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Bararite is a natural form of ammonium fluorosilicate (also known as hexafluorosilicate or fluosilicate). It has chemical formula (NH4)2SiF6 and trigonal crystal structure. This mineral was once classified as part of cryptohalite. Bararite is named after the place where it was first described, Barari, India.〔Palache, C., Berman, H., and Frondel, C. (1951) Dana’s System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, etc. John Wiley and Sons, Inc., New York, 7th edition.〕 It is found at the fumaroles of volcanoes (Vesuvius, Italy), over burning coal seams (Barari, India), and in burning piles of anthracite (Pennsylvania, U.S.). It is a sublimation product that forms with cryptohalite, sal ammoniac, and native sulfur.〔Anthony, J.W., Bideaux, R.A., Bladh, K.W., and Nichols, M.C. (1997) Handbook of Mineralogy, Volume III: Halides, Hydroxides, Oxides. Mineral Data Publishing, Tucson. *(link to bararite ) *(link to cryptohalite )〕 ==History== A. Scacchi first discovered cryptohalite in 1873.〔 It appeared in a volcanic sublimate from the Vesuvian eruption of 1850. In 1926, W.A.K. Christie reported his own chemical study. A microscope was used to pick out enough material for analysis. Distilling with sodium hydroxide (NaOH) produced ammonia (NH3). The anions of hexafluorosilicic acid (H2SiF6) precipitated as potassium fluorosilicate (K2SiF6). Barium sulfate (BaSO4) was thrown into the filtrate, and then calcium fluoride (CaF2). Christie found 20.43% (NH4)+ and 78.87% (SiF6)2−.〔Christie, W.A.K. (1926) An Occurrence of Cryptohalite (Ammonium Fluosilicate). Records of the Geological Survey of India, 59, 233.〕 Bararite is named after Barari, a locality in India. This was where the species was first completely described. Earlier, bararite was recognized as part of mixtures with cryptohalite.〔 However, it did not receive its own name until 1951.〔〔Fleischer, M. (1952) ("New Mineral Names" ). American Mineralogist, 37, 359–362.〕 The East Indian Coal Company provided the sample that Christie used to evaluate bararite.〔 Bararite has not received a quantitative chemical analysis in its natural form.〔 Christie received far too little for more than ''qualitative'' analysis through microchemistry. He utilized F. Emich’s methods with capillary tube centrifuges.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bararite」の詳細全文を読む スポンサード リンク
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