Riviera Tungsten — A Discovery Case History

Exploration & Mining Geology, Vol. 3, No. 4, 1994

P.W.A. WALKER, Anglo American Corporation of South Africa Limited, c/o Erongo Mining & Exploration Company Limited, Windohoek, Namibia

The Riviera tungsten occurrence in the Cape Province of South Africa was discovered in October 1979 as a result of stream-sediment panned concentrate sampling. The Cape age granite and late Precambrian Malmesbury Group carbonates and chlorite schists which it intrudes and which host the mineralization are covered by between 10 m and 30 m of Tertiary/Recent alluvium and clay. The scheelite/powellite and molybdenite mineralization occurs in a greisenized granite cupola with an overprint of porphyry-type alteration as well as in minor skarns. The ore reserve is estimated to be 46 million tonnes at an average grade of 0.216% WO3 and 0.020% Mo. The deposit is uneconomic at current tungsten prices.