Hematite, also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Fe
2O
3. It has the same crystal structure as corundum (Al
2O
3) and ilmenite (FeTiO
3). With this it forms a complete solid solution at temperatures above 950 °C (1,740 °F).
Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade, regional metamorphism. It is the finest-grained foliated metamorphic rock. Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression.
Banded iron formations are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iron-poor chert. They can be up to several hundred meters in thickness and extend laterally for several hundred kilometers. Almost all of these formations are of Precambrian age and are thought to record the oxygenation of the Earth's oceans. Some of the Earth's oldest rock formations, which formed about 3,700 million years ago (Ma), are associated with banded iron formations.
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 BP.
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).
Minas Gerais ( ) is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte, is a major urban and finance center in Latin America, and the sixth largest municipality in Brazil and its metropolitan area is the third largest in Brazil with just over 5.8 million inhabitants, after those of São Paulo and Rio de Janeiro. Nine Brazilian presidents were born in Minas Gerais, the most of any state. The state has 10.1% of the Brazilian population and is responsible for 8.7% of the Brazilian GDP.
Ouro Preto, formerly Vila Rica, is a Brazilian municipality located in the state of Minas Gerais. The city, a former colonial mining town located in the Serra do Espinhaço mountains, was designated a World Heritage Site by UNESCO due to its Baroque colonial architecture. Ouro Preto used to be the capital of Minas Gerais from 1720 until the foundation of Belo Horizonte in 1897.
Taconite is a variety of banded iron formation, an iron-bearing sedimentary rock, in which the iron minerals are interlayered with quartz, chert, or carbonate. The name "taconyte" was coined by Horace Vaughn Winchell (1865–1923) – son of Newton Horace Winchell, the Minnesota State Geologist – during their pioneering investigations of the Precambrian Biwabik Iron Formation of northeastern Minnesota. He believed the sedimentary rock sequence hosting the iron-formation was correlative with the Taconic orogeny of New England, and referred to the unfamiliar and as-yet-unnamed iron-bearing rock as the 'taconic rock' or taconyte.
Mineiro, Mineirês, or the Brazilian mountain accent is the Brazilian Portuguese term for the accent spoken in the Center, East and Southeast regions of the state of Minas Gerais.
Nova Lima is a municipality of about 87,000 people, whose downtown is located about 20 kilometers south of Belo Horizonte, the capital of the south-eastern Brazilian state of Minas Gerais. Mining is one of the main economical activities of the city, including the extraction of Iron Ore and Gold. The most famous mine in the city is Morro Velho, a gold mine of 2,700 metres (8,900 ft) depth.
Itabirito is a municipality in the Minas Gerais state of Brazil. Its population is estimated to have 52,446 people in 2020. The city belongs to the mesoregion Metropolitan of Belo Horizonte and to the microregion of Ouro Preto.
Itabira is a Brazilian municipality and a major city in the state of Minas Gerais. The city belongs to the Belo Horizonte metropolitan area mesoregion and to the Itabira microregion.
In geology, a redox buffer is an assemblage of minerals or compounds that constrains oxygen fugacity as a function of temperature. Knowledge of the redox conditions (or equivalently, oxygen fugacities) at which a rock forms and evolves can be important for interpreting the rock history. Iron, sulfur, and manganese are three of the relatively abundant elements in the Earth's crust that occur in more than one oxidation state. For instance, iron, the fourth most abundant element in the crust, exists as native iron, ferrous iron (Fe2+), and ferric iron (Fe3+). The redox state of a rock affects the relative proportions of the oxidation states of these elements and hence may determine both the minerals present and their compositions. If a rock contains pure minerals that constitute a redox buffer, then the oxygen fugacity of equilibration is defined by one of the curves in the accompanying fugacity-temperature diagram.
Following are the official winners of the national Brazilian Chess Championships from 1927 to date.
The surface color of the planet Mars appears reddish from a distance because of rusty atmospheric dust. From close up, it looks more of a butterscotch, and other common surface colors include golden, brown, tan, and greenish, depending on minerals.
Ferrous Resources Ltda. is a Brazilian mining company engaged in the research, exploration, exploitation, processing and marketing of iron ore.
Serra do Gandarela National Park is a national park in the state of Minas Gerais, Brazil. It protects a mountainous region holding a remnant of Atlantic Forest that is an important source of water for the city of Belo Horizonte.
The Iron Quadrangle is a mineral-rich region covering about 7,000 square kilometres (2,700 sq mi) in the central-southern part of the Brazilian state Minas Gerais. The area is known for its extensive deposits of gold, diamonds, and iron ore, being the source of approximately 40% of all gold produced in Brazil between the years 1500 and 2000. The deposits themselves pertain to the Minas Supergroup, a sequence of meta-sedimentary rocks initially formed in the Paleoproterozoic, about 2.5 Ga. In the 2010s, there have been two collapses of large tailings dams, which caused extensive damage and loss of life.
The Immediate Geographic Region of Santa Bárbara-Ouro Preto is one of the 10 immediate geographic regions in the Intermediate Geographic Region of Belo Horizonte, one of the 70 immediate geographic regions in the Brazilian state of Minas Gerais and one of the 509 of Brazil, created by the National Institute of Geography and Statistics (IBGE) in 2017.
Adriana Fátima de Araújo, best known as Adriana Araújo, is a Brazilian journalist.
