宝石级斜硅镁石的谱学表征  

Spectral Characteristic of Gem Grade Clinohumite

作　　者：吴燕菡 刘衔宇 徐娅芬 涂彩 李净净 WU Yanhan;LIU Xianyu;XU Yafen;TU Cai;LI Jingjing(School of Jewellery,Shanghai Jian Qiao University,Shanghai 201306,China)

机构地区：[1]上海建桥学院珠宝学院,上海201306

出　　处：《宝石和宝石学杂志(中英文)》2025年第1期39-47,共9页Journal of Gems & Gemmology

基　　金：上海市高校优秀青年教师培养基金(晨光计划)(项目号:AASH2106);上海建桥学院博士项目基金资助。

摘　　要：斜硅镁石是一种稀有的黄色至橙色的硅酸盐矿物,近年来市面上开始出现宝石级的斜硅镁石,而国内鲜有相关的宝石学研究。为补充该宝石的研究空白,选取三种不同色调(黄色、橙黄色和橙红色)的斜硅镁石进行常规宝石学测试,结合电子探针、激光拉曼光谱、傅里叶变换红外光谱和紫外-可见光谱分析技术,对斜硅镁石的化学成分、光谱特征及颜色成因等进行初步研究。结果表明,斜硅镁石的折射率为1.629~1.668,具有较强的双折射(DR:0.031~0.036),相对密度为3.14~3.27,短波紫外光下呈中等黄色-橙色荧光;部分样品有明显聚片双晶,包裹体形态丰富,并发现金红石包裹体;斜硅镁石含有主量元素Si、Mg和Ti,微量元素Ca、Fe、K和V,结合紫外-可见光谱推测颜色与Fe和Ti密切相关;拉曼光谱和红外光谱都显示主要峰位与SiO 4四面体、MgO_(6)八面体和-OH的振动有关,最强拉曼位移为830 cm^(-1)和862 cm^(-1),最强红外光谱反射峰在925~935 cm^(-1)附近,都与SiO_(4)振动有关。Clinohumite is a rare yellow to orange silicate mineral.In recent years,gem grade clinohumite has appeared on the market,but there are few related gemmological studies in China.To supplement the research gap of this gemstone,clinohumite samples of three different colour tones(yellow,orange-yellow and orange-red)were selected for conventional gemmological tests.Combined with electronic probe,laser Raman spectrometer,Fourier transform infrared spectrometer,and UV-Vis spectrometer,the chemical compositions,spectral characteristics,and mechanism of coloration were preliminarily studied.The results show that RI of clinohumite is 1.629-1.668,with a strong birefringence(DR:0.031-0.036).Their relative density ranges from 3.14 to 3.27,and medium yellow to orange fluorescence can be observed under shortwave ultraviolet light.Some samples have obvious twin crystal patterns and rich inclusion morphology.Rutile inclusions were found in gemstone grade clinohumite.Clinohumite contains main elements Si,Mg,and Ti,as well as trace elements Ca,Fe,K,and V.Combined with UV-Vis spectra,it is speculated that the colour is closely related to Fe and Ti.Laser Raman spectra and infrared spectra are mainly related to vibrations of SiO_(4) tetrahedron,MgO_(6) octahedron and-OH.The strongest Raman shifts(830 cm^(-1) and 862 cm^(-1))and the strongest infrared spectral reflection peaks(around 925-935 cm^(-1))both related to SiO_(4) vibration.

关 键 词：斜硅镁石 拉曼光谱 红外光谱 紫外-可见光谱 

分 类 号：TS93[轻工技术与工程]