Studies completed on the Damaran pegmatitic leucogranites, intruded as dykes and sheets in the vicinity of the Rössing Uranium Mine, indicate that they are derived from the residual crystallization products of a late Damaran granitic pluton intruded into the lower formations of the Damaran cover rocks transecting an earlier ductile shear zone generated during orogenic transpression. These structural pathways have acted as controlling conduits for later transtensional granite emplacement and uranium mineralization. The fluid-rich pegmatitic leucogranites in the cover rocks are therefore considered to be fractionated products of granitic magma, generated in a transtensional environment as a consequence of orogen extensional collapse following oblique collision between the Congo and Kalahari cratons. This transtensional tectonic setting generated a wide range of leucogranite normative compositions, but the majority of the leucogranites at the Rössing Mine are pegmatitic alkali-leucogranites (alaskites) exploited economically for their uraninite and beta-uranophane. All the Rössing leucogranites have anomalously low Th/U ratios. The mineralization at the Rössing Mine can be viewed as successive concentrations of U relative to Th related firstly to a primary magmatic process of pegmatite formation; secondly to hydrothermal redistribution, and finally to supergene enrichment. The tripartite series of geochemical processes has caused the decoupling of uranium and thorium concentrations so that U is considerably enriched relative to Th in the ore reserves used for mining. Such natural geochemical changes have considerable benefits to the workforce at Rössing. Health hazards from uranium and thorium are not as serious as those found in other uranium deposits where Th/U ratios are closer to the natural crustal abundance of 4 to I.