钙铝榴石玉仿翡翠的宝石学特征

Gemmological Characteristics of Grossular Jade as Jadeite Imitation

近期,广东省肇庆市四会市天光墟玉石市场上出现一种绿色仿翡翠的玉石,常作为圆形手串或项链出售。采用常规的宝石学仪器对该样品的折射率、密度、发光性等进行了测试。为确定其矿物组成、结构特征和微量元素,采用傅里叶变换红外光谱仪、X射线粉末衍射仪、紫外-可见吸收光谱仪及X射线荧光能谱仪等对其进行了研究。结果显示,该样品的折射率为1.70,密度为3.32g/cm3,粒状结构,其主要矿物组成为钙铝榴石、透辉石、符山石和钠长石,另含有少量镍绿泥石及钠钾云母;样品中的钙、铁含量高,另含微量的铬、钒、镍、铜;其主要致色元素为铬、铁。

In recent jewelry market of Sihui,Guangdong Province,a new jadeite imitation appears and is sold as cabochon bracelet or necklace.According to the results of conventional tests,the refractive index of sample is about 1.70 and density is about 3.32g/cm3.To make sure the mineral components,structure characteristics and trace elements,infrared spectrometer,X-ray powder diffraction spectrometer,ultraviolet-visible spectrophotometer,Xray fluorescence spectrometer were used for further research.The X-ray diffraction patterns show that the main mineral components of samples are grossular,diopside,vesuvianite and albite.The result of X-ray fluorescence demonstrates that the main chemical compositions of the sample are Ca and Fe and it also contains a small quantity of Cr,V,Ni and Cu.The colour causing elements of samples are mainly Cr and Fe.