An area surrounding Beltana in the Flinders Ranges, which is known to contain low level base metal mineralised Adelaidean and Cambrian sedimentary rocks and diapiric intrusive structures, has been prospected by a combination of photogeological studies and direct field mapping. Regional geochemical sampling of stream sediments, plus chip sampling of selected beds and any limonitic zones, was also undertaken to cover all outcrops of potentially mineralised stratigraphic units. Geological maps were prepared of certain areas of particular interest, namely the Muckatoona and Mount Bayley copper mines. Outcrops containing up to 52% zinc as the silicate willemite, and up to 14% of the lead arsenate mineral hedyphane, were discovered in an area east of Puttapa Railway Station where the Lower Cambrian Ajax Limestone is closely associated with intruding diapiric material within an extensively faulted zone. The zinc enrichment is contained in a red, dolomitic and slightly manganiferous variant to the Ajax lithology which has been recrystallized and altered by presumed mineralised ground water solutions passing along fault planes. A detailed geological map of the willemite deposit has been prepared at a scale of 1 inch to 40 feet.