坦桑石的矿物学及谱学特征研究  

Mineralogical and Spectral Characteristics of Tanzanite

作　　者：赖萌 廖宗廷[1,2,3] 杨如增[1,2,3] 周征宇 钟倩 LAI Meng;LIAO Zong-ting;YANG Ru-zeng;ZHOU Zheng-yu;ZHONG Qian(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092 ,China;Shanghai Engineering&Technology Research Center for Gem and Materials Technics,Shanghai 200092,China;Ocean and Earth Science School,Tongji University,Lab of Gem and Technological Materials,Shanghai 200092,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]上海宝石及材料工艺工程技术研究中心,上海200092 [3]同济大学海洋与地球科学学院,宝石及工艺材料实验室,上海200092

出　　处：《光谱学与光谱分析》2018年第9期2872-2876,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(41272049),上海市科委专项基金项目(15DZ2283200,12DZ2251100)资助

摘　　要：对来自坦桑尼亚Merelani地区的坦桑石样品,分别采用电子探针、EMXPLUS型ESR谱仪、同步热分析仪、紫外可见光谱仪以及傅里叶变换红外光谱仪进行了测试与分析。结果表明:坦桑石样品的主要成分为SiO_2,Al_2O_3和CaO,微量成分中V_2O_5含量相对最多,平均含量为0.36%;坦桑石样品本身不含吸附水,结晶水,加热至780℃附近时,脱失结构水,样品中结构水大约占总质量的2%;ESR实验结果中显示出明显Fe^(3+)和Mn^(2+)的电子顺磁信号;紫外-可见光谱显示,样品在385nm处出现吸收窄带,575和750nm处分别出现较为宽缓的吸收;红外光谱测试表明,样品在6 500~9 000cm^(-1)波段的倍频振动区,基本没有吸收。在4 000~6 500cm^(-1)波段主要为和频振动,5 956cm^(-1)附近呈较宽缓的吸收峰,5 413,5 184,4 336和4 046cm^(-1)处出现较尖锐的吸收峰,主要可能由O—H,矿物内的Si—O,以及空气里面的H_2O分子和CO_2振动所引起。综合EPMA以及ESR分析结果,蓝-紫色坦桑石颜色可能主要由V^(3+)和V^(5+)共同引起,Fe^(3+)晶体场的d—d电子跃迁、Fe^(2+)→Ti^(4+)的电荷转移辅助致色。In this paper,the Tanzanite samples from Merelani Tanzania have been respectively tested and analyzed by electron probe,EMXPLUS ESR spectrometer;SDT,UV VIS spectrometer and Fu Liye transform infrared spectrometer.The results show that:the Tanzanite samples are mainly composed of SiO 2,Al 2O 3 and CaO,V 2O 5 has the content of 0.36%,which is the most trace components;TG-DTA curves show that there is no absorption water and crystal water in Tanzanite samples,when being heated to 780℃,the structural wateris lost,the water in the samples is about 2%of the total mass;ESR results shows obvious Fe^3+and Mn^2+electron paramagnetic signal;UV Vis spectra shows that an narrow-band absorption appears at 385 nm while a wide-bandabsorption appears respectively at 575 and 750 nm;infrared spectra shows that there is no absorption in 6 500~9 000 cm^-1 of the Tanzanite samples.The 5956 cm^-1 is a wide absorption peak,and there is a sharp absorption peakrespectively at 5 413,5 184,4 336,and 4 046 cm^-1,which are mainly caused by the O-H,the Si-O within in the minerals as well as H 2O and CO 2 inside the air environment.Based on the results of EPMA and ESR analysis,the color of blue-violet Tanzanite may be mainly caused by V^3+and V 5+,d-d electron transition of the crystal field of Fe^3+and charge transferof Fe^2+to Ti^4+to assist coloration.

关 键 词：坦桑石 谱学特征 颜色成因 矿物学特征 

分 类 号：O657.3[理学—分析化学]