一种新型绿松石仿制品的谱学特征研究

The Gemmological Characteristics of a New Kind of Imitation of Turquoise

近年来,一种绿松石的伴生石矿物作为绿松石仿制品在市场上出现,被称为"紫罗兰"、"白水牛"等,日益受到消费者的欢迎。通过常规宝石学基本测试及X射线荧光光谱仪、傅里叶变换红外光谱仪、X射线粉晶衍射仪、扫描电镜、紫外-可见光分光光度计等测试技术,对市场上这种称做绿松石伴生石的玉石进行了化学成分、矿物组成、微观结构和光谱特征的综合测试分析,并对其呈色机制进行了探讨。X射线荧光光谱显示样品的化学成分较复杂,不同颜色的样品所含元素基本一致,主要有Ca,Al,P,Cu,Si,K,Fe和Ba等元素;根据样品红外光谱的峰位及强度可以推断样品所含的阴离子团主要是PO_4^(3-);由样品的X射线粉晶衍射可推断该玉石主要矿物为纤磷钙铝石、磷钙铝石;扫描电镜显示样品致密,由无数鳞片状、叶片状及不规则粒状集合体组成;通过对可见光吸收光谱的分析,推测样品是由Fe^(3+)离子中的电子跃迁致色,Fe^(3+)含量不同导致样品颜色不同。

A new kind of imitation of turquoise named “Violet”and “White buffalo”which is a type of associated mineral of tur-quoise have appeared on the market recently and are becoming increasingly popular.Conventional instruments,X-ray fluores-cence spectrometer,Infrared spectrometer,X-ray powder diffraction,Scanning electronic microscope,UV-Vis have been em-ployed to discuss the gemmological characteristics of this kind of imitation of turquoise in this paper,to study their chemical composition,mineral composition,microstructure,spectral characteristics and color emerging mechanism.The X-ray fluores-cence spectrum shows that the chemical composition of the sample is complicated.The basic elements of different-colour samples are basically identical which contains of Ca,Al,P,Cu,Si,K,Fe,Ba.It can be deduced from the intensity of infrared absorp-tion bend that the major anion group of this kind of imitation of tuequoise is PO3-4 .The analysis for X-ray powder diffraction da-ta indicated that the major mineral of the sample is crandallite and woodhouseite.Meanwhile,the scanning electron microscopy showed that the structure of the dense sample is determined by numerous of scaly,leaf-shaped and irregular granular aggregates. With the study of absorption spectrum,the conclusion is drawn that Fe3＋ electronic transitions are the main factor for coloring of the sample and color varies with the content of Fe3＋.