Despite the great interest in the PGE, the thermo-chemical basis of their geochemical properties
remains unclear. Thermodynamic data for PGE-minerals (PGM) are very limited, due probably to
experimental difficulties and very limited data on the activity-composition models and relevant phase
diagrams [21–28]. Assuming that the required thermodynamic data (enthalpy, entropy, Gibbs free
energy) of the reactants and physical/chemical conditions (P, T) are available, then the mineral Gibbs
free energy can be calculated [26–28]. This paper focuses on: (