This study is a preliminary work on the description and the modeling of mechanisms potentially causing discrepancies between experimental data and thermodynamic calculation performed on carbonate equilibrium at high temperature. A better understanding of dolomite dissolution/precipitation processes that occur during its equilibration is important for investigations of high-level radioactive waste disposal or Carbon and Capture Storage (CCS). The first results demonstrated the fast dolomite equilibration in solution (within 12 days) and the good agreement between experimental and thermodynamic calculations at 25 °C for dolomite and calcite-dolomite systems whereas discrepancies are observed at higher temperature (80 °C). As shown from cathodoluminescence photomicrographs, one of the expected mechanisms causing those differences is the incorporation of trace elements such as Mg, Mn or Ba found in natural systems.