The Ternary System CaO—MnO—SiO 2

This is the authors' abstract. We don't add key points for this paper.

Phase equilibrium data resulting from quenching experiments are presented for the ternary system CaO‐MnO‐SiO 2 . An atmosphere of controlled oxygen pressure having P o2 , ≅ 10 −6 atm at 1555°C was used to maintain the manganese in the divalent state. The ternary liquidus surface is largely one of low‐lying liquidus temperatures. Three ternary liquidus minima dominate this surface. These have the following compositions (in weight percent CaO, MnO, and SiO 2 ): (a) 5.0, 48.4, and 46.6%, (b) 17.5, 45.0, and 37.5%, and (c) 15.0, 53.0, and 32.0%. Temperatures measured at these points are (a) 1265° C, (b) 1195°C, and (c) 1204°C. Isofracts of the quenched glasses are presented. Crystallization paths of ternary mixtures are represented by a series of fractionation curves and selected isothermal planes. Partition of manganese between coexisting pairs of crystalline phases (e.g., meta‐silicate, olivine, and (Ca,Mn)O solid solutions) favors concentration of manganese in the more basic phase. Subsolidus equilibria involving these phases and also Ca 3 Si 2 O 7 and Ca 3 SiO 5 are discussed. Ca 3 Si 2 O 7 and Ca 3 SiO 6 do not admit any appreciable amounts of Mn ++ into their lattices.