Space group

Encyclopedia

In mathematics, physics and chemistry, a space group is the symmetry group of a configuration in space, usually in three dimensions. In three dimensions, there are 219 distinct types, or 230 if chiral copies are considered distinct. Space groups are also studied in dimensions other than 3 where they are sometimes called Bieberbach groups, and are discrete cocompact groups of isometries of an oriented Euclidean space. In crystallography, space groups are also called the crystallographic or Fedorov groups,

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Crystal system

Encyclopedia

In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals. Informally, two crystals are in the same crystal system if they have similar symmetries, although there are many exceptions to this. Crystal systems, crystal families, and lattice systems are similar but slightly different, and there is widespread confusion

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Crystallographic point group

Encyclopedia

In crystallography, a crystallographic point group is a set of symmetry operations, corresponding to one of the point groups in three dimensions, such that each operation would leave the structure of a crystal unchanged i.e. the same kinds of atoms would be placed in similar positions as before the transformation. For example, in a primitive cubic crystal system, a rotation of

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Hermann–Mauguin notation

Encyclopedia

In geometry, Hermann–Mauguin notation is used to represent the symmetry elements in point groups, plane groups and space groups. It is named after the German crystallographer Carl Hermann (who introduced it in 1928) and the French mineralogist Charles-Victor Mauguin (who modified it in 1931). This notation is sometimes called international notation, because it was adopted as standard by the International Tables For Crystallography since their first edition in 1935. The Hermann–Mauguin

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Nickel–Strunz classification

Encyclopedia

Nickel–Strunz classification is a scheme for categorizing minerals based upon their chemical composition, introduced by German mineralogist Karl Hugo Strunz (24 February 1910 – 19 April 2006) in his Mineralogische Tabellen (1941). The 4th and the 5th edition was also edited by Christel Tennyson (1966). It was followed by A.S. Povarennykh with a modified classification (1966 in Russian, 1972 in English). As curator of the Mineralogical

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Monoclinic crystal system

Encyclopedia

In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a rectangular prism with a parallelogram as its base. Hence two pairs of vectors are perpendicular (meet at right angles), while the third pair makes an angle

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Chemical formula

Encyclopedia

A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not

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Daund taluka

Encyclopedia

Daund taluka दौंड तालुका Taluka Location of Daund in Pune district in Maharashtra Coordinates: 18.4631°N 74.5789°ECoordinates: 18.4631°N 74.5789°E Country  India State Maharashtra District Pune district Headquarters Daund Government  • Lok Sabha constituency supriya sule  • Assembly constituency Rahul shubhash kul Area  • Taluka 1,290 km2(500 sq mi) Population  (2011)  • Taluka 382,535  • Density 300/km2 (770/sq mi)  • Urban 56,436 Daund taluka is a taluka or subdivision of Pune district of the state of Maharashtra in India. The town

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List of Maratha dynasties and states

Encyclopedia

This is a partial list of Maratha dynasties and Maratha princely states. Contents   1Historical Maratha clans from the original dynasty 2Maratha Princely States 2.1The Maratha Salute state and Head of State by precedence 2.2Non-salute states 2.3States Annexed by the British under the Doctrine of Lapse 3See also 4References 5External links and sources Historical Maratha clans from the

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Apparent place

Encyclopedia

The apparent place of an object is its position in space as seen by an observer. Because of physical and geometrical effects it may differ from the “true” or “geometric” position. Contents   1Astronomy 1.1Position of a star 1.2Solar System objects 1.3Topocentric position 2See also 3References 4External links Astronomy In astronomy, a distinction is made between the mean position, apparent position and topocentric position of

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