Potential of thorium-bearing minerals from an abandoned radioactive mineral mine in Neluwa, Sri Lanka

Abstract

Sri Lanka hosts historically significant thorianite deposit in the Neluwa region, which may still contain valuable thorium-bearing minerals. Renewed global interest in thorium for advanced clean energy technologies, higher technological applications, and national economic development underscores the importance of this study. This research investigates the presence and distribution of thorium through mineralogical and geochemical analyses of the abandoned mine. Sampling involves surface sediment samples, pegmatitic rock, subsurface sediments, and plants. A multidisciplinary approach for field inspections including radiometric surveys, heavy mineral separation using bromoform, microscopic analysis to identify thorianite crystals and elemental analysis using Inductively Coupled Mass Spectrometry (ICP-MS) to quantify targeting thorium. The results provide insight into zones with potential for thorium, significant surface sediments, subsurface sediments, rock, and plants. The findings suggest that the Neluwa abandoned mine represents a significant natural trap for thorium-bearing heavy minerals, particularly in subsurface sediments. While mineralogical and geochemical evidence supports resource potential, the observed bioaccumulation underscores environmental and health risks. This study highlights the value of integrated geochemical and mineralogical approaches in evaluating radioactive mineral anomalies.