Internally-Consistent Thermodynamic Data for Minerals in the System Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3-SiO2-TiO2-H2O-CO2

Abstract

Internally consistent standard state thermodynamic data are presented for 67 minerals in the system Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3-SiO2-TiO2-H2O-CO2. The method of mathematical programming was used to achieve consistency of derived properties with phase equilibrium, calorimetric, and volumetric data, utilizing equations that account for the thermodynamic consequences of first and second order phase transitions, and temperature-dependent disorder. Tabulated properties are in good agreement with thermophysical data, as well as being consistent with the bulk of phase equilibrium data obtained in solubility studies, weight change experiments, and reversals involving both single and mixed volatile species. The reliability of the thermodynamic data set is documented by extensive comparisons (Figs. 4–45) between computed equilibria and phase equilibrium data. The high degree of consistency obtained with these diverse experimental data gives confidence that the refined thermodynamic properties should allow accurate prediction of phase relationships among stoichiometric minerals in complex chemical systems, and provide a reasonable basis from which activity models for minerals may be derived.