内蒙古角力格太碧玺的宝石学和产地特征  

Gemmological and Locality Characteristics of Tourmaline from Jiaoligetai,Inner Mongolia

作　　者：盛湘旗 杨云淇 王浩天 黄慧敏 王朝文 SHENG Xiangqi;YANG Yunqi;WANG Haotian;HUANG Huimin;WANG Chaowen(Gemmological Institute,China University of Geosciences,Wuhan 430074,China;Hubei Gems and Jewelry Engineering Technology Research Center,Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)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

出　　处：《宝石和宝石学杂志(中英文)》2024年第6期1-14,共14页Journal of Gems & Gemmology

基　　金：国家自然科学基金项目(42072056);中国地质大学(武汉)教学实验室开放基金项目(SKJ2022218)。

摘　　要：内蒙古乌拉特中旗角力格太地区产有大型的伟晶岩宝石矿床,产出丰富的碧玺。本文借助常规宝石学测试、电子探针测试、激光剥蚀电感耦合等离子体质谱、红外光谱、紫外-可见光吸收光谱和拉曼光谱对角力格太碧玺的宝石学特征和矿物学特征进行系统的研究。通过与其他产地(巴西、赞比亚、阿富汗、新疆)碧玺进行对比,总结了角力格太碧玺的产地特征。结果表明,角力格太碧玺样品主要有蓝色和绿色两个品种,在紫外荧光下样品荧光均呈惰性,折射率为1.615~1.650,双折率为0.015~0.020;相对密度为3.050~3.158,颜色深者密度大。角力格太碧玺内部含有丰富的无定形碳、微小碧玺晶体、CO_(2)气液两相包裹体等内含物,裂隙中存在碳质充填。根据化学成分特征,蓝色、绿色角力格太碧玺属于锂电气石,黑色角力格太碧玺属于黑电气石。红外光谱和拉曼光谱均表现出电气石典型的硅氧和硼氧基团吸收。紫外-可见光吸收光谱显示414 nm和720 nm处的吸收带,为其呈蓝绿色的原因。相较于其他产地,角力格太碧玺的Fe、Mn含量较高,w_(FeO)/wAl_(2)O_(3)和w_(MnO)/w_(FeO)存在一定的线性相关关系,微量元素中Zn、Sr、Pb含量较高。A large pegmatite gem deposit containing tourmaline with significant development potential was found in the Jiaoligetai of Inner Mongolia.In this paper,the gemmological and mineralogical characteristics of the tourmaline were systematically studied by conventional gemmological tests,electron probe tests,laser ablation inductively coupled plasma mass spectroscopy,infrared spectra,ultraviolet-visible absorption spectra and Raman spectra.The characteristics of the tourmaline were summarized and compared with those of the other sources.The results showed that tourmaline samples from Jiaoligetai can be classified into two main varieties:blue and green.The fluorescence characteristics of the samples were inert under UV fluorescence,the refractive index ranges from 1.615 to 1.650,and the birefringence ranges from 0.015 to 0.020.The relative density is 3.050—3.158,and the value of dark one is higher.There are abundant inclusions of amorphous carbon,tiny tourmaline crystal,CO_(2)-bearing gas-liquid two-phase inclusions,and carbon filling in cracks.Based on chemical composition tests,the blue and green tourmaline samples from Jiaoligetai are elbaite,while the black ones are schorl.Both IR and Raman spectra show typical absorption of silicate and borate groups in tourmaline.UV-Visible absorption spectra show absorption bands at 414 nm and 720 nm,which cause the green and blue colour.Compared to other origins,the distinctive characteristics of Jiaoligetai tourmaline are higher Fe and Mn content,a certain linear correlation between w_(FeO)/wAl_(2)O_(3) and w_(MnO)/w_(FeO),and the trace elements Zn,Sr,and Pb have higher concentrations.

关 键 词：电气石 电子探针 激光剥蚀电感耦合等离子体质谱 拉曼光谱 产地特征 

分 类 号：TS93[轻工技术与工程]