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Bultfonteinite
Bultfonteinite, originally dutoitspanite, is a pink to colorless mineral with chemical formula Ca2SiO2(OH,F)4. It was discovered in 1903 or 1904 in the Bultfontein mine in South Africa, for which the mineral is named, and described in 1932. Description Bultfonteinite is transparent and pale pink to colorless. The mineral occurs as radiating prismatic acicular crystals and radial spherules up to . Structure The crystal structure of bultfonteinite consists of strips of a4Si2O4sup>8+, that run along the 5.67 Å ''c''-axis, held together by Ca–O–Ca, Ca–F–Ca, Ca–H2O–Ca, and Ca–O–Si bonds. Silicon atoms occur in isolated tetrahedra and the calcium atoms have seven-fold coordination, derived from a triangular prism with a seventh atom present on one of the square faces. History In either 1903 or 1904, a miner discovered the first specimen of bultfonteinite on the 480-foot level of the Bultfontein mine in Kimberley, South Africa. The mineral occurred in a several-hundr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nesosilicates
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually considered a silicate mineral. Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from seawater. The frustules of dead diatoms are a major constituent of deep ocean sediment, and of diatomaceous earth. General structure A silicate mineral is generally an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natrolite
Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula . The type locality is Hohentwiel, Hegau, Germany. It was named natrolite by Martin Heinrich Klaproth in 1803. The name is derived from ''natron'' (), the Greek word for soda, in reference to the sodium content, and ''lithos'' (), meaning stone. Needle stone or needle-zeolite are other informal names, alluding to the common acicular habit of the crystals, which are often very slender and are aggregated in divergent tufts. The crystals are frequently epitaxial overgrowths of natrolite, mesolite, and gonnardite in various orders. Properties Larger crystals most commonly have the form of a square prism terminated by a low pyramid, the prism angle being nearly a right angle. The crystals are tetragonal in appearance, though actually orthorhombic. There are perfect cleavages parallel to the faces of the prism. The mineral also often occurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xonotlite
Xonotlite, or eakleite, is a mineral of general formula named by the German mineralogist Karl Friedrich August Rammelsberg in 1866. The name originates from its discovery locality, Tetela de Xonotla, Puebla, Mexico. Although it was discovered in 1866, it was first described in 1959. It is approved by the IMA, but it is a grandfathered species, meaning the name supposedly represents a valid species til this day. Properties Xonotlite is an ino-silicate with double dreier chains, of which several polytypes are known. The known polytypes are Ma2bc, Ma2b2c and M2a2bc. It is a mineral related to the tobermorite group. It can be colorless, gray, light gray, lemon white, or pink. It is transparent with a vitreous to silky luster. It leaves a white streak. Xonotlite is rated 6.5 on the Mohs scale of hardness. It crystallizes in the monoclinic - prismatic crystal system, with typically an acicular crystal form or habit, meaning it occurs as needle-like crystals. It is massive, meani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scawtite
Scawtite is a hydrous calcium silicate mineral with carbonate, formula: Ca7(Si3O9)2CO3·2H2O. It crystallizes in the monoclinic crystal system as thin plates or flat prisms. Scawtite was first described in 1929 for an occurrence at Scawt Hill in Northern Ireland. Scawtite occurs as in skarns and hydrothermal veins in limestone. Associated minerals include melilite, spurrite, tobermorite, thomsonite, larnite, grossular, bultfonteinite, calcite, analcime Analcime (; ) or analcite is a white, gray, or colorless tectosilicate mineral. Analcime consists of hydrated sodium aluminium silicate in cubic crystalline form. Its chemical formula is Na Al Si2 O6· H2O. Minor amounts of potassium and calciu ..., foshagite and hillebrandite. References {{silicate-mineral-stub Silicate minerals Monoclinic minerals Minerals in space group 12 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on Scratch hardness, scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German ''Calcit'', a term from the 19th century that came from the Latin word for Lime (material), lime, ''calx'' (genitive calcis) with the suffix "-ite" used to name minerals. It is thus etymologically related to chalk. When applied by archaeology, archaeologists and stone trade pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apophyllite
