不同产地软玉品种的矿物组成、显微结构及表观特征的对比研究

Comparative Study on Mineral Components,Microstructures and Appearance Characteristics of Nephrite from Different Origins

采用偏光显微镜、X射线粉末衍射仪、扫描电子显微镜、ICP-MS等分析测试方法,对目前市场上主要的软玉品种的化学成分、矿物组成、显微结构及表观特征进行了综合对比研究,结果表明,不同产地软玉品种的主要化学成分和主要矿物相似,微量元素及次要矿物存在差异,对产地和品种鉴别具有一定的指示意义。一般而言,新疆白玉及青白玉、优质的青海白玉、俄罗斯白玉具有毛毡状隐晶质变晶结构,透闪石质量分数高,纤维细小且紧密交织,反映在外观上质地细腻油润、光泽柔和,韧性强。新疆青玉、部分青海白玉、烟青玉、岫岩软玉以及韩国白玉以显微纤维交织结构、显微纤维-叶片状交织结构、显微纤维-粒状变晶结构及斑状变晶结构为主,透闪石质量分数相对较低,纤维粗且纤维之间的空隙大,表现在外观上质地粗糙,油润感差,韧性降低。新疆、俄罗斯及加拿大碧玉的结构类型和结晶度相似,表观特征差别不大。

Nephrite is mainly sold on the market in China （Xinjiang, Qinghai Province and Liaoning Province）, Russia, Canada, South Korea and other places at present. The main kinds of jade are white jade, grayish jade, gray jade and green jade. Jade from different ori- gins show the similar characteristics in mineralogy and petrology. However, it shows subtle differences in nephrite appearance from different origins due to the differences in mineral as- semblages and tremolite crystallinity, particle size and arrangement. This study is aiming to find the common and different characteristics of nephrite from various orgins and to provide a more detailed theoretical guidance for identification. Using polarizing microscope, X-ray powder diffraction, scanning electron microscopy （SEM） and ICP-MS, the chemical compositions, mineral assemblage, microstructures and appearance characteristics of the main varieties of nephrite are studied. The results show that the chemi- cal compositions and main minerals of nephrite from different origins are similar. However,there are differences in trace elements and secondary minerals, which could be a certain sig- nificance for identification. In general, white jade and grayish jade from Xinjiang, high quali- ty white jade from Qinghai Province and Russia are flet-like cryptocrystalline blastic texture with high content of tremolite, where fiber structure is small and closely intertwined. There- fore, the jade is fine, glossy in appearance. While gray jade from Xinjiang, part of white jade, grayish jade from Qinghai Province, white jade from Xiuyan and South Korea are mi- cro-fihrous interlocking texture, microfibre flaky blastic texture, microfibre granular crystal- loblastic texture and porphyroblastic texture. Content of tremolite in jade from those areas is relatively low, and fibers are coarse with large gap, which lead to rough texture and poor gloss in appearance and toughness decreasing. The structural types and crystallinity of jasper from Xinjiang, Russia and Canada are similar and it shows little difference in appearance characteristics.