马达加斯加Ilakaka蓝宝石的包裹体和谱学特征

Inclusion and Spectral Characteristics of Sapphire from Ilakaka, Madagascar

采用激光拉曼光谱仪、傅里叶变换红外光谱仪、激光剥蚀等离子体质谱仪、紫外-可见-近红外吸收光谱仪及荧光光谱仪等测试技术,对马达加斯加Ilakaka蓝色和浅橙色蓝宝石的包裹体及相关谱学特征进行研究,旨在丰富马达加斯加Ilakaka矿区蓝宝石的产地特征信息。结果表明,该产地蓝宝石的特征包裹体包括大量由液态CO_(2)充填的负晶、与愈合裂隙相关的假次生包裹体以及方解石、石墨、金云母、金红石和赤铁矿等固体包裹体;蓝宝石中Fe元素的含量与其蓝色调深浅呈正相关性,均见与Fe^(3+)相关的377、387 nm和451 nm处吸收线,并且Fe含量的增高可促成Fe^(3+)-Fe^(3+)交换耦合离子对形成,从而增强377 nm和451 nm处的吸收;蓝宝石的荧光光谱基本均可见Cr^(3+)的R_(1)(694 nm)、R_(2)(693 nm)荧光线;浅橙色蓝宝石在400~480 nm处出现明显荧光宽峰,通过低温退火实验发现该组荧光峰热稳定性差,加热至250℃时趋于消失,而在300℃时荧光峰明显增强,推测与空穴心[V_(Al)+O^(-)]与[Mg^(2+)+O^(-)]相关。

The inclusions and spectral characteristics of blue and orange sapphire from Ilakaka,Madagascar have been studied by Raman spectroscopy,infrared spectroscopy,LA-ICP-MS,UV-Vis-NIR absorption spectroscopy and fluorescence spectroscopy.This study aimed to enrich the information of characteristics of sapphire from Ilakaka,Madagascar.The results showed that the characteristic inclusions of sapphire from Ilakaka included a large number of liquid CO_(2)-filled negative crystals and healed fissures filled with pseudosecondary inclusions such as goethite and sulfur.It also contained a variety of solid inclusions,such as calcite,graphite,phlogopite,rutile,hematite and kaolinite.The content of Fe in sapphire was positively correlated with the intensity of blue tone.The absorption lines at 377,387 nm and 451 nm associated with Fe^(3+) were found in all types of sapphire,and the increase of Fe content could promote the formation of Fe^(3+)-Fe^(3+) exchange-coupled ion pairs and enhance the absorption at 377 nm and 451 nm.R_(1)(694 nm)and R_(2)(693 nm)fluorescence lines of Cr^(3+)were observed in the fluorescence spectra of almost all samples.Orange sapphires had wide fluorescence peaks at 400-480 nm.The low temperature annealing experiment showed that these fluorescence peaks had poor thermal stability and tended to disappear when heated to 250℃,while the fluorescence peaks increased significantly when heated to 300℃.The thermo behavior of those florescence peaks may be associated with hole centers[V_(Al)+O^(-)]and[Mg^(2+)+O^(-)].