Speciation of Mg associated with monohydrocalcite

Abstract

Monohydrocalcite (MHC) is one of the hydrous Ca carbonates, and rare mineral in geological settings. We revealed the formation condition of MHC by synthesis experiments. Also we suggested that MHC require the paragenesis of hydrous Mg carbonates. In this study, we conducted the synthesis experiments MHC and amorphous Mg carbonates (AMC) and XAFS measurements to clarify the speciation of Mg associated with MHC.As a result of XANES measurements and pattern fitting, we suggested that MHC have two type of Mg, as the mixture of AMC at outside of MHC and Mg inside of MHC like Mg of aragonite.