Enthalpies of Formation at 970 k of Compounds in the System MgO-Al2O3-SiO2 from High Temperature Solution Calorimetry.

摘要

The enthalpies of solution of petrologically important phases in the system MgO-Al2O3-SiO2 were measured in a melt of composition 2PbO.B2O3 at 970 + or - 2 K. The substances investigated included synthetic and natural (meteoritic) enstatite (MgSiO3), synthetic aluminous enstatite (MgSiO30.9Al2O30.1), synthetic and natural cordierite (Mg2Al4Si5O18), synthetic and natural sapphirine (approx. 7MgO.9Al2O3.3SiO2), synthetic spinel (MgAl2O4), natural sillimanite (Al2SiO5), synthetic forsterite (Mg2SiO4), synthetic pyrope (Mg3Al2Si3O12), natural quartz (SiO2), synthetic periclase (MgO) and corumdum (Al2O3). Improvement in standardization of the calorimeter solvent made possible greater precision in this study than obtainable in former work in this laboratory on some of the same substances. (Author)