越南安沛粉红色尖晶石的宝石学特征

Gemmological Characteristic of Pink Spinel from Yên Bái, Vietnam

  • 摘要: 越南北部的安沛省是粉红色尖晶石的新产地,目前缺乏关于该产地尖晶石的研究。以越南安沛粉红色尖晶石为研究对象,采用宝石学常规仪器,激光剥蚀等离子质谱仪和紫外-可见光吸收光度计, 荧光光谱仪等测试仪器进行系统性研究。结果表明,越南安沛粉红色尖晶石样品磨圆度较差,部分样品保留了原始晶形,为透明至半透明,荧光较强,表面有蚀痕等。显微镜下可见丰富的固体包裹体和液体包裹体,固体包裹体有八面体包裹体、管状包裹体等;液体包裹体大量分布在愈合裂隙中。紫外-可见吸收光谱基本一致,品红色样品由于其低V高Fe的特征,可与其他组样品区分开来。该批样品大部分显示强的粉红色荧光,强度略有差异,二维荧光光谱大致相同,显示Cr3+的特征谱线。成分测试显示该批尖晶石为镁铝尖晶石,主要化学成分为MgO和Al2O3,SiO2质量分数在0.70%~1.06%之间,CaO含量均低于0.1%,为典型的白云质大理岩型矿床尖晶石的化学特征。与其他产地大理岩型粉红色尖晶石成分特征进行对比分析,发现使用Fe/Sn、Ni、Zn等元素可将该产地尖晶石与塔吉克斯坦、坦桑尼亚的尖晶石区分,但是与缅甸尖晶石有部分重合。

     

    Abstract: Yên Bái in northern Vietnam is a new source of pink spinel, and there is a lack of research on spinel from this area.In this paper, the pink spinel samples from Yên Bái, Vietnam were systematically tested and studied by conventional gemmological instruments, laser denudation plasma mass spectrometer, ultraviolet-visible absorption spectrophotometer, fluorescence spectrometer and other testing instruments.The results showed that the spinel from Yên Bái have poor roundness, and some of the samples retained the original crystal shape, which are transparent to translucent, with strong fluorescence and etches on the surface.Rich solid inclusions and liquid inclusions can be seen under the microscope, such as octahedral inclusions, tubular inclusions, and a large number of liquid inclusions are distributed in healing fissures.The UV-Vis absorption spectra of the samples were basically the same and the magenta samples can be distinguished from other groups of samples due to its low V and high Fe characteristics.Most of the samples showed strong pink fluorescence with slightly different intensities, and the two-dimensional fluorescence spectra were approximately the same, showing characteristic lines of Cr3+. The results also showed that the main chemical compositions of the tested samples are MgO and Al2O3, the mass fraction of SiO2 is between 0.70% - 1.06%, and the content of CaO is less than 0.1%, which is a typical chemical characteristic of dolomitic-marble type deposit spinel.Compared with marble type pink spinels from other areas, it is found that the marble type pink spinel from this area can be distinguished from the spinels from Tajikistan and Tanzania by using Fe/Sn, Ni, Zn and other elements, but there is a partial overlap with the spinel from Myanmar.

     

/

返回文章
返回