▎ 摘　　要

The mineralization dynamics of calcium carbonate is investigated under highly supersaturated conditions using graphene liquid cell transmission electron microscopy. We demonstrate that the mineralization process has three steps: nucleation, diffusion-limited growth, and Ostwald ripening/coalescence. In addition, we show that the polymorphs precipitate in a specific order, from metastable aragonite to stable calcite, thus proving Ostwald's rule of stages. In highly supersaturated solutions, the aragonite phase crystallizes in a stable manner, in addition to the calcite phase.