Chromium-aluminum mixing in garnet: A thermochemical study

The enthalpies of mixing of synthetic grossular (Ca₃Al₂Si₃O₁₂)-uvarovite (Ca₃Cr₂Si₃O₁₂) solid solutions have been determined by oxide melt calorimetry at 970 K. The results indicate that the solid solution exhibits a very small negative deviation from Raoult's law. In terms of the regular solution model a chromium-aluminum interaction parameter $\text{W}{}_{\mathrm{H}}{}^{\mathrm{Cr-Al}}$ of between 0 and ?1000 cal/gm atom is consistent with the data.