During the late 1990s, company exploratory drilling of the Harris Greenstone Belt in the central Gawler Craton, south of Tarcoola, revealed a package of previously unknown, shallowly buried komatiite lava beds with a strike length in excess of 350 km that are prospective for massive Ni-Cu sulphide mineralisation. In late 2002, Minotaur Resources leased two blocks of ground covering 1050 square km in the vicinity of Talia Hill, that spanned more than 120 km of strike extent of the Harris Greenstone Belt, to explore for such mineralisation. In June 2004, its nickel - focussed spinoff subsidiary Mithril Resources tested five high magnesia and magnetic targets for nickel mineralisation by drilling a total of 14 inclined RC holes totalling 934 m. These targets had been delineated by interpretation of aeromagnetic data, supplemented by magnetic lag geochemical sampling, and the drilling was aimed at intersecting the basal contact of the Lake Harris Komatiite sequence. This part of the unit was successfully sampled on four of the drillhole traverses. The best single assay for nickel was 4000 ppm Ni in hole THRC05 over the depth interval 16 - 20 m, while the second best assay was 3900 ppm Ni in hole THRC04, from 12 - 16 m depth. The best mineralised intercepts included 12 m @ 3700 ppm from 12 m depth in THRC04, and 16 m @ 3100 ppm from 12 m depth in THRC05. All of these intercepts were made within moderately weathered ultramafic rock at the Mullina prospect. The best single gold assay was 160 ppb Au (average) from the depth interval 32 - 36 m in hole THRC04, and the best platinum assays were 25 ppb Pt in each of THRC03 (8-12 m depth); THRC05 (16-20 m depth); and THRC14 (16-20 m depth). The coincident nickel - copper - cobalt anomalism was interpreted to indicate a proximal sulphidic origin for the metal enrichment dispersed within the weathering profile. During September and December 2004, Mithril Resources completed another 23 RC and 30 aircore drillholes along 200 m spaced north-south traverses (for total penetrations of 711 m and 1368 m respectively) to further test the prospectivity of the Lake Harris Komatiite, with the cost of this drilling partly subsidised as part of PIRSA's PACE Initiative Theme 2 collaborative drilling programme (through project DPY1-10). Most of these drillholes tested the areal development of nickel enrichment in the weathering profile of the Lake Harris Komatiite at the Mullina Prospect, located approximately 15 km south-east of Tarcoola. Drilling was also conducted over two other untested portions of the Harris Greenstone Belt, with 3 RC and 10 aircore holes drilled on the Mullina West target and 13 aircore holes drilled on the Moolkra target. At the Mullina prospect, the drilling delineated nickel enrichment over a 900 m west - east strike length and 150 m north - south width, with nickel concentrations above 1500 ppm Ni and reaching up to 7000 ppm Ni (in three metre composite drill samples) in a zone central to holes THAC029 and THAC026. The Lake Harris Komatiite was also encountered at the Mullina West prospect, whereas metapyroxenite and metagabbro were encountered at Moolkra. A ground TEM survey was completed over the nickel enrichment zone at the Mullina prospect, and a steeply dipping moderate to late time conductor, with a strike length of > 400 m and a moderate easterly plunge, was identified. In December 2005, again with PACE Initiative funding assistance through project DPY2-42, Mithril completed 5 inclined RC percussion drillholes totalling 682 m on three 100 m spaced traverses at the prospect, to test this conductor. The drilling encountered a sequence of ultramafic rocks which are interpreted to be komatiites that have sheared contacts with gneissic rocks. Sulphides (dominantly pyrite) were commonly identified in the ultramafic rocks, but only in quantities of less than 2%. Two 8 m thick intervals grading over 0.5% Ni were intersected in weathered ultramafic rocks. Drillhole THRC-069 intersected rock containing up to 15% pyrite over a 2 m thick zone which graded 0.44 g/t Au. It is probable that this pyritic horizon is the source of the surface conductor, although downhole EM failed to detect any significant offhole conductive bodies. During the 2006 licence year Mithril also negotiated an agreement with the Far West Coast Native Title Claim Group and completed a site avoidance heritage survey in the southern portion of EL 2842, within the Yellabinna Nature Reserve, over a number of gravity anomalies which had been identified from PACE programme 2005 regional gravity data as coinciding with the western extension of the Yerda Shear magnetic trace. This survey was successful in clearing two sites for proposed drilling and an access route into these sites. Prior to undertaking the heritage survey, Mithril had gained the approval of the Department of Environment and Heritage to its formal request to employ "Drilling/use of declared equipment" within this portion of Yellabinna. Difficulties in obtaining a suitable drilling rig delayed the subsequent drilling at Yerda prospect until mid-September 2009, when 2 vertical RC percussion holes for 207 m total penetration were completed to test for possible iron oxide - associated copper-gold mineralisation, but without success. Both drill holes intersected variably metamorphosed mafic rocks at shallow (<10 m) depths beneath a thin sand cover. As the gravity anomalies' sources had been modelled to lie at 150-200 m depth, the presence of the shallowly buried mafic rocks easily explained the gravity response, and no further work was recommended on these targets. At the end of the eighth licence year it was decided to fully surrender tenure, as in the licensees' opinion no significant komatiitic nickel sulphide or IOCG targets remained untested.