Phosphatized oolitic limestone and sandstone occur within arenaceous carbonates at the top of the Tapley Hill Formation, at or near the Brighton Limestone contact on the Fleurieu Peninsula and in similar stratigraphic, sedimentary setting between Burra and Orroroo. Petrological studies indicate phosphate occurs as microcrystalline apatite replacing ooliths and matrix in oolitic limestones, or as cement in siltstone and intraformational breccia. Similarity with the Russian Karatau Basin phosphorite is noted, and implications for exploration of similar deposits in SA considered.