A complicated basement sequence comprising Palaeoproterozoic Willyama Supergroup metasediments, intrusive igneous rocks and volcanic rocks, plus Mesoproterozoic granitoids and associated mafic dykes, which occupy the south-western corner of the Broken Hill tectonic domain in an area centred about 35 km south-east of Olary near Radium Hill, has been explored for possible economic Olympic Dam and Cloncurry style epithermal/hydrothermal iron oxide - associated copper-gold deposits and for Broken Hill type (BHT) stratiform/stratabound lead-zinc-silver deposits. Under the management of exploration alliance co-venturer BHP Billiton Ltd, who was seeking to identify any large scale (~100 Mt) silver-lead-zinc deposits in the southern Curnamona region, initial work on the licence followed a “collate - fly - drill” exploration methodology, with drilling assured subject to the identification of suitable airborne EM targets. During March 2001 BHP acquired an airborne EM survey totalling 1248 line km across the tenement, along 150 m spaced SE-NW orientated flight lines with a sensor mean terrain clearance of 120 m, which delineated several targets for follow-up. However, trial drill tests completed during November 2001 at the two most significant AEM anomalies, the Dey Hill and Ballara prospects, surprisingly yielded negative results, when RC hole BRC01 was drilled vertically to a TD of 179 m, and vertical diamond hole DH01 (RC precollared to 209 m) was terminated at 367.7 m depth, both without encountering mineralisation or any probable conductive source. A subsequent independent review of the AEM data highlighted deficiencies in the EMFLOW processing procedure, and the re-evaluation of individual AEM flight line channel plots then identifed a robust AEM anomaly 600 m in length near Open Dam, that was not identifiable from the processed conductivity depth images. When followed up with ground EM, this feature, designated BHT001, returned a strong bedrock response. It lies on the southern margin of a prominent gravity ridge, known to correspond along strike to outcropping BHT lode rocks. Almost from the outset Minotaur Exploration was of the view that BHP's exploration paradigm applied to Bonython Hill, centered on airborne geophysical assessment of complex bedrock located under areas of cover, appeared to be unacceptably high-risk. It believed that BHT mineralisation is well constrained by its unique gravity, magnetic and geological discriminators, and consequently, proposed that further work in the Curnamona Province should place more emphasis on detailed ground gravity and moving loop ground EM surveys over the defined target areas, rather than adhering to the blanket airborne EM approach. Serious doubts as to the source of many of the AEM responses resulted from the discovery of a single outcrop of graphitic schist the size of a tabletop in close proximity to a prominent AEM anomaly and known BHT horizon. A series of shallow air core drill traverses, and ground auger work where applicable, was undertaken in an attempt to demarcate the extent of graphitic units and to identify zones of potential BHT alteration (i.e. garnet sandstone, amphibolite, tourmalinite etc.) In total, 123 aircore holes were drilled along 9 traverses during August 2001, for a total penetration of 3367 m. This work eliminated 3 priority one AEM targets due to the presence of graphite. Nevertheless, weakly developed BHT alteration comprising garnetisation and/or tourmalinisation, with rarer Fe/Mn oxides, amphibolites and anomalous geochemistry, was recorded at six localities. During February-March 2001 Minotaur performed detailed, 1:10,000 scale geological mapping on EL 2788, which included field checking of the recently compiled MER 1:40,000 scale Radium Hill map plus the re-mapping of all BHT lode outcrops, Broken Hill Group strata, and rocks overlying the Dey Hill aeromagnetic anomaly. Outcrop is generally poor, with approximately 95% of the tenement covered by shallow Quaternary and Tertiary cover. However, extensions of the Broken Hill Group strata under cover were confidently interpreted from the regional aeromagnetic data, and a stratigraphic interpretation constructed. The detailed mapping identified four partially outcropping lode horizons along a corridor of Broken Hill Group strata extending for more than 12 km. These horizons seen at Dey Hill, Tepco, Mail Run and Toms Dam, typically comprise quartz-garnet-iron and manganese - rich lithologies, but granular gahnite was also found at Toms Dam and Dey Hill East. Rock chip sampling returned best assay values of 4.2% Zn, 2.0% Cu, 0.65% Pb, 2.3 g/t Au and 9 g/t Ag. A trial auger programme of regolith geology / geochemical sampling was undertaken during the field mapping exercise. Cover sequences throughout the region comprise remnant Pleistocene to Tertiary clay sand and gravel ranging from several meters