Research Progress on Biomineralization Mechanism of Freshwater Pearl

Calcium carbonate exists widely in many kinds of biominerals, and is one of the most widespread biominerals on the earth. The main component of the shell and pearl is calcium carbonate. In China, the majority of the freshwater pearls originated from Hyriopsis cumingii (Zhuji, Zhejiang Province) is with excellent quality and has outstanding pearly luster. The inorganic phase of this luster pearl is aragonite crystal and is regarded as aragonite pearl. Recently, the vaterite is observed in the freshwater cultured pearls, which is responsible for the lack luster and poor quality of the pearls. In the present paper, microstructure and property of the freshwater aragonite and vaterite pearl are introduced. In addition, in vitro growth of calcium carbonate crystal related to the pearl is reviewed. At last, the future research of nacre biomineralization is expected.