The thermal decomposition processes of carbonate minerals are analyzed by comparison of the notions on chemical bonds in crystals and modern concepts on solid-phase reactions. It is shown that depending on the mechanism of thermal dissociation, the carbonate minerals most widespread in nature may be divided into two groups: first, CaCO3, SrCO3and BaCO3, characterized by decomposition temperatures close to the equilibrium values and undergoing recombination on cooling; and second, MgCO3, MnCO3, FeCO3and ZnCO3, with dissociation temperatures exceeding the equilibrium values by ∼ 250° and recombining only at high partial pressures of CO2(above 1000 ba