广西大化软玉的宝石矿物学特征

Gemmological and Mineralogical Characteristics of Nephrite from Guangxi

近期广西壮族自治区内发现了特色鲜明的新玉石矿,颜色多呈白色、灰白色,偶见青色,光泽多呈蜡状光泽,质优者可达油脂光泽,常见特征"松花"。通过折射率、密度等宝石学常规测试及红外吸收光谱、X射线粉末衍射、扫描电子显微镜等大型仪器测试,确定广西软玉的主要成分为透闪石矿物集合体,折射率、密度与新疆软玉接近。研究结果显示,广西软玉中透闪石微晶粒度均匀,交织紧密。根据透闪石的大小形态和结合方式,广西软玉可分为显微纤维交织结构、弱定向显微纤维结构、片状变晶结构等微观形貌特征,结构细腻,具有较高的工艺价值和开发利用前景。

Recently a new kind of jade with distinctive characteristics was found in Guangxi, the colour of which is mainly white, grey-white, and occasionally cyan. This jade is mostly of wax luster, and those high-quality ones could be of grease luster but the most distinctive feature is pattern of ＂Songhua＂. The samples collected from the mine are tested by conventional gemmological tests as refractive index, specific gravity, Fourier transform infrared （FTIR）, X-ray diffraction （XRD） and scanning electron microscope （SEM）. The results show that the mineral composition of the new jade is mainly tremolite, R.I. and S. G which is similar to nephrite from Xinjiang, and also show that tremolite grains are distributed even- ly and closely interwined. The textures of this jade can be classified into micro-fiber interwoven texture, weakly directional micro-fiber texture, and flaky metacryst texture. With dellcate structures, nephrite from Guangxi is of great prospects in market.