In September and December 2004 Mithril Resources completed 53 vertical aircore and reverse circulation drillholes on Exploration Licence 2842 as part of the SA Government's PACE Initiative 'Theme 2' collaborative drilling programme involving PIRSA Minerals and Energy Div. The 2079 m of drilling tested the development of anomalous nickel enrichment in the weathering profile of the Harris Greenstone Domain ultramafic rocks of the Gawler Craton, a geochemical characteristic first recognised during Mithril's exploration in June 2004 at the Mullina prospect, located approximately 15 km south-east of Tarcoola, when five RC drillholes were put down to test a 4000 ppm surface nickel anomaly detected by sampling magnetic lag. Besides further investigating the Mullina occurrence, the drilling also addressed two other, largely untested portions of the Harris Greenstone Domain subcrop area, at the Mullina West and Moolkra prospects. At the Mullina prospect, the PACE drilling delineated a nickel enrichment halo extending over a 900 m west-east strike length and a 150 m north-south width, with downhole Ni values commonly averaging above 1500 ppm over a 30-35 m thick interval, and reaching up to 7000 ppm (in 3-metre composite drill cuttings samples) in a zone central to holes THAC029 and THAC026. Observed similar degrees of associated cobalt and iron enrichment in the regolith have helped to geochemically characterise the strong nickel anomalism as being derived from an (as yet) unlocated sulphide source. The 'footprint' of this type of enrichment and metal dispersion up through the weathering profile is here clearly several magnitudes larger, in projected-to-surface area, than its nickel sulphide point source, but its recognition as a locally cogent geochemical gradient now generates useful vectors that will contribute to exploration models and prospect development. The Lake Harris Komatiite was the primary unweathered rock unit intersected at the Mullina and Mullina West prospects, whereas metapyroxenite and metagabbro were intersected at Moolkra.