A series of complex oxides have, along the years, raised interest in the field of Martian mineralogy. This includes compounds of the Jarosite, Apatite and Jahnsite large groups of minerals. Whereas some of them, typically F- and Cl-apatites have been identified on the red planet, the presence of some other phases like Jarosites and more recently Jahnsites have been suspected to occur on Mars without actual proofs of their presence. 

Whether for confirming or invalidating the possible presence of such oxide phases on the surface of Mars, or for better assessing their eventual evolution in the Martian atmosphere and surface conditions, it is primordial to have access to thermodynamic data – as much reliable as possible – yet sometimes scarcely available. Thus, in this long run work along the years, we have launched synthesis procedures with the view to prepare relevant compositions of these three families of minerals ore relevance to Mars mineralogy, and explored their thermodynamics through oxide-melt solution calorimetry when possible, and via the ThermAP (Applied Predictive Thermodynamics) simplified predictive approach. 

In this presentation, the main milestones and findings of this research will be reminded, and the main thermodynamic trends will be highlighted with regards to Jarosites, Apatites and Jahnsites.