抄録
Calcium carbonate, CaCO_3, occurs in six different forms: three crystalline polymorphs (calcite, aragonite, and vaterite), two hydrate phases, and amorphous calcium carbonate (ACC). These polymorphs are important both in the earth science, as rock-forming minerals, and in chemical technology, as raw materials for industrial processes. Furthermore, the occurrence of CaCO_3 in living organisms has received considerable attention. Therefore formation process of these polymorphs has been extensively investigated, however our knowledge is far from complete. In the present paper, we review how the formation process of CaCO_3 has been described in literatures, including a discovery that crystallization occurs through non-classical mechanism such as stable prenucletaion cluster aggregation (Gebauer et al.: Science, 322, 1819), which give a new picture of the early stages of calcium carbonate growth.
