The principal investigator will continue a program to investigate the fundamental physicochemical properties of rock-forming minerals and mineral assemblages. He will measure free energies and enthalpies of formation of end-member silicates, free energies and enthalpies of mixing in solid solution series, mutual stabilities of important rock-forming mineral assemblages, and stabilities with respect to melting (especially under mixed volatile atmosphere, vapor-undersaturated conditions). Methods to be utilized include oxide melt solution calorimetry, displacement of experimentally determined phase equilibria, determination of cation-exchange equilibria, and both aqueous and other solubility measurements. This research should add significantly to the data base for important rock-forming minerals, both in thermodynamic and phase equilibrium terms, and lead to a better understanding of both mineral-mineral and mineral-liquid equilibria. These data are critical to geologists who use minerals and mineral assemblages to determine the conditions within the earth under which certain rocks form.
