Abstract
Clays are among the most important industrially used minerals. Three potential clay mineral mining sites in Saudi Arabia were chosen, and 21 clay deposit samples were collected. The activity concentrations (average +/- standard deviation) of the naturally occurring radioactive materials (NORMs), U-238, Ra-226, Th-232, Ra-228 and K-40, were 49 +/- 20, 47 +/- 23, 34 +/- 11, 40 +/- 20 and 751 Bq kg(-1), respectively. The radiation dose assessments (e.g., absorbed dose rate, nGy h(-1); effective dose equivalent, mu Sv y(-1); and effective dose rate due to dust inhalation, mu Sv y(-1)) and hazardous indices (e.g., radium equivalent [Ra-eq] value, external hazardous index [H-ex], internal hazardous index [H-in] and representative gamma level [I-gamma]) were calculated. The wide variations in the activity concentrations of the NORMs according to sampling region could be due to the origin of the geological formation and the geochemical behaviour of the NORMs. Based on calculated hazardous (external and internal) indices, there were no expected radiological hazardous impacts of using clay deposits as building materials.