Petrographic study of a selection of rocks taken from major horizons recognised at the Myponga uranium prospect has allowed discrimination of a confusing suite of rocks into several intelligible groups on which future field mapping may be based. It is apparent that albitization by metasomatic means is as important as the structure in controlling localization of the ore. The lodes are now known to contain pitchblende, gummite, beta-uranotil (a mineral related to uranophane), and possibly meta-autunite. Albite occurs in direct association with pitchblende and its alteration products. It is suggested that mapping of mineral lineation may help considerably in a final appraisal of the role played by structure.