Claim: Monohydrocalcite forms via a Mg-rich ACC quickly and transforms to monohydrocalcite using dissolution and reprecipitation.
Evidence: Monohydrocalcite forms via a Mg-rich amorphous calcium carbonate (ACC) precursor. This Mg-rich ACC forms rapidly (seconds) and then transforms to monohydrocalcite via dissolution and reprecipitation, with monohydrocalcite forming via a nucleation-controlled reaction like spherulitic growth.