巴基斯坦明格拉地区祖母绿的化学成分分析及其成因意义  

Chemical Composition Analysis of Emeralds from the Mingora Region,Pakistan:Insights into Formation Mechanisms

作　　者：赵红星 蔡景坤 许迎新 李雨璇 刘迎新[1] ZHAO Hongxing;CAI Jingkun;XU Yingxin;LI Yuxuan;LIU Yingxin(School of Gemmology,China University of Geosciences(Beijing),Beijing 100083,China;Beijing Guoshou Dikuang Gem Testing Co.,Ltd.,Beijing 100035,China)

机构地区：[1]中国地质大学(北京)珠宝学院,北京100083 [2]北京国首地矿珠宝鉴定有限公司,北京100035

出　　处：《现代地质》2025年第1期209-223,共15页Geoscience

基　　金：中国地质大学(北京)2024年度研究生创新资助项目(640224012)。

摘　　要：巴基斯坦斯瓦特地区的祖母绿因其独特的色泽和优异的晶体品质而备受关注,但该区明格拉祖母绿的化学成分尚未被系统研究。本研究采用电子探针显微分析(EMPA)和激光剥蚀电感耦合等离子质谱(LA-ICP-MS)技术,对明格拉矿床的祖母绿样品进行了系统的化学成分分析,旨在探讨其化学成分并揭示其形成过程中的地质环境影响。结果显示,明格拉祖母绿的类质同象替代程度平均为12.79%,主要发生在四面体T2位的铍(Be),归属于“四面体型”祖母绿。同时,其通道结构中碱金属离子的含量丰富,H_(2)O含量估算在2.28%至2.41%之间。值得注意的是,明格拉祖母绿在Cr-V含量图中显示,Cr含量均高于4500×10^(-6),明显高于其他国家产地的祖母绿。通过对铷(Rb)、铯(Cs)、钪(Sc)和锂(Li)等微量元素的对比分析,为祖母绿的产地鉴定提供了科学依据和新视角。The emeralds from the Swat region of Pakistan are notable for their unique color and exceptional crystal quality;however,the chemical composition of Mingora emeralds in this area has not been systematically studied.This research employs Electron Probe Microanalysis(EMPA)and Laser Ablation Inductively Coupled Plasma Mass Spectrometry(LA-ICP-MS)techniques to conduct a comprehensive chemical composition analysis of emerald samples from the Mingora deposit,aiming to explore their chemical properties and uncover the geological environmental influences during their formation.The results indicate that the average degree of isomorphous substitution in Mingora emeralds is 12.79%,primarily occurring at the tetrahedral T2 site of beryllium(Be),classifying them as“tetrahedral-type”emeralds.Additionally,the channel structure of these emeralds contains a rich concentration of alkali metal ions,with estimated H_(2)O content ranging from 2.28%to 2.41%.Notably,the projection of Mingora emeralds in the Cr-V content diagram shows that the chromium(Cr)content is consistently higher than 4,500×10^(-6),which is significantly higher than that of emeralds from other global sources.Through comparative analysis of trace elements such as rubidium(Rb),cesium(Cs),scandium(Sc),and lithium(Li),this study provides essential scientific supports and new insights for the provenance determination of emeralds.

关 键 词：巴基斯坦 明格拉 祖母绿 化学成分 微量元素 

分 类 号：P575.3[天文地球—矿物学]