The polymorphic structures of three anhydrous crystalline CaCO 3 forms produced via the carbonation of cementitious materials and biomineralization (calcite, aragonite, and vaterite) are well-known compounds. Calcite is the most thermodynamically stable mineral among these phases, followed by aragonite, while vaterite is the most thermodynamically unstable. Consequently, various metastable phases of vaterite give rise to a range of polymorphic structures depending on the production route and mineralization environment. Understanding the formation mechanism of carbonate minerals, including vaterite, is crucial, as it represents an important route for fixing carbon dioxide into carbonate compounds in cementitious materials and biomineralization.