祖母绿宝石微量元素指纹的PIXE和PIGE研究

TRACE ELEMENT FINGER PRINTING OF EMERALD BY PIXE AND PIGE

摘要: <正> 一、引言祖母绿宝石是普通矿物绿柱石或绿玉的一种。它的化学分子结构可以表示为:Be_3Al_2(SiO_3)_6=(BeO)_3+(Al_2O_3)+(SiO_2)_6。从分子结构计算三个主体组份的含量BeO约占14％,Al_2O_3约占19％,SiO_2约占67％。在祖母绿宝石结晶生长的过程中,这些主体元素组份可以部份地被一些微量元素所替代。替代元素的含量和元素间浓度的分布状况既给出祖母绿宝石的特征,又是形成此矿物所处地质化学和地质物理环境的指证。祖母绿宝石突出的特征是替代元素Cr使它呈现美丽的绿色。当受到质子束轰击时,样品的靶点上被激发出浓艳的红色荧光。祖母绿宝石微量元素组份的测定可提供此矿物来源地的地质环境的有价值资料。这些资料有可能指明宝石的产地,从而对于确定宝石本征价值以及人造宝石是否

Abstract: The concentrations of 18 major- and minor-elements in 12 Emeralds from different mines and two synthetic ones are measured with proton induced X-ray emission (PIXE) and y-ray emission (PIGE) . The concentration and distribution of 18 elements are used to establish the characteristic finger print pattern of each Emerald. With the help of cluster analysis of SYSTAT statistical package for IBMPC, these finger prints are analysed, from which a quantitative description of the dissimilarities between Emeralds can be given.