Activity-composition relationships garnets

Hensen B. I, Schmid R., and Wood B. J. (1975). Activity-composition relationship for pyrope-grossular garnet. Contrib. Mineral Petrol, 54 161-166. 

Koziol A. M. (1990). Activity-composition relationship of binary Ca-Fe and Ca-Mn garnets determined by reversed, displaced equilibrium experiments. Amer. Mineral, 75 319-327. 

Koziol AM (1996) Quaternary (Ca-Fe-Mg-Mn) garnet Displaced equilibrium experiments and implications for current garnet mixing models. Eur J Mineral 8 453-460 Koziol AM, Newton RC (1989) Grossular activity-composition relationships in ternary garnets determined by reversed displaced-equilibrium experiments. Contrib Mineral Petrol 103 423-433 Kretz R (1983) Symbols for rock-forming minerals. Am Mineral 68 277-279... 

The first object of this paper is to review the general approach to determining activity-composition relationships for binary and ternary solid solutions. The latter part of the paper will be devoted to some new and recently published results on garnet and alimiinous clinopyroxene solutions. 

The principal problem associated with the determination of the mixing properties of aluminosilicate garnets is that most of the solutions involved are stable only at high pressures. The apparatus used in experimental studies at these pressures does not, of course, enable as accurate a control of the intensive variables as is possible at 1 atmosphere. Nevertheless, activity-composition relationships determined at high pressures need not necessarily have extremely large uncertainties provided that the equilibria used to fix activities are carefully chosen. 

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