Gamma-ray spectroscopic and PIXE analysis of selected samples from the phosphorite deposits of Northwestern Saudi Arabia

Phosphorite deposits from northwestern Saudi Arabia were analyzed by natural radioactivity measurements to detect the presence of radioactive elements. PIXE was used to obtain an average elemental composition of these deposits. From the analysis of radiations from 238U, 232Th and 40K isotopes, the samples were found to contain U, Th and K in concentrations up to 130 ppm, 30 ppm and 2.5 wt%, respectively. PIXE showed the presence of a number of trace elements such as Ca, V, Cr, Fe, Ni, Cu, Zn, As, Sr, Y and U in concentrations ranging from a few ppm to several hundred ppm. The occurrence of these radioactive and non-radioactive elements are discussed for their geological significance in the phosphorite deposits.