Phlogopite reacts to form orthorhombic kalsilite, leucite, forsterite and fluid (H2O) at 1012 ?? 7??C, 400 bars pressure, and 905 ?? 5??C at 100 bars pressure. The heat of reaction is 39 ?? 4 kcal compared to 44 ?? 6kcal for the reaction of annite to form orthorhombic kalsilite, leueite, fayalite and fluid (H2O). The results are consistent with earlier experiments, but not with the interpretations of those experiments. ?? 1967.
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A low pressure investigation of the stability of phlogopite