一种“银线石”的宝石矿物学研究

＂银线石＂是在广州市场上销售的一种低档宝石材料,已有检测机构将其定名为顽火辉石。为了确定其定名,为珠宝鉴定工作提供有用信息,采用常规的宝石学方法,EPMA,IR,XRD及SEM等大型仪器对＂银线石＂样品进行了研究与分析。结果表明,＂银线石＂为黑色-灰黑色,具交替闪现的金属状反光条带的特征外观,折射率为1.69（点测）,摩氏硬度为5～6,密度为3.45g/cm3;主要矿物组成为斜方辉石亚种的紫苏辉石;紫苏辉石矿物的微细纤维状结构及相邻纤维带存在角度的排列方式,可能是＂银线石＂呈现特征外观的原因。＂银线石＂的外观特征和较高的密度值均属其鉴定特征,可与顽火辉石区分。

Study on Gemmological and Mineralogical Characteristics of ＂Silver Line Stone＂

A kind of cheap gem material——＂Silver Line Stone＂,which is recently sold in Guangzhou market,has been identified as enstatite by some testing institutions.In order to name this kind of stone and to provide useful information for the identification work,this paper investigates the ＂Silver Line Stone＂ samples by using the conventional gemmological methods and large-scale instruments（EPMA,IR,XRD and SEM）.The results show that the ＂Silver Line Stone＂ is characterized by this appearance： black,grey black and metallic luster reflecting light band.Its refractive index is 1.69,its Mohs＇hardness is 5~6,and its density is 3.45 g/cm3.It is mainly composed of hypersthene——a subspecies of orthorhombic pyroxene.The appearance of the ＂Silver Line Stone＂ may be caused by the micro-fine fiber structure of hypersthene and the angular arrangement of the contiguous fibrous bands.＂Silver Line Stone＂ could be easily distinguished from enstatite by its appearance characteristics and higher density.