流沙湾海水养殖劣质珍珠微观结构研究

Microstructure of poor-quality pearls cultured in seawater from Liushawan

为了探讨流沙湾海水养殖珍珠出现杂质的原因,利用扫描电子显微镜（SEM）对劣质珍珠外表面、纵截面及内表面的微观结构进行系统的观察研究；利用傅里叶变换红外光谱仪（FTIR）对劣质珍珠各层物质的结构和成分进行分析.结果表明：劣质珍珠层外表面凸凹不平、生长机理纹杂乱无章及文石晶体有序排列程度低,是造成珍珠质量差的重要原因之一.劣质珍珠的珍珠层厚度为130 ～240μm,其中珍珠质层厚度为120 ～ 220 μm,棱柱层的厚度为15 ～50 μm,杂质层厚度不均匀.珍珠质层是流沙湾劣质珍珠珠层的主要成分.珍珠杂质层呈黑色或者灰褐色,这也是劣质珍珠质量差的重要原因.珍珠杂质的红外光谱分析表明其主要为蛋白质类有机物质,并结合少量的碳酸钙成分.

In order to explore the cause of the existence of impurity in poor-quality pearls cultured in seawater from Liushawan,scanning electron microscopy （SEM） was used to observe the microstructure of the surface,the longitudinal section and the internal surface of poor-quality pearls.FTIR spectra of each layer of poor-quality pearls were studied to analyze the structure and compositions of the poor-quality pearls.The results show that the surface of the poor-quality pearl is scraggly,the growth mechanism grain is disorderly and unsystematic,and the aragonite crystals are orderly arranged with low degree of crystallinity.This is one of the important reasons for forming poor quality pearls.The thickness of the nacre in poor-quality pearls is between 130 to 240 μm.The thickness of the nacreous layer is between 120 to 220 μm,and the prismatic layer is between 15 to 50 μm,while the thickness of the impurity layer is nonuniform.The nacreous layer is the main constituent part of the poor-quality pearls from Liushawan.The impurity layer is in black or beige,which is another important reason for forming poor-quality pearls.The FTIR spectra of the impurity in poor-quality pearl shows that the main composition is the organic protein combined with a small amount of calcium carbonate.