Abstract
Monohydrocalcite is rare mineral in geological settings. It found as biogenic calcium carbonate. In order to understand the stability relationships of calcium carbonate minerals under low temperature, we determined MHC solubility.The solubility of MHC increases with the temperature. MHC is stable at lower temperature. In addition, the solubility of MHC becomes lower than vaterite at the temperatures lower than 5 celcius degree. It indicates that MHC is possibly third stable calcium carbonate at lower temperature.