和田玉糖玉的致色机理研究

采用X射线粉晶衍射(XRD)、 激光剥蚀等离子体质谱(ICP-MS)、 拉曼光谱(RAMAN)和高分辨率透射电子显微镜(HRTEM)对和田玉糖玉的致色机理进行研究。结果显示，糖玉的主要矿物成分为透闪石，化学成分中的Fe含量和糖玉黄褐色色调有正相关关系，颜色越深Fe的含量越高，Fe在糖玉中以独立铁质矿物的赋存形式分布于透闪石的颗粒间、 微裂隙中。铁质矿物由于其含量低、 粒度细小，本文设计实验对其进行富集后进行测试。将铁质矿物富集后的样品进行透射电镜测试，铁质矿物呈云状集合体，电子花样衍射图显示其矿物为针铁矿。因此，针铁矿分布于透闪石颗粒间、 微裂隙中致使糖玉呈现黄褐色。拉曼光谱显示糖玉表面少见红褐色矿物颗粒为金红石，由于金红石含量少，仅对颜色成因有部分贡献。

Color Genesis of Brown Jade from Hetian Nephrite

In order to study the color-genetic mechanism of brown jade, samples collected from Xinjiang were studied using XRD, ICP-MS, Raman and HRTEM. The results are as follows: the main mineral composition of brown jade is tremolite. ICP-MS data show that the concentration of the brown color has a good relationship with Fe element, samples with deeper color have higher Fe content. Fe occurs as iron mineral distributed in the tremolite particles or the microcracks. The grain size of the muddy iron mineral is extremely small, and the content is low. Experiments were designed to enrich the iron mineral with Stokes law. Then we studied the enriched samples with TEM and got the electron diffraction patterns of iron mineral, and identified them to be goethite. We conclude that the brown coloration of nephrite is due to goethite distributed in the tremolite particles or the microcracks. Raman spectra show that the rare mineral particle at the surface of the sample is rutile, and because of the low content, rutile has a little influence of the coloration.