泰国玄武岩红宝石的宝石学及化学成分特征

Gemological and Chemical Composition Characteristics of Basalt-Hosted Rubies from Thailand

以产自泰国玄武岩的红宝石为研究对象,采用宝石学常规仪器、电子探针、LA-ICP-MS、紫外-可见光光度计、红外光谱、拉曼光谱等测试方法探究泰国红宝石的宝石学特征、化学元素特征、谱学特征,并与缅甸大理岩型红宝石、莫桑比克角闪岩型红宝石初步对比,分析产地特征。研究结果表明,泰国红宝石颜色较深,紫外光长波下多呈中等-弱红色荧光,短波下呈惰性;内部包裹体丰富,可见多种形态的固态、流体包裹体,双晶发育;化学成分主要为Al_(2)O_(3),含有Cr、Fe、Ti、Mg、V、Ga、Si、Ni等微量元素,以高Fe、高Mg、低Ga为特征。紫外-可见光吸收光谱为Cr+Fe谱,Cr相关荧光峰较弱,红外光谱测试样品为红宝石,拉曼光谱存在6个振动峰,与刚玉标准拉曼光谱重合度较高。通过对红宝石的外观、荧光性、内部所含固态包裹体、流体包裹体种类及形态可对红宝石初步进行产地鉴别;微量元素Cr、Fe、Mg、Ga、V、Ti含量具有明显产地特征;不同产地红宝石的紫外-可见光光谱在吸收峰值上略有差异。

We analyze the basalt-hosted ruby from Thailand to explore the gemological,chemical and spectral characteristics of ruby,by using gemological conventional instruments,EPMA,LA-ICP-MS,UV-Vis spectrophotometer,FTIR,Raman spectrometer and other testing methods.We then compare our data with the ruby from Myanmar and Mozambique,and identify the characteristics of different deposit origins.The results show that the Thai rubies have dark color,and they are mostly of medium-weak red fluorescence under UV-long wave and inert under UV-short wave.Internal inclusions are plentiful,with various forms of solid and fluid inclusions and twin-crystals.The rubies contain mainly Al_(2)O_(3),with trace elements including Cr,Fe,Ti,Mg,V,Ga,Si,and Ni,and are characterized by high Fe,high Mg and low Ga contents.The UV-Vis absorption spectral data show Cr and Fe,and the Cr-related fluorescence peak is weak.The infrared spectral test result shows ruby.There are six vibration peaks in Raman spectrum,which display high coincidence with the standard corundum Raman spectrum.The ruby origin can be identified by the ruby appearance,fluorescence,solid inclusions,and fluid inclusions.Contents of Cr,Fe,Mg,Ga,V,and Ti have obvious origin inheritance.The UV-Vis spectra of rubies from different origins have slightly different absorption peaks.