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Chrysotile Asbestos
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in the United StatesOccupational Safety and Health Administration, U.S. Department of Labor (2007)29 C.F.R. 1910.1001 Appendix J. and a similar proportion in other countries.Institut national de recherche sur la sécurité (1997).Amiante." ''Fiches toxicologiques.'' n° 167. (in French) It is a soft, fibrous silicate mineral in the serpentine subgroup of phyllosilicates; as such, it is distinct from other asbestiform minerals in the amphibole group. Its idealized chemical formula is Mg( Si O)( OH). The material has physical properties which make it desirable for inclusion in building materials, but poses serious health risks when dispersed into air and inhaled. Polytypes Three polytypes of chrysotile are known. These are very difficult to distinguish in hand specimens, and polarized light microscopy must normally be used. Some older publicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllosilicates
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, the crystalline forms of silica (silicon dioxide, ) are usually considered to be Silicate mineral#Tectosilicates, tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). Silica is found in nature as the mineral quartz, and its polymorphism (materials science), 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 carbonate–silicate cycle, geologic cycle. For example, a type of plankton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polytype
In crystallography, polymorphism is the phenomenon where a compound or element can crystallize into more than one crystal structure. The preceding definition has evolved over many years and is still under discussion today. Discussion of the defining characteristics of polymorphism involves distinguishing among types of transitions and structural changes occurring in polymorphism versus those in other phenomena. Overview Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure." Additionally, Walter McCrone described the phases in polymorphic matter as "different in crystal structure but identical in the liquid or vapor states." McCrone also define ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthorhombic
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular Prism (geometry), prism with a rectangular Base (geometry), base (''a'' by ''b'') and height (''c''), such that ''a'', ''b'', and ''c'' are distinct. All three bases intersect at 90° angles, so the three lattice vectors remain mutually orthogonal. Bravais lattices There are four orthorhombic Bravais lattices: primitive orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic. For the base-centered orthorhombic lattice, the primitive cell has the shape of a right rhombic prism;See , row oC, column Primitive, where the cell parameters are given as a1 = a2, α = β = 90° it can be constructed because the two-dimensional centered rectangular base layer can also be descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukraine to the east, Slovakia and the Czech Republic to the south, and Germany to the west. The territory has a varied landscape, diverse ecosystems, and a temperate climate. Poland is composed of Voivodeships of Poland, sixteen voivodeships and is the fifth most populous member state of the European Union (EU), with over 38 million people, and the List of European countries by area, fifth largest EU country by area, covering . The capital and List of cities and towns in Poland, largest city is Warsaw; other major cities include Kraków, Wrocław, Łódź, Poznań, and Gdańsk. Prehistory and protohistory of Poland, Prehistoric human activity on Polish soil dates to the Lower Paleolithic, with continuous settlement since the end of the Last Gla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Silesia
Lower Silesia ( ; ; ; ; ; ; ; ) is a historical and geographical region mostly located in Poland with small portions in the Czech Republic and Germany. It is the western part of the region of Silesia. Its largest city is Wrocław. The first state to have a stable hold over the territory of what will be considered Lower Silesia was the short-lived Great Moravia in the 9th century. Afterwards, in the Middle Ages, Lower Silesia was part of Piast-ruled Poland. It was one of the leading regions of Poland, and its capital Wrocław was one of the main cities of the Polish Kingdom. Lower Silesia emerged as a distinctive region during the fragmentation of Poland in 1172, when the Duchies of Opole and Racibórz, considered Upper Silesia since, were formed of the eastern part of the Duchy of Silesia, and the remaining, western part was since considered Lower Silesia. During the , German settlers were invited to settle in the region, which until then had a Polish majority. As a result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Złoty Stok
