中国三地软玉的矿物组成和成矿地质背景研究

Study on Mineral Components and Geological Background of Nephrites from Three Localities in China

为了查明新疆玛纳斯、青海格尔木、江苏溧阳产软玉的矿物组成和了解其品质与矿物组成的内在联系,为软玉的鉴别与质量评价等提供基础资料,采用偏光显微镜、电子探针、X射线粉末衍射等测试方法对3个产地的软玉样品进行了测试分析,从矿物成因特征、结构构造、矿物组成、化学成分等方面进行了对比分析。结果表明,新疆玛纳斯、青海格尔木、江苏溧阳的软玉虽然均由透闪石组成,但其晶体中Mg与Fe的离子数量明显不同,玛纳斯碧玉中的透闪石含有更多的Fe,其化学成分十分接近阳起石的;玛纳斯碧玉的成矿地质背景与格尔木和溧阳的有所差别,形成于蛇纹石化超镁铁岩中,富含FeOT和MgO,而溧阳和格尔木软玉则产于中酸性火成岩与白云质大理岩的接触带中,其FeOT的质量分数较低。软玉的颜色、韧性和透明度主要取决于其形成的地质背景条件。

In order to determine the mineral components of the nephrites from Manasi（Xin- jiang）, Geermu（Qinghai Province） and Liyang（Jiangsu Province）,and to understand the relation between the mineral components and properties of the nephrites and to provide the ba- sical data for the determination and valuation, the genesis, structures, mineral components and chemical compositions of the nephrite samples from the three localities are investigated by using the polarizing microscope, electron microprobe and X-ray powder diffraction. The results show that the nephrite samples from the three localities are consisted of tremolite with the varied amounts of Mg and Fe in the crystals. The chemical compositions of the tremolite in the nephrite sample from Manasi are very similar to that of the actinolite. The geological background of the samples from Manasi differs from that of the samples from Liy- ang and Geermu, the former is formed in ultramafite and contains more FeOT and MgO, while the latter is formed in the contact zone between neutral to acidic igneous rocks and dolomitic marble, with lower content of FeOT. The colour, tenacity and transparency of the nephrite samples are largely dependant on the conditions of geological background.