Applicability of radiometrics and the portable gamma ray spectrometer was tested over parts of the southern Gawler Craton. Use of total count and separate counts for potassium, uranium and thorium helped to distinguish lithologies e.g. to locate hidden contacts between Miltalie Gneiss and Warrow Quartzite. Rocks giving high readings include anatectic portions of the Carnot Gneisses, pegmatites, aplites and tabular feldspar granite of Mount Hope and Point Drummond. Uranium concentration occurred at a later magmatic stage.