, with one detrital zircon dated as old as 4.4 Ga.
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.
The South Pass greenstone belt is located within the Wyoming craton in the US. The region was the site of Wyoming's initial gold discovery in 1842.
Iron oxide copper gold ore deposits (IOCG) are important and highly valuable concentrations of copper, gold and uranium ores hosted within iron oxide dominant gangue assemblages which share a common genetic origin.
Iron Mountain, in southern Iron County, Utah, United States, that the namesake of Iron County. Its summit is at 7,815 feet (2,382 m)
The Buena Vista Mine is located 21 miles (34 km) south of Lovelock, Nevada. In the past, the area has been known as the Mineral Basin, though another name for the area has been the Buena Vista District. There are at least two other Buena Vista Mining Districts in Nevada, one is located near Unionville, Nevada, the other located in Esmeralda and Mineral counties near the California border. The nearby Buena Vista Hills are named for the mine. The district encompasses roughly 21 square miles (54 km2) of mineral and surface rights, and is one of the largest un-mined iron ore resources in the western United States.
Old Irontown, Old Iron Town, or Irontown, originally Iron City, is an unincorporated community and near-ghost town in Iron County, Utah, United States. It is located in Dixie National Forest, about 22 miles (35 km) from Cedar City. The settlement was founded in 1868 as a second attempt to mine iron from Iron Mountain after a disappointing yield from Cedar City. The colony lasted until 1876, when strife from the Edmunds–Tucker Act and the Panic of 1873 forced its closure. The site was added to the National Register of Historic Places in 1971.
Iron mining in the United States produced 42.5 million metric tons of iron ore in 2015, worth US$3.8 billion. Iron ore was the third-highest-value metal mined in the United States, after gold and copper. Iron ore was mined from nine active mines and three reclamation operations in Michigan, Minnesota, and Utah. Most of the iron ore was mined in northern Minnesota's Mesabi Range. Net exports were 3.9 million tons. US iron ore made up 2.5 percent of the total mined worldwide in 2015. Employment as of 2014 was 5,750 in iron mines and iron ore treatment plants.
A primary mineral is any mineral formed during the original crystallization of the host igneous primary rock and includes the essential mineral(s) used to classify the rock along with any accessory minerals. 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.
The geology of Liberia is largely extremely ancient rock formed between 3.5 billion and 541 million years ago in the Archean and the Neoproterozoic, with some rocks from the past 145 million years near the coast. The country has rich iron resources as well as some diamonds, gold and other minerals in ancient sediment formations weathered to higher concentrations by tropical rainfall.
The geology of Mauritania is built on more than two billion year old Archean crystalline basement rock in the Reguibat Shield of the West African Craton, a section of ancient and stable continental crust. Mobile belts and the large Taoudeni Basin formed and filled with sediments in the connection with the Pan-African orogeny mountain building event 600 million years ago and a subsequent orogeny created the Mauritanide Belt. In the last 251 million years, Mauritania has accumulated additional sedimentary rocks during periods of marine transgression and sea level retreat. The arid country is 50% covered in sand dunes and has extensive mineral resources, although iron plays the most important role in the economy.
Iron Springs, originally Cedar Springs, was a spring in the bed of Iron Springs Creek in what is now Iron County, Utah. The creek originally drained the western side of Cedar Valley before it was settled. Cedar Springs was located in the gap where the creek passed between the mountains of The Three Peaks and Granite Mountain. Cedar Springs was a camp for early travelers on the Mormon Road, after they had made the arduous passage from Johnson's Springs across the marshy and wooded Coal Creek. It was difficult to cross with wagons at that point in Cedar Valley. The road crossed Coal Creek midway across the valley between Johnson Springs and Cedar Springs. The travelers guide, Mormon Waybill described Cedar Spring "... wood plenty food short, Good camp". When Cedar City was established on the upper reach of Coal Creek in 1851, the road was diverted to the easy crossing there and then proceeded across the valley to Iron springs, a longer route but less arduous.
References
- ↑ Bullock, K. C., 1970, Iron Deposits of Utah, Utah Geological and Mineral Survey Bulletin 88, 102 pgs.
- ↑ Mackin, J. (1968). Ridge, John (ed.). Iron Ore Deposits of the Iron Springs District, Southwestern Utah, in Ore deposits of the United States, 1933-1967. New York: The American Institute of Mining, Metallurgical, and Petroleum engineers, Inc. pp. 992–1019.
