光石沟晶质铀矿:一种潜在的铀矿物电子探针定量分析标准样品

电子探针定量分析是采用元素A在待测样品中的特征X射线强度与标准样品中元素A特征X射线强度相比较而进行的,要实现未知样品的元素定量分析必须要具有相应的标准样品,目前可用于铀元素分析的电子探针分析标准样品极少,且缺乏与天然矿物成分、结构近似的标准样品。国际和国内已经制定了电子探针标准物质研制的规范(GB/T 4930—2008/ISO14595:2003),按该规范规定的方法研究了产于陕西光石沟铀矿床的晶质铀矿,结果表明:这些晶质铀矿晶形发育好,颗粒大,具备良好的纯度、均匀性和稳定性。随机选择30个颗粒进行均匀性检测,UO₂和PbO在95%的置信区间的平均浓度不确定度分别为0.275%和0.060%,具备非常好的均匀性;该晶质铀矿在电子探针电子束长时间(如360s)轰击下和在自然条件下存放,均具有良好的稳定性;采用五家实验室化学分析定值方法确定了该晶质铀矿的化学成分,并计算了不确定度,主量元素UO₂为(86.80±0.36)%,PbO为(4.80±0.07)%,其他元素也给出了参考值。综合以上研究结果:产于光石沟铀矿床的晶质铀矿满足GB/T 4930—2008关于电子探针定量分析标准样品的各项判据,是一个潜在的适用于铀矿物化学成分电子探针定量分析使用的天然矿物标准样品。

Guangshigou Uraninite:A Potential Reference Material for Uranium Minerals EPMA Quantitative Analysis

EPMA quantitative analysis is finished by measuring and comparing the characteristic X-ray intensity of element A in the sample to be measured with the characteristic X-ray intensity of A in reference materials,therefor reference materials is necessity to analyze the unknown samples.So far,there are few reference materials can be used in detecting U by EPMA,especially the natural reference materials with similar compositions and structures.According to the EPMA guidelines for the specifications of certified reference materials(GB/T 4930—2008/ISO 14595:2003)at home and abroad,we studied the uraninite from Guangshigou uranium deposit in Shanxi province and found that the uraninite samples have good crystalline morphology,large grain,and good purity,homogeneity and stability.30 grains were randomly selected for the homogeneity detection,the average concentration uncertainty of UO₂ and PbO are 0.275%and 0.060%respectively in 95%confidence interval suggesting.Very good homogeneity of the uraninite.The uraninite is with very good stability under the long time(such as 360 s)bombardment of probe electron beam and natural store condition for a long time.The chemical composition of uraninite was determined by chemical analysis and determination in five laboratories.We also calculated the uncertainty.The main element UO₂ is 86.80±0.36 wt%,PbO is 4.80±0.07 wt%,and other elements are also within the given reference values.According to the above study results,the Guangshigou uraninite meets the criteria of GB/T 4930—2008 and can be used as a potential nature mineral reference material for detecting the chemical composition of uranium minerals by EPMA quantitative analysis.