Conventional and unconventional uranium deposits

Abstract

The history of uranium exploration illustrates that the concept of typical, or conventional deposits has been conditioned by the relative ease with which deposits could be most quickly discovered and produced, that were best able to satisfy the existing market. The concept has been less influenced by the true range of deposit types and their relative abundances, sizes and grades, than by the prevailing concept of that range. All the parameters of the complete range have not been recognized at any time. History also demonstrates that the type of uranium deposit considered “conventional” at any stage changed radically from stage to stage. The size of the uranium market has grown stepwise in quantum jumps punctuated by dormant intervals. The size categories were determined by the extent of use. When new uses for larger amounts developed, the initial attempt was to meet the demand by discovering more deposits of the “conventional” types and in the same areas. However, uranium geology was unable to satisfy quickly the new market, either because the “conventional” deposits of the former stage could not be replicated or because they were too small. Pioneer prospecting in regions theretofore considered unfavorable discovered new larger types of deposits. Thus, the earlier mined deposits were conventional only to their corresponding market, but not in the complete range of geological parameters. The changes from rich veins and radium market to sandstone impregnations and military market and then to “unconformity-related” masses and power market were so radical that at no stage should the truly conventional types of deposits be considered well known. Scrutiny of the status of uranium geology at any stage reveals that geological relations had been described which indicated the existence of new classes of larger ore deposits. However, their significance was not generally recognized, and they did not assist in the subsequent discoveries. The current analysis of unconventional uranium deposits was initiated with the goal of recognizing the next generation of “conventional” deposits in the data mass accumulated from the sandstone impregnation era. Unfortunately results were still unpublished when the unconformity-related deposits became well established and the uranium market again declined. Nevertheless, the descriptions should be valuable if the established evolution trend continues, as suggested by recognition of a still newer and larger type represented by Roxby Downs.