Microstructure of Hyriopsis Schlegeli Shells and Its Pearls

By means of gemmological microscope,polarizing microscope and scanning electron microscope,the special surface characters and microstructure of the Hyriopsis schlegeli shells and its pearls from Fuzhou,Jiangxi Province,are observed.The results indicate that the main characters of the vertical section of the shells are periostracum—prismatic layer—nacreous layer.Some of the shells behave as a multilayer intricate complex growing structure,which could be due to the discontinuous growing of the shells.The structure of nacreous layer is characterized as a form of "brick wall",laying the "bricks" with organic matter and aragonite slices.To be noticed that the spiral grains on the surface of nacreous layer of Hyriopsis schlegeli shells and its pearls are rarely found in other fresh water cultured pearls.When scanning the spiral grains on the special surface by using scanning electron microscope,it is found that a single spiral line is constituted by semi-closed circles,accordingly,it could be a variant form of layered deposits.By means of SEM, it is found that the characteristic structures of some nucleated pearls behave from inner to outside:nucleus—initial growth layer—nacreous layer.The aragonites in the initial growth layer deposit randomly in the form of irregular spherulites,which indicates the character of fast growth.