Large sedimentary phosphorate deposits are unlikely to be found in the Cambrian on Fleurieu Peninsula or the southern part of Yorke Peninsula. Further exploration of the phosphatic Brighton Limestone and Saddleworth Formation type of facies should be made in the Proterozoic rocks. Proterozoic, and possibly Cambrian phosphorates are associated with anomalous radioactivity. A vehicle-mounted scintillometer survey of the Orroroo district indicates that this method could be useful in defining areas for testing for phosphate, provided Tertiary lateritic cover is absent, and Recent and Quaternary alluvium are thin. The Tarcowie Siltstone and the Tapley Hill Formation (Tindelpena Shale Member) produced anomalies which should be checked and tested. Phosphate in above-average concentrations occurs in three main lithofacies types in the Cambrian and Proterozoic: (1) Impure calcareous sandstone, e.g. the top of the Mt. Terrible Formation and below the Brighton Limestone (2) Rubbly impure limestone e.g. the centre of the Sellick's Hill Limestone (3) Calcareous nodular concentrations in shale e.g. he Heatherdale Shale