The name apophyllite refers to a specific group of phyllosilicates, a class of minerals. Originally, the group name referred to a specific mineral, but was redefined in 1978 to stand for a class of minerals of similar chemical makeup that comprise a solid solution series, and includes the members fluorapophyllite-(K), fluorapophyllite-(Na), hydroxyapophyllite-(K). The name apophyllite is derived from the Greek ἀποφυλλίζω ''apophylliso,'' meaning "it flakes off", a reference to this class's tendency to flake apart when heated, due to water loss. Exfoliation of apophyllite is also possible by treating it with acids or simply by rubbing it. These minerals are typically found as secondary minerals in vesicles in basalt or other volcanic rocks. A recent change (2008) in the nomenclature system used for this group was approved by the International Mineralogical Association, removing the prefixes from the species names and using suffixes to designate the species.Burke, E.A.J. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural History Museum, London
The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum and the Victoria and Albert Museum. The Natural History Museum's main frontage, however, is on Cromwell Road. The museum is home to life and earth science specimens comprising some 80 million items within five main collections: botany, entomology, mineralogy, palaeontology and zoology. The museum is a centre of research specialising in taxonomy, identification and conservation. Given the age of the institution, many of the collections have great historical as well as scientific value, such as specimens collected by Charles Darwin. The museum is particularly famous for its exhibition of dinosaur skeletons and ornate architecture—sometimes dubbed a ''cathedral of nature''—both exemplified by the large ''Diplodocus'' cast that domina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge University
, mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Scholars of the University of Cambridge , type = Public research university , endowment = £7.121 billion (including colleges) , budget = £2.308 billion (excluding colleges) , chancellor = The Lord Sainsbury of Turville , vice_chancellor = Anthony Freeling , students = 24,450 (2020) , undergrad = 12,850 (2020) , postgrad = 11,600 (2020) , city = Cambridge , country = England , campus_type = , sporting_affiliations = The Sporting Blue , colours = Cambridge Blue , website = , logo = University of Cambridge logo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Material (mineralogy)
In mineralogy, the type specimen, also known as type material, is a reference sample by which a mineral is defined.Dunn, p. 1269. Similar to the biology type methods, a mineral type specimen is a sample (or in some cases a group of samples) of a mineral to which the scientific name of that mineral is formally attached. In other words, a type specimen is an example that serves to anchor or centralize the defining features of that particular mineral. A mineral is a scientifically named set that includes some materials and excludes others, based on a detailed published description and on the provision of type specimens, which are usually available to scientists for examination in a major museum research collection, or similar institution. History Whereas the system of type specimens has long-existed in the biological sciences, this is not the case in mineralogy. The recentness of the practice means that sometimes no type material exists, even for minerals discovered as recently as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grandfather Clause
A grandfather clause, also known as grandfather policy, grandfathering, or grandfathered in, is a provision in which an old rule continues to apply to some existing situations while a new rule will apply to all future cases. Those exempt from the new rule are said to have grandfather rights or acquired rights, or to have been grandfathered in. Frequently, the exemption is limited, as it may extend for a set time, or it may be lost under certain circumstances; for example, a grandfathered power plant might be exempt from new, more restrictive pollution laws, but the exception may be revoked and the new rules would apply if the plant were expanded. Often, such a provision is used as a compromise or out of practicality, to allow new rules to be enacted without upsetting a well-established logistical or political situation. This extends the idea of a rule not being retroactively applied. Origin Southern United States The term originated in late nineteenth-century legislation and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Mineralogical Association
Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. The IMA is affiliated with the International Union of Geological Sciences (IUGS). The Association supports the activities of Commissions and Working Groups involved on certain aspects of mineralogical practice and facilitates interactions among mineralogists by sponsoring and organising meetings. In particular, the IMA holds its general meeting every four years. The next meeting is scheduled in 2022 in Lyon, France. Presidents The presidents of the IMA have been: * since 2021: Anhuai Lu ** Peking University *2018–2020: Patrick Cordier (born 1961) ** Université de Lille *2016–2018: Peter C. Burns ** University of Notre Dame *2014–2016: Sergey V. Krivovichev (born 1972) ** Saint Petersburg State University *2012–2014: Walter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
