Composition
Celsian is a barium feldspar with a chemical composition BaAl2Si2O8. It forms part of the feldspar group and belongs to the celsian-hyalophane series and the celsian-orthoclase series. It has some resemblance to anorthite, and it has four distinct polymorphs. The essential elements are Si,Al,O and Ba. Some common impurities in the mineral are Fe, Ti, Mg, K and Ca. Celsian is stable from room temperature up to 1590 °C ( Lin and Foster,1968). The most common trace elements are potassium and calcium, in an analysis of the approximate chemical composition of celsian the following wt% were found: • SiO2—35.1 • Al2O3---26.8 • BaO----35.8 • K2O-----2.3 Total:100.0 (Newham and Megaw,1960).
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