一种独山玉相似品的矿物学特征

Mineralogical Characteristic of Dushan Yu Similar

由于与翡翠、祖母绿等颜色和表面特征的相似性,一种独山玉相似品正在我国市场中日渐兴起,利用电子探针、X射线粉末衍射仪、拉曼光谱仪等仪器对该独山玉相似品原石样品进行详细的矿物学研究,确定样品矿物组成为钙长石(An_(100))、钙铬榴石(Uvt_(49.66)Grs_(36.04 )Adr_(13.58)Prp_(0.67)Sps_(0.06))、透辉石、榍石、铬铁矿、黝帘石、葡萄石、杆沸石等,镜下观察样品为碎斑结构,根据变质岩命名规范,样品为钙铬榴石-钙长石碎斑岩。结合宝石学定名规范,宝玉石检测机构应定名为钙长石质玉。根据矿物组成及共生组合特征,结合前人资料分析,其成矿阶段包含岩浆阶段、变质阶段及后期热液改造阶段,钙铬榴石的形成依赖于铬铁矿提供的含Cr^(3+)热液。

With the similar colour and surface characteristics to the precious stones such as jadeite and emeralds,Dushan Yu similar sample has been a new market emerging stone in China.This papers made detail mineralogical characteristics of composition and structure on the rough samples by using electronic probe,X-ray powder diffraction,Raman spectroscopy and other instruments.The result showed that Dushan Yu similar sample is composed by anorthite(An_(100)),uvarovite(Uvt_(49.66)Grs_(36.04)Adr_(13.58)Prp_(0.67)Sps_(0.06)),diopsidite,sphene,chromite,zoisite,prehnite and thomsonite,et al.Through thin section observation,the sample showed mainly mortar texture.Based on the specification for nomenclature of metamorphic rocks,the sample were named as uvarovite-anorthite mortar rock.Combined with the specification for the gemological,the sample should be named as anorthitic jade.According to the composition paragenetic combination characteristics,combined with previous data,metallogenic stage of the samples contained magmatic stage,metamorphic stage and late hydrothermal transformation stage,and the formation of uvarovite depended on the Cr^(3+)hydrothermal originates from chromite.