Placer deposits

Abstract

Editorial note: A meeting on ‘Placer deposits’, convened by Dr D. G. Sutherland (Placer Analysis Ltd, Edinburgh) and Dr I. Reid (Birkbeck College, London) on behalf of the British Geomorphological Research Group and the Institution of Mining and Metallurgy was held at the Geological Society. Burlington House on 15 November 1984. Drs Ian Reid and Donald G. Sutherland have provided the following introduction to the published papers: Placers have always been important sources of both economically and industrially useful minerals. Much of the impetus given to colonization of the North American western states and the Alaskan Pacific coast came from the riches promised by placer gold. Fossil gold placers currently provide nearly half of the Republic of South Africa’s commodity export earnings. Alluvial diamonds are important to the economies of several other African states, including Sierra Leone, the Central African Republic, Zaire and Namibia. Placer tin provides Malaysia and Thailand with about 10% of their exports. The contribution of placers to world mineral production (by weight) ranges from 34% for diamond to 69% for gold. Tin placers yield 49%, while 69% of titanium comes from sedimentary sources. Despite a slight decline in their relative importance over recent years, there has been a reawakening of commercial interest in placers as potential sources of mineral wealth. However, this interest requires direction. It cannot rely upon the chance discoveries that typified historical enterprise, if only because modern exploitation is highly capitalized and involves considerable investment. This is where geomorphology makes a substantial contribution