陨石的放射性比活度及其成因分析

The specific activity of radioactivity for meteorites and its genesis

近几年国际陨石市场发展迅速,陨石类饰品以不可替代的独特优势备受公众瞩目,多数消费者普遍存在陨石辐射危害人体健康的误解和疑虑。本文通过针对性测试可作为饰品原材料的铁陨石、橄榄陨铁、普通球粒陨石和玻璃陨石的块体样品,以及普通球粒陨石粉末样品的放射性元素(^(226)Ra、^(232)Th和^(40)K)比活度,获得这些样品的放射性比活度数据。结果表明,所检测陨石样品的放射性比活度和内外照辐射指数(I_(Ra)和I_(γ))均低于人体皮肤放射性安全标准,同时低于和田玉和祖母绿等传统宝玉石;而玻璃陨石的放射性比活度略高于作为对比的宝玉石,但低于人体安全标准。通过对所检测样品的矿物组合和化学组成等指标对比分析,认为陨石中具有高浓度放射性元素的矿物含量极低,宇宙射线不能导致陨石放射性增加,玻璃陨石相对较高的放射性比活度主要由源区岩石中残留含高放射性元素矿物引起。

The international meteorite market has developed rapidly in recent years.Meteorite jewelry has attracted the attention of the society for its unique and irreplaceable advantages.Most consumers generally have misunderstandings and doubts for the harm to human health caused by meteorite radiation.In this paper,based on the specific tests,the specific activity data of radioactive elements (^(226)Ra,^(232)Th and^(40)K) for bulk samples of iron meteorites,pallasites,ordinary chondrites and tektites,which can be used as jewelry materials,as well as powder samples of ordinary chondrites have been obtained.The results show that the specific activity of radioactivity and internal and external radiation indexes (I_(Ra)and I_(γ)) for the tested meteorite samples are lower than those of the radiation safety standard to human skin,and lower than those of the traditional gems and jades such as Hetian jade and emerald.The specific activity values of radioactivity for tektites are slightly higher than those of the gems and jades as a comparison,but lower than that of the safety standard to human body.Through the comparative analysis of mineral associations and chemical compositions for the detected samples,it is concluded that contents of minerals with high concentrations of radioactive elements in meteorites are extremely low,and cosmic rays cannot lead to the increase of radioactivity of meteorites.The relatively high specific activity values of radioactivity for the tektites is mainly caused by the residual minerals containing high radioactive elements in the source rocks.