Phase transformation-induced Mg isotope fractionation in Mg-mediated CaCO3 mineralization

The biomineralization of CaCO3 often involves the transformation of amorphous precursors into crystalline phases, which is regulated by various proteins and inorganic ions such as Mg2+ ions. While the effects of Mg2+ ions on the polymorph and shape of the crystalline CaCO3 have been observed and studied, the interplay between Mg2+ ions and CaCO3 during the mineralization remains unclear. This work focuses on the mechanism of Mg2+ ion-regulated mineralization of CaCO3. By tracing the Mg isotope fractionation, the different mineralization pathways of CaCO3 under different Mg2+ ion concentrations had been clarified. Detailed regulatory role of Mg2+ ions at the different stages of mineralization had been proposed through combining the fractionation data with the analyses of the CaCO3 polymorph and shape evolution. These results provide a clear view of the Mg-mediated crystallization process of amorphous CaCO3, which can be used to finely control the phase of the crystalline products according to different needs.

Automated summary

This study investigates the mechanism of Mg2+ ion-regulated mineralization of CaCO3 by tracing Mg isotope fractionation. The different mineralization pathways of CaCO3 under different Mg2+ ion concentrations are clarified, and the detailed regulatory role of Mg2+ ions at different stages of mineralization is proposed. These results provide important insights for finely controlling the phase of crystalline products.