日本马氏贝珍珠化学组成的同步辐射X射线荧光光谱分析

Chemical composition analysis of Pinctada martensii pearls from Japan by synchrotron radiation micro X-ray fluorescence

采用同步辐射微区X射线荧光光谱技术,探测古铜色日本马氏贝珍珠剖面(珠核与珍珠层)的元素分布。测试结果表明,样品中主要含有Ca、Sr、Ba等3种碱土金属元素,Mn、Fe、Cu、Zn等4种3d过渡金属元素以及稀土元素,各元素在珍珠中表现出一定的空间分布规律:珠核表面稀土元素浓度最高,珍珠层和珠核的稀土元素浓度大致相当;Mn和Fe元素浓度自珠核浅表层向珠核表面有降低趋势;珍珠层内Mn和Fe元素浓度都出现大幅降低现象,且是在相同的圈层降低,显示其具有一定正相关性,推测二者大幅降低的圈层是平行层和棱柱层的分界,且Mn元素主要赋存于棱柱层;Ca与Sr、Ba元素的分布具有负相关性。

The chemical compositions and component distributions of Pinctada martensii pearls from Japan were investigated by synchrotron X-ray fluorescence spectrum. The results clearly show that these pearls contain Ca, Sr, Ba alkaline-earth metal elements, Mn, Fe, Cu, and Zn 3d transition metal elements and rare earth elements. In pearls, these elements present some distributions in space： the nucleus surface has the highest concentrations of rare earth elements and the concentrations of rare earth elements in the nacre and nucleus are roughly equal; in the nucleus there exists decreasing tendency of elements Mn and Fe from the superficial part to the surface; both Mn and Fe exhibit sharp fall in the same circle of the nacre, showing a certain correlation, and the place of sharp fall seems to be the dividing line of nacreous layer and prismatic layer; element Mn mainly exists in prismatic layer; the distributions of elements Sr and Ba show negative relationship with element Ca.