海水珍珠微结构棱柱层的新认识

棱柱层是珍珠层微结构中与珍珠质层明显不同的结构单元。运用XRD、IR显微镜和偏光显微镜对我国优劣海水珍珠层微结构——棱柱层进行微区测试研究，结果发现海水珍珠微结构棱柱层不是以往认为的仅由方解石组成，而是有各种形态的文石棱柱，文石与方解石共同组成的棱柱。珍珠质量与棱柱体层的厚度及空间分布有密切关系，而并非完全是以往认为的文石含量越高海水珍珠质量就越好。

A NEW UNDERSTANDING OF PRISM LAYER IN THE MICROSTRUCTURE OF SEA-CULTURED PEARL

The prism layer is obviously different from the parallel layer in sea-cultured pearl. XRD, optical microscopy and micros-IR have been applied to the crystallized layers of good and poor quality sea-cultured pearls from South China. The result shows that the prism layer is not composed of calcite. There are three types of prism in sea cultured pearl: calcite prism, aragonite prism, calcite + aragonite prism. Therefore, we have a new understanding of the biomineralization characteristics of prism layer in sea-cultured pearl. The result makes us renew the traditional explanation that the content of aragonite affects the quality of pearl. Because some sea prism pearl is composed almost completely of aragonite, but the quality of this kind of pearl is worst. The thickness and spatial distribution of prisms are one of the main factors which affect the quality of sea cultured pearl.