Pyroxene

Thermodynamic Properties of Pyroxene Solid Solutions with general formula (Na,Ca,Mg,Fe2+)[M2](Mg,Fe2+,Ti,Al,Fe3+)[M1](Al,Fe3+,Si)2[TET]O6 and structure type cpx, pig, or opx.

  1. Calculate Wt % oxides from mole fractions of endmembers.
  2. Calculate mole fractions of endmembers from Wt % oxides.
  3. Calculate thermodynamic properties from mole fractions of endmembers, T and P.
SiO2 TiO2 Al2O3 Fe2O3
Wt % oxides:
FeO MgO CaO Na2O
Wt % oxides:
Diopside
CaMgSi2O6		 Enstatite
Mg2Si2O6		 Hedenbergite
CaFeSi2O6		 Alumino-
buffonite
Ca(Ti,Mg)AlSiO6
Mole Fraction:
Buffonite
Ca(Ti,Fe)AlSiO6		 Esseneite
CaFeAlSiO6		 Jadeite
NaAlSi2O6
Mole Fraction:

Calculation of Thermodynamic Properties require specification of temperature (T) and Pressure (P)

Input a temperature (C): .
Input a pressure (bars): .
Action: results or the form.

Sack RO, Ghiorso MS (1994a) Thermodynamics of multicomponent pyroxenes I. Formulation of general model. Contributions to Mineralogy and Petrology 116, 277-286.

Sack RO, Ghiorso MS (1994b) Thermodynamics of multicomponent pyroxenes II. Applications to phase relations in the quadrilateral. Contributions to Mineralogy and Petrology 116, 287-300.

Sack RO, Ghiorso MS (1994c) Thermodynamics of multicomponent pyroxenes III. Calibration of Fe2+(Mg)-1, TiAl(MgSi)-1, TiFe3+(MgSi)-1, AlFe3+(MgSi)-1, NaAl(CaMg)-1, Al2(MgSi)-1, and Ca(Mg)-1 exchange reactions between pyroxenes and silicate melts. Contributions to Mineralogy and Petrology. 118, 271-296