Thermodynamic properties of wollastonite, pseudowollastonite and CaSiO (sub 3) glass and liquid

Available thermodynamic data for wollastonite, pseudowollastonite and CaSiO (sub 3) glass and liquid have been reviewed and complemented to obtain a consistent set of thermodynamic properties: heat capacities, entropies, and temperatures and enthalpies of transition and fusion. Drop-calorimetry experiments for wollastonite between 800 and 1350 K show a first-order phase transition at 995 K with a small enthalpy of transition of 200 J/mol. From low-temperature C (sub p) measurements between 10 and 370 K for CaSiO (sub 3) glass, the absolute and configurational entropies of the amorphous phases have been determined. The differences between the properties of wollastonite and pseudowollastonite are greater than suggested by current polyhedral modeling of the heat capacity.