In a search for East Alligator River - type metamorphic uranium deposits, a review of previous geophysical data plus the conduct of ground and airborne radiometric surveys disclosed a number of anomalies in an area on central Eyre Peninsula extending from Mount Messenger to Secret Rocks. However, following ground-truthing of the more prominent anomalies through bedrock and groundwater sample geochemical analyses, plus the drilling of 3 percussion holes (total 300 m) to test for possible concealed sources of radioactivity, the underlying gneissic rocks are now considered not to be prospective for uranium, being instead characterised by a high level of thorium, with associated secondary radium-in-manganese concentrations (having up to 15,000 counts per second) localised in areas of groundwater discharge at the surface.