to 50 m in thickness. These beds in turn are overlain by 1-4 m of recent Quaternary colluvium. Subcrop areas in the SW of the tenement are generally only blanketed by shallow Quaternary soils. The transported sequences uncomfortably overly partially weathered basement. It appeared to Minotaur that any deep saprolitic development of the basement had been stripped prior to deposition of younger Pleistocene -Tertiary sequences. Discriminant function analysis was applied to the Bonython Hill tenement regolith geochemical data in an attempt to delineate geochemical haloes related to alteration and attendant mineralisation within the Broken Hill Group rocks. According to a study conducted by Rugless and Govett (1984) on Pinnacles-type mineralisation at Broken Hill, it was concluded that BHT lode horizons are characterised by coincident positive anomalies for Zn/Ba and Fe/(Na x Ba) ratios and negative anomalies for Na/(Mn x Ca) ratios, thereby uniquely defining mineralisation in weathered surface rocks. Trials done by Minotaur at Mutooroo in 2000 utilizing these element ratios had proved very successful, but did require close spaced sampling. However, similar work at Bonython Hill, although indicating the tenor of individual anomalies, again gave no definitive insight to the development of BHT mineralisation. During September 2002 a semi detailed gravity survey of 162 stations was read over the Open Dam AEM anomaly. Rock chip sampling of amphibolite and iron-bearing psammite outcrops above the anomaly returned values up to 0.3% Cu, 4 g/t Ag and 0.4 g/t Au. During April 2003, a single angled RC hole, 03RCBH03, was drilled to TD 196 m into the Open Dam AEM anomaly. A single 4 m composite cuttings sample of a fault zone cut over the depth interval 40-44 m returned 177 ppb Au. From 166-175 m depth, the drillhole intersected massive pyrrhotite-pyrite and trace chalcopyrite within a mafic gneiss unit, which it was thought adequately explained the AEM and ground moving loop Sirotem conductive responses. Anomalous Cu and Ag and weakly anomalous Au occur with the sulphides (12 m @ 0.12% Cu, 0.5-1 ppm Ag, 31 ppb Au.) Total lead and zinc values were also determined by XRF in order to test for zinc spinel (gahnite) and lead feldspar content. A subsequent review of the geophysical and geological data indicated that the Open Dam target had been adequately drill tested, with no upside likely in the immediate vicinity. Because BHT001 had proved to be a sulphide body conductor, three similar subtle, low amplitude TEMPEST anomalies apparently originating in interpreted Broken Hill strata along strike from the Open Dam prospect were proposed by BHP for follow up ground EM surveying prior to drilling (BHT013-015, BHT017 and BHT018). Accordingly, during March 2004, three 1.6 km long lines of moving loop TEM, spaced 300 m apart, were completed to the north-east of Open Dam prospect, as a continuation of the April 2002 ground EM coverage. 100 m x 100 m loop configurations were used, which detected four narrow, steeply dipping conductors. One of these EM anomalies, BHT023, coincides with a 2 km long, 1.5 mGal amplitude residual gravity anomaly, and so became of ongoing interest to the JV. During October 2005, three more of the TEMPEST AEM anomalies, BHT009, BHT016 and BHT 019 were profiled with single lines of moving loop TEM. As well, the conductive feature seen the year before at BHT023 was further investigated with two loops of fixed loop Sirotem, plus a ground magnetic survey with a 10 m station interval. During February 2006, as approved PACE Initiative Year 3 collaborative drilling project DPY3-54 arranged between Minotaur and PIRSA, a single inclined RC hole, 06RCBH04, was drilled to TD 200 m at the Round Hill prospect, to test the BHT023 combined AEM and gravity anomaly. This drillhole penetrated a sequence of mafic and felsic gneisses. Pelites were encountered between 49 and 76 m, and from 161 m to EOH. A zone of massive sulphides was intersected between 49-51 m depth, where garnet alteration was present in the pelite schist. Minotaur interpreted that the target conductive anomaly was likely to have been caused by this sulphide intercept. Slightly anomalism values were seen in copper, cobalt and zinc, and lead was very slightly elevated, with intercepts as follows: 2 m @ 0.177% Cu and 135 ppm Co from 49-51 m; 16 m @ 3075 ppm Zn from 116-132 m; 4 m @ 80 ppm Pb and 1150 ppm Zn from 160-164 m. Also during February 2006, semi-detailed gravity surveying (195 stations read at 400 m spacing along 14 lines) was performed at Round Hill prospect, as part of a wider gravity survey also addressing four other prospects on Minotaur's adjoining tenements. After processing and interpreting of this gravity data was finished, it was recommended that additional infill gravity and moving loop TEM surveys be conducted at the prospect to improve its definition.