| 词条 | Langbeinite |
| 释义 |
| name = Langbeinite | boxwidth = | boxbgcolor = | image = File:History museum of Truskavets 086.jpg | imagesize = 260px | alt = | caption = Langbeinite in the History Museum, Truskavets | category = Sulfate mineral | formula = K2Mg2(SO4)3 | molweight = | strunz = 7.AC.10 | dana = | system = Cubic | class = Tetartoidal (23) (same H-M symbol) | symmetry = P213 | unit cell = a = 9.92 Å; Z = 4 | color = Colorless with pale shades of yellow, pink, red, green, gray | colour = | habit = As nodules, disseminated grains, bedded massive | twinning = | cleavage = | fracture = Conchoidal | tenacity = Brittle | mohs = 3.5 - 4 | luster = Vitreous | streak = | diaphaneity = Transparent | gravity = 2.83 | density = | polish = | opticalprop = Isotropic | refractive = n = 1.5329–1.5347 | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = Slowly dissolves in water | impurities = | alteration = | other = Piezoelectric | references = [1][2][3] }}Langbeinite is a potassium magnesium sulfate mineral with the chemical formula K2Mg2(SO4)3. Langbeinite crystallizes in the isometric-tetartoidal system as transparent colorless or white with pale tints of yellow to green and violet crystalline masses. It has a vitreous luster. The Mohs hardness is 3.5 to 4 and the specific gravity is 2.83. The crystals are piezoelectric.[1] The mineral is an ore of potassium and occurs in marine evaporite deposits in association with carnallite, halite and sylvite.[1] It was first described in 1891 for an occurrence in Wilhelmshall, Halberstadt, Saxony-Anhalt, Germany, and named for A. Langbein of Leopoldshall, Germany.[1][2] Langbeinite gives its name to the langbeinites, a family of substances with the same cubic structure, a tetrahedral anion, and large and small cations. Related substances include hydrated salts leonite (K2Mg(SO4)2·4H2O) and picromerite (K2Mg(SO4)2·6H2O). References1. ^1 2 3 Handbook of Mineralogy {{sulfate-mineral-stub}}2. ^1 Mindat with location data 3. ^Webmineral data 3 : Sulfate minerals|Evaporite|Cubic minerals |
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