The discovery in July 1970 of a strong surface radioactive thorium anomaly emanating from outcrop near Uno Homestead, 48 km north-west of Iron Knob, which was made by a Japanese company's geophysical prospecting party, prompted the leasing of the surrounding ground to allow investigation of the economic potential of the source mineralisation, which appeared to be Mesoproterozoic sedimentary uranium hosted within the Corunna Conglomerate over at least a 610 m strike width of exposed beds. Subsequent exploration work comprised a 400 linear km car-borne ground radiometric survey, geological mapping, rock chip, stream sediment and soil and lake bed sediment sampling, radiometric anomaly trench logging and sampling, groundwater sample analyses, sedimentological and mineragraphic studies of radioactive sediments, and the traverse drilling of 5 diamond holes totalling 722.7 m, to test un-oxidised portions of the eastwards-dipping target formation down to a depth of 244 m. Drill core sample assay values to a maximum 200 ppm U3O8 and 3300 ppm ThO2 were returned, with downhole radiometric log anomalies, peaking at 21,000 counts/minute, indicating that the mineralised beds (pebble-granule conglomerate and grey sandstone) are from 2 to 7 m thick. The anticipated likely increased enrichment, with depth, of uranium relative to thorium, was not seen, so additional, deeper drilling of the mineralised beds is planned, to seek possible ore-grade uranium. The surface Th radiometric anomaly, ranging from 50-2100 counts/hour on a background of 5-10 cph, was able to be traced for 14 km along the Uno Range in the same horizon, which appears to be about 40 m thick.