gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1961.032.252.05 Ages of Some Uranium and Thorium Minerals from East and Central Africa Darnley A. G. M.A., Ph.D., A.M.I.M.M., F.G.S. Horne J. E. T. M.A., F.G.S. Atomic Energy Division, Geological Survey of Great Britain Smith G. H. Chandler T. R. D. National Chemical Laboratory, Teddington, Middlesex Dance D. F. Preece E. R. Atomic Energy Research Establishment, Harwell, Berkshire 3 1961 32 252 716 724 Copyright © 1961, The Mineralogical Society 1961 Summary

The following ages determined by the complete lead method have been accepted for minerals from a number of localities: uraninite, Nkana, Northern Rhodesia, 522±15 m.y. ; brannerite, Kansanshi, Northern Rhodesia, 503±15 m.y. ; uraninite, Shinkolobwe, Katanga, 642±20 m.y. ; davidite, Mavuzi, Mozambique, 578±15 m.y.; monazite, Monkey Bay, Nyasaland, 597±25 m.y.; samarskite, north-west Kenya, 635±25 m.y. The significance of the results is briefly considered.