Analysis of uranium distribution in rocks by μ-PIXE

We examined distributions of U as well as P, Ca, Fe and Ti in rock samples collected at the Koongarra uranium deposit, Australia, using a micro-proton-induced X-ray emission (mu -PIXE) analyzing system developed in the TIARA facility of Japan Atomic Energy Research Institute (JAERI). The conventional scanning electron microscopy-energy dispersive X-ray specrometry (SEM-EDS) was also applied to identify a U-bearing phosphate as saleeite, and to examine the distributions of the above elements to clarify relative advantages of mu -PIXE. The advantages of mu -PIXE are as follows: (1) the spatial resolution of mu -PIXE, about 0.8 mum(2) is higher than that of SEM-EDS, about 7 mum(2) (2) the contrast of elemental maps by mu -PIXE is better than that by SEM-EDS, (3) mu -PIXE detection of U using its L-line gives more reliable U distribution when clay minerals containing potassium are present. It is concluded that mu -PIXE is one of the best techniques that allows U to be accurately analyzed and mapped in K-bearing minerals, using its L-line. (C) 2001 Elsevier Science B.V. All rights reserved.