巴西Bahia矿区祖母绿成分及谱学特征研究  

Study on the Chemical Composition and Spectroscopy Characteristics of Emeralds from Bahia Mining Area,Brazil

作　　者：华剑阳 狄敬如[1,3] HUA Jianyang;DI Jingru(Gemmological Institute,China University of Geosciences,Wuhan 430074,China;Hubei Gems and Jewelry Engineering Technology Research Center,Wuhan 430074,China;Hubei Songshi Testing Technology Co.,Ltd.,Shiyan 442000,China)

机构地区：[1]中国地质大学珠宝学院,湖北武汉430074 [2]湖北省珠宝工程技术研究中心,湖北武汉430074 [3]湖北省松石检测技术有限公司,湖北十堰442000

出　　处：《宝石和宝石学杂志（中英文）》2022年第5期109-117,共9页Journal of Gems & Gemmology

基　　金：绿松石工艺和机理研究项目(KH2260304);中国地质大学(武汉)珠宝检测技术创新中心项目(CIGTWZ-2021002)资助。

摘　　要：本文对巴西Bahia矿区祖母绿的基本宝石学特征、成分特征、红外光谱特征、紫外-可见光谱特征进行研究,旨在探讨巴西Bahia矿区祖母绿成分特征和谱学特征,为祖母绿的产地溯源及巴西祖母绿的鉴定提供帮助,并对国内巴西祖母绿研究进行补充。研究结果表明,巴西Bahia矿区祖母绿是典型的富Cr型祖母绿,其Cr/V比值大于6.9,Fe含量较高。样品中碱金属元素主要为Li、Na、K、Cs,总含量较高,平均值为12052 ppm。Bahia祖母绿的红外光谱测试结果表明其Ⅱ型水相关吸收较强,5270 cm^(-1)左右的吸收峰较特征,指示较高的碱金属含量。Bahia祖母绿的紫外-可见光谱的特征吸收分别为:426 nm、607 nm左右Cr^(3+)和V^(3+)联合作用产生的吸收带、637 nm、683 nm处Cr^(3+)相关吸收以及835 nm左右Fe^(2+)相关吸收带。结合成分测试结果发现:Cr含量较低时,紫外-可见光谱中607 nm左右吸收带的中心偏移,637 nm尖锐吸收峰缺失,662 nm和682 nm左右的吸收峰强度增加。In this paper,the basic gemmological,compositional,infrared spectral and UV visible spectral characteristics of emeralds from Bahia mine,Brazil,are studied,aiming to explore the chemical composition and spectrum characteristics identification of emeralds from Bahia mine,to provide assistance for the origin identification of emeralds and the identification of emerald from Brazil,and to supplement domestic research of emerald from Brazil.The results show that emeralds from Bahia are typical Cr^(-) rich emeralds with a Cr/V ratio greater than 6.9 and a high Fe content.The alkali metal elements in the samples are mainly Li,Na,K and Cs,and the total content is high,with an average value of 12052 ppm.The infrared spectroscopic test results of emeralds from Bahia show that their typeⅡwater-related absorption peaks are strong,and the absorption peak of about 5270 cm^(-1) is more characteristic,indicating a higher alkali metal content.The characteristic absorptions of the UV-Vis spectrum of emeralds from Bahia are as follows:the absorption band produced by the combined action of Cr^(3+) and V^(3+) are at about 426 nm and 607 nm,the Cr^(3+) related absorption peaks are at 637 nm and 683 nm,and the Fe^(2+) related absorption band is at about 835 nm.The results of the combined composition test show that when the Cr content is low,the center of the absorption band of about 607 nm is shifted in the UV-visible spectrum,the sharp absorption peak of 637 nm is missing,and the intensity of the absorption peaks at about 662 nm and 682 nm increaseds.

关 键 词：祖母绿 成分分析 红外光谱 紫外-可见光谱 巴西Bahia 

分 类 号：TS93[轻工技术与工程]