Radiation damage in sulfides: Radioactive galena from burning heaps, after coal mining in the Lower Silesian basin (Czech Republic)

The isotopic composition of lead (²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb, and ²¹⁰Pb) in a recently formed galena from burning heaps after coal mining in Radvanice, Markoušovice, and Rybníček, the Lower Silesian basin, Czech Republic, was studied in detail. ²¹⁰Pb activity in galena varied from 135 ± 9 to 714 ± 22 Bq/g and calculated integral doses ranged from 2.21 × 10¹¹ to 6.11 × 10¹¹ α/g. The radioactivity of the galena causes micro-deformations in its crystal structure as indicated by the Williamson-Hall graphs, showing that the level of micro-strain depends on the length of time that galena samples were exposed to the radiation. However, the crystal structure of galena is affected very inhomogenously; according to TEM investigations there are domains of fully crystalline, polycrystalline, and fully metamict galena within one crystal. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the isotopic composition of the studied galena. The stable isotope ratios of Pb varied for ²⁰⁷Pb/²⁰⁶Pb from 0.8402 to 0.8435 and for ²⁰⁸Pb/²⁰⁶Pb from 2.0663 to 2.0836. The average ratios ²⁰⁷Pb/²⁰⁶Pb = 0.8312 and ²⁰⁸Pb/²⁰⁶Pb = 2.0421 were obtained for coal from the same localities. These isotope ratios show that there is no isotopic fractionation taking place during the coal burning and subsequent galena crystallization from hot gases.