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The geological and environmental controls upon the pattern of increasing dune redness inland in the Namib Sand Sea are investigated using mineral magnetic measurements, satellite imagery and dithionite extractable iron. Results suggest whole grains or inclusions within grains dominate the iron oxide assemblage but the sediment colour is more strongly influenced by a second component which consists of haematite within the grain coatings. The magnetic data suggest that source materials exert at least a partial control on dune colour in this field setting. Evidence for the influence of other factors (e.g. age and climatic gradient) is also present. (C) 1997 Elsevier Science B.V.