During early 1970 BHP investigated an area on Roopena Station, 20 miles north-northwest of Whyalla, for possible late Meso- to early Neoproterozoic stratiform copper associated with the basal Adelaidean unconformity. Previously, interesting minor occurrences of copper sulphide, grading to 0.41% Cu over 6 feet below 463 feet depth, and 0.25% Cu over the depth interval 478-490 feet, had been found on fracture and joint surfaces in folded and brecciated Neoproterozoic ?lower Callanna Group shales and carbonaceous siltstones near their basal unconformity with the Lower Carpentarian Moonabie Formation, by SA Department of Mines stratigraphic diamond drilling carried out in 1967. As well, traces of copper sulphides and galena had been recorded in surface samples of the Roopena Volcanics, the inferred oldest Neoproterozoic unit, which occupies much of the central and eastern part of the study area. The work undertaken by BHP has consisted of geological mapping and a geochemical orientation stream sediment survey, followed by the drilling of six percussion holes totalling 1439 feet that were aimed at intersecting the copper-bearing horizon at relatively shallow depths, besides providing information about the distribution of the lower Callanna beds. One of the drillholes, RP3, was also sited to test the possibility that remobilisation of sulphides had occurred within the Roopena Fault zone. 170 stream sediment samples (10 per square mile) of minus 80 mesh size fraction gave only anomalous Pb, Zn and Cu that is seen as reflective of the outcropping rock types. A few spot anomalies for Ag, Co and Cr are explainable by the presence of late stage Gawler Range Volcanics dykes, the slightly mineralised sericitic and chloritic Roopena Fault zone, and probable chromites shedding from heavy mineral laminations within the Moonabie Formation. The maximum thickness of the lower Callanna Group in the study area is now believed to be in excess of 200 feet, based on the drill intersection in hole RP5, which comprised predominantly a slightly pyritic shale with arkosic interbeds and some basal conglomerate bands. However, interbedded andesitic lava flows found within this shale sequence in both holes RP2 and RP4 suggest that volcanic activity was penecontemporaneous with, and not subsequent to, early Neoproterozoic sedimentation in this area. Minute grains of chalcopyrite associated with haematite grains occur in fractured Moonabie Formation quartzite from around 300 feet depth on the Roopena Fault zone, in hole RP3. No other Cu sulphide was seen in the latest drilling. AAS analyses for Cu/Pb/Zn on cuttings samples from all six holes gave background values of the order of 100 ppm, with maxima of 1000, 1200 and 500 ppm respectively. A widespread stratiform distribution of very fine-grained (0.002-0.001 mm) pyrite in amounts less than 1%, throughout the lower Callanna shales, implies a syngenetic origin for this mineral. It is suggested that the trace copper sulphide is also of syngenetic origin, and that it has subsequently been remobilized in the zone of groundwater circulation, where an acidic environment would have existed owing to the weathering of pyrite. Preferential redeposition of chalcopyrite appears to then have been subject to both chemical and structural controls, mostly favouring slightly carbonaceous shales that have undergone limited fold/fracture deformation. Because the lower Callanna sequence at Roopena is only very slightly deformed, as part of a broad north-west trending syncline, the potential for finding significant mineralisation formed according to this model appears to be poor. No method, other than extensive drilling, is seen as likely to provide any more conclusive result in the Roopena area. Electrical geophysical methods were considered, but cannot be expected to indicate significant anomalies beneath a thick cover of volcanics and/or pyritic sediments.