Solubility of rhodochrosite (MnCO3) in water and seawater

The solubility product of rhodochrosite (MnCO₃) was measured in seawater, deionized water and dilute NaCl solutions. The solubility product extrapolated to infinite dilution at 25.0 C was (2.60 ± 0.07)× 10^?11. The stoichiometric solubility product measured in seawater of 34.27%. salinity was (3.24 ± 0.23) × 10^?9 at 25.0 C and (2.28 ± 0.24) × 10^?9 at 3.3 C. The stoichiometric solubility product is in good agreement with the value calculated from an ion association model. The enthalpy of the reaction is in fair agreement with the estimated value.