淡水养殖珍珠表面瓷质层的微形貌特征

Microscopic Morphology of Porcelaneous Layers on Surface of Freshwater Cultured Pearls

采用扫描电子显微镜对中国浙江诸暨三角帆蚌养殖珍珠表面特别是无珍珠光泽的瓷质层的微形貌进行了研究,并采用X射线粉晶衍射对瓷质层进行了物相鉴定。结果表明,珍珠表面的瓷质层由两种形貌完全不同的六方碳钙石组成。其一,六方碳钙石晶体呈不规则一向延长的薄片状,晶体的长径为4.4～7.1μm,短径为1.4～2.6μm,长、短径比为2.3～3.7∶1;其二,晶体明显呈纤维柱状,每个纤维柱似由更细的纤维聚合而成,纤维柱的长径为7.0～11.6μm,短径为0.9～1.5μm,长、短径比为7.5～9.1∶1。瓷质层中六方碳钙石的形貌与正常珍珠层中文石的形貌明显不同。

The Scanning electron microscopy is used to study the morphological features of porcelaneous layers on surface of freshwater cultured pearls from Zhuji, Zhejiang Province, and the calcium carbonate polymorph of porcelaneous layers is identified by X-ray powder diffraction. It can be concluded that the porcelaneous layers are composed of vaterites with two kinds of microscopic morphology. The vaterites occur as elongated thin tablets with dimension of 4.4~7.1 μm×1.4~2.6 μm and length/width ratio of 2.3~3.7∶1, or as elongated fibers with dimension of 7.0~11.6 μm×0.9~1.5 μm and length/width ratio of 7.5~9.1∶1. These two kinds of microscopic morphology of vaterite crystals in porcelaneous layers of the pearls are clearly different from that of aragonites in nacreous layers.