Orthoclase
Orthoclase (also orthoclase ) is a very common mineral from the group of the feldspars and minerals class of silicates. It crystallizes in the monoclinic crystal system with the chemical formula K [ AlSi3O8 ] and developed either prismatic to tabular crystals or granular to massive aggregates in the different depending on the variety colors: white, gray, yellow, red and brown. Even colorless orthoclase are known.
Etymology and history
Named orthoclase in 1823 by August Breithaupt, for the " straight" or "right" and κλάσις classified for " break" named the mineral based on its good to perfect cleavage at right angles from the Greek words orthos ὀρθός.
Classification
Already in the now outdated but still in use 8th edition of the mineral classification by Strunz was one of the orthoclase to mineral class of " silicates and Germanates " and then to the Department of " framework silicates ( tectosilicates ) " where he along with Buddingtonit, celsian, Hyalophane, Kokchetavit, microcline, Paracelsian, Rubiklin, sanidine and slawsonite the independent " feldspar ( orthoclase slawsonite Buddingtonit - series) " formed with the system no. VIII/J.06.
The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the orthoclase also in the class of " silicates and Germanates " and there in the department of " framework silicates ( tectosilicates ) without zeolitic H2O" one. This division, however, is further subdivided according to the possible presence of other anions, so that the mineral is found according to its composition in the subsection " framework silicates ( tectosilicates ) without additional anions ", where it, along with adularia, anorthoclase, Buddingtonit, celsian, Hyalophane Kokchetavit, microcline, Monalbit, Rubiklin and sanidine feldspar with which the system no. 9.FA.30 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the orthoclase in the class of " silicates and Germanates " and then in the Department of: a " framework silicates Al- Si lattice ". Here he is with anorthoclase, celsian, Filatovit, Hyalophane, microcline, sanidine Rubiklin and in the group of "K (Na, Ba) - feldspars " with the system no. 76.01.01 found within the subdivision "With Al- Si lattice ".
Modifications and varieties
- Adularia ( adularia ) - pseudo- orthorhombic or pseudo-trigonal. From hydrothermal solutions crystallized, known mainly from the Alpine clefts Adula Alps. White, rare clear - transparent. The term is also used as a synonym for orthoclase in use. Paradoxit - red meat Adular
- Valencianit - milky turbid Adular
Education and Locations
Orthoclase is a typical rock forming mineral and is either formed in magmatic granite, pegmatite, rhyolite, syenite and trachyte or metamorphic in orthogneiss, migmatite and others.
Locations include in Hagen village in Germany, Elba Island in Italy, Itrongay in Madagascar, Strzegom in Poland, Loket and Karlovy Vary in the Czech Republic, California and South Dakota in the United States.
Crystal structure
Orthoclase crystallizes in the monoclinic space group C2 / m ( Raumgruppen-Nr. 12) with the lattice parameters a = 8.56 Å; b = 12.96 Å; c = 7.21 Å and 116.1 ° and β = 4 formula units per unit cell.
Use
Orthoclase is used in glass, ceramics and pharmaceutical industries. The variety Moonstone is used as a gemstone.