Exploration for possible economic syngenetic/stratiform or epigenetic/hydrothermal base metals and gold hosted by Early Cambrian and older Adelaidean rocks in the Angepena area initially comprised the conduct of reconnaissance 1:50,000 scale geological mapping and rock chip sampling of the Mount Hack Syncline and of the abandoned Angepena gold diggings, plus gravity and ground magnetic surveying of part of the latter, and a geochemical and petrological assessment of core samples taken from stored drill core of Carpentaria Exploration Co.'s Angepena DDH 6. A maximum surface value of 2.6 ppm Au was obtained by analysing a bulked sample of the target ironstone horizon outcropping at Angepena, the rock samples coming from 1.5 km along strike to the west of CEC's diamond drillhole site. 250 gravity and 668 magnetic readings were made on a 200 m x 10-50 m grid designed to try to located an inferred massive buried body of pyrite/pyrrhotite and barite-rich diapir-related material that might carry significant gold. However, no significant gravity or magnetic anomalies were detected. Within the Mount Hack Syncline, which is a narrow, 40 km long east-west fold structure much disturbed by later faulting and diapirism, Amoco discovered near Puttapa Springs only one small patch of zinc-anomalous, probably gossanous carbonate rock within the dolomitic Wilkawillina Limestone. Subsequent work concentrated on more detailed 1:20,000 photogeological and 1:2500 scale geological mapping of the informally named Angepena Ironstone unit, which is thought to be the source of the historically mined alluvial gold occurrence, plus exploratory RAB drilling (36 holes for a total penetration of 984 m) to probe into it at depth beneath the better surface gold anomalies. The best downhole assay result was 0.6 ppm Au over 2 m, directly beneath the surface 2.6 ppm anomaly. The host unit was shown to be a 3-10 m wide linear band of ferruginised rock that extends continuously over 4 km. It is predominantly a massive calcareous goethite-limonite rock having strongly manganiferous and ferruginous sections, that lies conformably immediately below the base of the Balcanoona Formation, and above probable tectonically emplaced diapiric material. Besides carrying anomalous gold and manganese, there is a likely association also with elevated barium (to 5450 ppm Ba) and arsenic (to 1050 ppm As) values. However, similar geochemical analysis of the surrounding Adelaidean rocks done by Amoco failed to indicate any presence of anomalous gold or base metals. The revised interpretation of the ironstone unit, based partly on mineragraphic evidence of contained microscopic boxwork structures after contact metamorphic minerals, is that it represents a later weathered and ferruginised contact zone between a diapiric mass and a low grade metamorphosed impure dolomite within the Balcanoona Formation.