水热法合成的一种新型祖母绿宝石学及光谱学特征  

Gemological and Spectral Characteristics of a New Type of Emerald Synthesized by the Hydrothermal Method

作　　者：朱红伟 程佑法 李婷 马霄 丁秀云 范春丽 赵潇雪 陈淑祥[3] 胡建华 ZHU Hongwei;CHENG Youfa;LI Ting;MA Xiao;DING Xiuyun;FAN Chunli;ZHAO Xiaoxue;CHEN Shuxiang;HU Jianhua(Shandong Institute of Metrology,Jinan 250014,China;National Gold&Diamond Testing Center,Jinan 250014,China;Qilu University of Technology(Shandong Academy of Sciences),Jinan 250353,China;Shenzhen Shenzhi Testing Technology Co.,Shenzhen 518020,China)

机构地区：[1]山东省计量科学研究院,山东济南250014 [2]国家黄金钻石制品质量检验检测中心,山东济南250014 [3]齐鲁工业大学(山东省科学院),山东济南250353 [4]深圳市深智检测技术有限公司,广东深圳518020

出　　处：《岩矿测试》2023年第2期307-316,共10页Rock and Mineral Analysis

基　　金：山东省重点研发计划项目“山东长清木鱼石产业质量安全关键技术与标准研究”(2017GSF220015)。

摘　　要：水热法是合成祖母绿的常用方法之一,使用该方法合成的祖母绿具有典型“水波纹”状纹理,呈现锯齿状平行排列,且其红外透射吸收光谱在2300~3100cm^(-1)的特征峰是主要鉴定特征。但目前市场上新出现的水热法合成的一种祖母绿不具有上述典型特征。为探究这种水热法合成的祖母绿的宝石学和光谱学特征,本文采用常规宝石学仪器宝石显微镜、折射仪等及红外吸收光谱仪、紫外可见光谱仪、能量色散X射线荧光光谱仪(EDXRF)对其鉴定特征进行研究分析。结果表明:测试样品的折射率为1.571~1.588,双折射率为0.007~0.009,相对密度为2.56~2.78,多色性明显,这些特征与天然祖母绿相似,红外吸收光谱特征与天然祖母绿基本一致。在宝石显微镜下,从特定角度观察可见疑似水热法合成祖母绿的“水波纹”状纹理,呈平行状,但不是典型的锯齿状平行排列,属于疑惑样品。红外透射吸收光谱具有Ⅰ型水和Ⅱ型水的尖锐吸收峰,在2300~3100cm^(-1)范围内的吸收相对较弱,不具有诊断意义;紫外可见光谱分析表明Fe^(2+)离子引起的810~850nm吸收宽带不明显,但810~850nm范围内的特征吸收带是天然祖母绿的重要鉴定特征。能量色散X射线荧光光谱仪(EDXRF)分析显示样品含有异常高的Ni元素,其Ni元素的Κα峰强度远大于Cr元素的Κα峰强度(2倍以上),但研究表明世界各地的天然祖母绿中几乎不含Ni元素,或Ni元素含量低于Cr元素含量的2‰。经综合分析这种水热法合成的新型祖母绿的关键鉴定特征是,在结合紫外可见吸收光谱特征即Fe^(2+)离子引起的810~850nm吸收宽带不明显的同时,重点关注EDXRF测试结果,其Ni元素的Κα峰强度显著大于Cr元素的Κα峰强度。BACKGROUND:The emerald is loved by people because of its gorgeous color and is respected as one of the world’s four major gems.Due to the high value of emeralds,a variety of synthesis and optimization methods have emerged.The hydrothermal method is one of the common methods to produce synthetic emeralds.The emeralds synthesized by this method have typical water ripple texture,showing a serrated parallel arrangement,and the characteristic peaks of the infrared absorption spectrum in the range of 2300-3100cm^(-1) are the main identification feature.However,some emeralds synthesized by this method do not have the above typical characteristics.This has brought a great challenge to the quality inspection agencies,and brought many doubts to the majority of consumers,and affected the stability of the gem market.OBJECTIVES:It is essential to study the new emerald synthesized by this new hydrothermal method.The refractive index,density,polychromatism,and infrared absorption spectrum characteristics of the tested samples are very similar to those of natural emeralds,so infrared absorption spectrum analysis cannot obtain the supporting evidence of its cause.Based on this,the gemological and spectral characteristics of the test samples were studied by ultraviolet visible spectrum,energy dispersive X-ray fluorescence spectrometry(EDXRF)and other spectroscopic means.Finally,the test samples were determined to be a new kind of emerald synthesized by the hydrothermal method.METHODS:The refractive index,birefringence,relative density,polychromaticity and weight of the samples were tested by refractometer,electronic balance,and dichroic mirror.The internal and external characteristics of the test samples,the cutting and polishing quality of the samples,and the characteristics of internal inclusions were observed by gem microscope.The infrared reflection spectrum and infrared transmission spectrum characteristics of the samples were analyzed by Fourier transform infrared spectrometer and compared with the infrared spectrum charac

关 键 词：祖母绿 水热法 红外光谱法 紫外可见光谱法 X射线荧光光谱法 鉴定特征 

分 类 号：O657.33[理学—分析化学] O657.32[理学—化学]