一种绿松石仿制品的宝石学特征研究

STUDY ON GEMOLOGICAL CHARACTERISTICS OF A KIND OF TURQUOISE IMITATION

近期在市场上出现一种绿松石仿制品,外观与天然绿松石极为相似,极具迷惑性。采用常规宝石学测试方法、红外吸收光谱、显微红外吸收光谱、紫外可见吸收光谱、X荧光能谱对其宝石学性质、光谱特征进行了系统研究分析。结果表明:这种绿松石仿制品具有粒状结构,可见角砾状颗粒,颜色分布均匀,具有典型的再造宝石特征。该绿松石仿制品折射率为1.56,与绿松石一致,相对密度为2.34,略低于绿松石。无损显微红外吸收光谱显示该绿松石仿制品主要由顽火辉石与石英组成,并含有胶结物质。顽火辉石的红外吸收峰为1083 cm^(-1),1009 cm^(-1),938 cm^(-1),855 cm^(-1),721 cm^(-1),647 cm^(-1),505 cm^(-1),478 cm^(-1),424 cm^(-1)。石英的红外光谱吸收峰为1182 cm^(-1),1112 cm^(-1),800 cm^(-1),692 cm^(-1)。有机胶结物的红外吸收峰为2978 cm^(-1),2937 cm^(-1),2878 cm^(-1),3055 cm^(-1),3035 cm^(-1),1612 cm^(-1),1512 cm^(-1),1385 cm^(-1),1458 cm^(-1)。X荧光光谱分析显示主要含有Ba,Ti,Sr,Fe,Ni,Zn元素,与绿松石的成分不相符。紫外可见光谱分析显示在680 nm、630 nm处具有吸收带,应是样品呈现蓝绿色的原因。本次研究旨在利用无损检验方法确定样品为仿绿松石,并确定有环氧树脂胶结物的存在。

Currently,a kind of turquoise imitation appears on the market,which is deceptive,with similar appearance to natural turquoise.The gemological properties and spectral characteristics of turquoise imitation are systematically studied and analyzed by conventional gemological testing methods,infrared absorption spectrum,microscopic infrared absorption spectrum,Ultraviolet-visible absorption spectrum and X-ray fluorescence energy spectrum,in order to identify turquoise and imitation turquoise by nondestructive testing and determine the presence of epoxy resin cement.The results show that the turquoise imitation has granular structure,visible brecciate particles and uniform color distribution,which is typical of the reproduced gem.The refractive index of the turquoise imitation is 1.56,being consistent with that of natural turquoise,and the relative density is 2.34,slightly lower than that of natural turquoise.The analysis of non-destructive microscopic infrared absorption spectra shows that the turquoise imitation is mainly composed of enstatite and quartz,and contains cementing material.The infrared absorption peaks of enstatite are 1083 cm^(-1),1009 cm^(-1),938 cm^(-1),855 cm^(-1),721 cm^(-1),647 cm^(-1),505 cm^(-1),478 cm^(-1),424 cm^(-1).The infrared absorption peaks of quartz are 1182 cm^(-1),1112 cm^(-1)、800 cm^(-1) and 692 cm^(-1).The infrared absorption peaks of organic cements in turquoise imitation are 2978 cm^(-1),2937 cm^(-1),2878 cm^(-1),3055 cm^(-1),3035 cm^(-1),1612 cm^(-1),1512 cm^(-1),1385 cm^(-1) and 1458 cm^(-1).X-ray fluorescence spectrum analysis shows that turquoise imitation contains Ba,Ti,Sr,Fe,Ni,Zn,which is not consistent with the compositions of natural turquoise.Ultraviolet-visible spectrum analysis shows that there are absorption bands at 680 nm and 630 nm,which should be the reason for the blue-green color of the sample.This paper aims to use nondestructive testing methods to determine the imitation turquoise samples and determine the presence of epoxy resin cement.