溧阳软玉的岩石矿物学研究

A petrological and mineralogical study of Liyang nephrite

对采自江苏溧阳小梅岭软玉矿区的软玉样品进行了化学成分、扫描电镜、X射线粉晶衍射物相定性和结晶度等分析,确定其主要为透闪石矿物集合体,并具有显微纤维、柱状及片状3种特征结构。将分析结果与新疆软玉进行对比,发现溧阳软玉普遍显示出透闪石含量稍低、透闪石纤维(片晶)定向性良好以及结晶度偏高的特点,这与溧阳软玉矿区动力改造相对较弱密切相关;溧阳软玉显示出ALK含量(>0.51)高于新疆等其他产地(普遍<0.46)的特点,这与其成矿母岩含碱量偏高关系密切。成矿地质条件的不同是造成溧阳与新疆两地所产软玉在上述岩石矿物学特征上巨大差异的根本原因,也是造成溧阳软玉透明度高、油润度不足、工艺加工性能不高的主要原因。

ICP test, SEM observation and quantitative and crystallinity analysis of mineral phases of Liyang nephrite have revealed that tremolite fiber has higher crystallinity and better orientation than Xinjiang nephrite, which might be attributed to its weaker dynamic reconstruction. Compared with geological characteristics of other nephrite deposits in China, the parent rock of the Liyang nephrite deposit has extremely abundant ALK, which is believed to be the main cause for the higher contents of ALK in Liyang nephrite. This feature is also regarded as one of the identification characteristics. Specific geological features of the Liyang deposit are responsible for petrological and mineralogical characteristics of Liyang nephrite and also account for the higher transDarenev and lower oil luster of Liyang nephrite.