Government-led prospecting for economic uranium mineralisation, conducted in the Yankalilla area during June-September 1954, has consisted of detailed Geiger counter radiometric survey traversing of the outcropping Archaean basement rocks at 1 chain intervals, and assaying of grab samples of radioactive rocks collected at 22 anomalous sites. Most of the radioactive mineral occurrences have given rise to thorium series decay products, with only a few uranium series decay products noted. It appears that any substantial radioactive mineralisation will only be found at depth in the basement, with the majority otherwise existing as disseminated mineral inclusions in pegmatite, as judged by the nature of the surface occurrences found.