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High levels of uranium and its radioactive progeny like radium is normally associated with phosphate mining. In Situ gamma ray spectroscopy as a survey tool has been successfully applied to assess radio-nuclide concentrations in various geographical environments. A transportable and robust gamma ray detection system (GISPI) was therefore employed to determine the concentrations of naturally occurring radionuclides at a disused phosphate mine on the West Coast of South Africa. The concentrations of radium, thorium and potassium were measured and plotted. The measurements showed fairly high concentrations with medians of 320 Bq/kg for Ra-226, 64 Bq/kg for Th-232 and 390 Bq/kg for K-40. The highest concentrations were however confined to specific areas of the mine. The effective dose due to gamma irradiation for the various areas of the mine was also estimated and the highest estimated level was 0.45 mSv/y. The article finally draws conclusions as to the origins and impact of the radiation. (C) 2015 Elsevier Ltd. All rights reserved.