Złoty Stok (, , "''Richstone''") is a town in Ząbkowice Śląskie County, Lower Silesian Voivodeship, in south-western Poland. It is situated on the border with the Czech Republic, adjoining the Czech village Bílá Voda. It is the seat of the administrative district (gmina) called Gmina Złoty Stok, and lies approximately south of Ząbkowice Śląskie and south of the regional capital Wrocław. History The name ''Złoty Stok'' means "golden hillside" in Polish and is a reference to the fact that a gold deposit was mined here in the Middle Ages. Its Czech name is applied to the neighbouring mountain range, the Rychleby Mountains (). The corresponding Polish name is ''Góry Złote'' (Golden Mountains). This range is part of the eastern Sudetes. The area became part of the emerging Polish state in the 10th century under first historic ruler Mieszko I of Poland of the Piast dynasty, and after the fragmentation of Poland it was located in the duchies of Silesia, Świdnica- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoclinic
In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a parallelogram prism (geometry), prism. Hence two pairs of vectors are perpendicular (meet at right angles), while the third pair makes an angle other than 90°. Bravais lattices Two monoclinic Bravais lattices exist: the primitive monoclinic and the base-centered monoclinic. For the base-centered monoclinic lattice, the primitive cell has the shape of an oblique rhombic prism;See , row mC, column Primitive, where the cell parameters are given as a1 = a2, α = β it can be constructed because the two-dimensional centered rectangular base layer can also be described with primitive rhombic axes. The length a of the primitive cell below equals \frac \sqrt of the conventional cell above. Crystal class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unit Cell
In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector In mathematics, a unit vector in a normed vector space is a Vector (mathematics and physics), vector (often a vector (geometry), spatial vector) of Norm (mathematics), length 1. A unit vector is often denoted by a lowercase letter with a circumfle ..., for example) does not necessarily have unit size, or even a particular size at all. Rather, the primitive cell is the closest analogy to a unit vector, since it has a determined size for a given lattice and is the basic building block from which larger cells are constructed. The concept is used particularly in describing crystal structure in two and three dimensions, though it makes sense in all dimensions. A lattice can be characterized by the geometry of its unit cell, which is a section of the tiling (a parallelogra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mindat
Mindat may refer to: Places * Mindat District, a district in Chin State, Myanmar (Burma), consisting of two townships and many villages ** Mindat Township, Myanmar *** Mindat, Chin State, a town in Chin State, Myanmar, administrative seat of Mindat Township Other uses * Mindat, alternative name for the Kʼchò language in Myanmar * Mindat Min, a Burmese prince * Mindat.org, an online mineralogy database {{dab, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Locality (geology)
Type locality, also called type area, is the locality where a particular rock type, stratigraphic unit or mineral species is first identified. If the stratigraphic unit in a locality is layered, it is called a stratotype, whereas the standard of reference for unlayered rocks is the type locality. The concept is similar to type site in archaeology. Examples of geological type localities Rocks and minerals * Aragonite: Molina de Aragón, Guadalajara, Spain * Autunite: Autun, France * Benmoreite: Ben More (Mull), Scotland * Blairmorite: Blairmore, Alberta, Canada * Boninite: Bonin Islands, Japan * Comendite: Comende, San Pietro Island, Sardinia * Cummingtonite: Cummington, Massachusetts * Dunite: Dun Mountain, New Zealand * Essexite: Essex County, Massachusetts, US * Fayalite: Horta, Fayal Island, Azores, Portugal * Harzburgite: Bad Harzburg, Germany * Icelandite: Thingmuli (Þingmúli), Iceland * Ijolite: Iivaara, Kuusamo, Finland * Kimberlite: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal System
In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices (an infinite array of discrete points). Space groups (symmetry groups of a configuration in space) are classified into crystal systems according to their point groups, and into lattice systems according to their Bravais lattices. Crystal systems that have space groups assigned to a common lattice system are combined into a crystal family. The seven crystal systems are ''triclinic'', ''monoclinic'', ''orthorhombic'', ''tetragonal'', ''trigonal'', ''hexagonal'', and ''cubic''. Informally, two crystals are in the same crystal system if they have similar symmetries (though there are many exceptions). Classifications Crystals can be classified in three ways: lattice systems, crystal systems and crystal families. The various classifications are often confused: in particular the trigonal crystal system i ... [...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 last meeting was scheduled in 2022 in Lyon, France. Presidents The presidents of the IMA have been: * since 2024: Eiji Ohtani ** Tohoku University * 2022–2024: Hans-Peter Schertl ** Bochum University * 2020–2022: Anhuai Lu ** Peking University *2018–2020: Patrick Cordier ** Université de Lille *2016–2018: Peter C. Burns ** University of Notre Dame *2014–2016 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
