Continuing exploration of the geochemically anomalous (35-210 ppm Ni) Lower Proterozoic basement rocks previously identified by Kennecott at Blackfellow Hill has consisted of first laying out a 10,000' x 7200' prospect grid, before conducting soil sampling, ground magnetic surveys and detailed geological mapping based on newly acquired 1:40,000 scale airphoto mosaics. This work defined a sheared mafic / ultramafic body that is intruded between two banded iron formation (BIF) horizons which are associated with several steep-sided and discrete magnetic anomalies. The latter anomalies were thought to reflect also a later, major NNE-trending transcurrent fault which has bisected the prospect area and dragged out the limbs of the original tight synclines in the BIF sequence. A programme of truck-mounted deep power auger drilling (152 holes to a maximum depth of 54 feet, put down at approximately 100' intervals) was performed during the period February-September 1970, largely in the north-eastern sector of the Blackfellow Hill prospect grid, to probe beneath deep transported soil and travertine limestone cover and to obtain more representative, less weathered bedrock samples of the target intrusive body. This drilling more accurately defined the zone of nickeliferous rocks, which covers an area of about 5000' x 4000', being composed of tremolite - chlorite - phlogopite - montmorillonite altered material that probably is derived from regional metamorphism of an original mafic / ultramafic intrusion. The contacts with the deformed BIF metasediments on either side are characterised by elevated copper values, however, the drilling did not find any significant magmatically differentiated nickel or copper mineralisation associated with the intrusion's lower contact, although chromium values from here are generally high (500-3000 ppm Cr). In other work undertaken to search for additional ultramafic intrusive rocks in the Mulgathing region, 10 significant aeromagnetic anomalies were picked from the data of the 1957 SADM regional survey and accurately located by ground magnetic traversing. Two of the anomalies were seen to have surface float of drusy chalcedony and silicified serpentine lying adjacent to BIF subcrop, as at Blackfellow Hill, which could indicate a buried mafic / ultramafic intrusion, so they were also sampled by power auger drilling. No base metal assay results of note were obtained due to poor drill penetration ability at the time, although apparently lateritised, carbonate-altered mafic rock was recovered in the lowermost drill cuttings samples. There is some evidence to suggest that goethite bands found at Blackfellow Hill and at Skuse Hill may be completely oxidised sulphide lenses, and therefore it has been recommended that these features be tested at depth by future percussion drilling.