The abstract for this Envelope is contained (in 3 parts) as separately indexed records, due to SAMREF database system individual record data size limits presently applicable. Exploration for possible buried epithermal/hydrothermal gold deposits associated with dilational shear structures, inferred to be present within concealed Archaean basement in an area located approximately 140 km south-west of Coober Pedy, commenced with consultant Kevin Wills' interpretation of newly available SAEI aeromagnetic data to identify prospective magnetic anomalies suitable for evaluation by surface geochemical sampling and exploratory RAB drilling traverses. After this latter work had been put in train by licence operator Dominion Mining, gold anomalous prospects were quickly identified, and during May 1995 potentially economic gold mineralisation was found at the Challenger prospect within quartz-feldspar-biotite-garnet gneiss of the Christie Gneiss. Locally this host unit also contains banded iron formations plus a range of intrusive igneous rocks, mostly Archaean and Proterozoic granitoids, with lesser Proterozoic mafic dykes including some lamprophyres as encountered by drilling at Challenger. The initial regional scale sampling of pedogenic calcrete on a nominal 1.6 km staggered spacing across the licence (763 samples) was followed up by infill sampling (885 samples) conducted over nine anomalous prospects, usually at 200 m x 200 m staggered spacing, and this returned a best assay value of 180 ppb Au from the Challenger prospect. There, closer infill calcrete sampling at 100 m centres was then carried out, which defined a north-east trending anomaly with gold values > 5 ppb Au covering an area in excess of 3 km x 4 km; within this a coherent zone 1200 m x 800 m having > 25 ppb Au was recognised (peak response 296 ppb Au). In addition, infill calcrete sampling performed at the Geisha prospect, located about 37 km south-southwest of Challenger, disclosed a significant > 10 ppb Au anomaly covering an area of 1 km x 300 m, with a peak response of 24 ppb Au. It was decided to drill two RAB traverse lines spaced 800 m apart across the interpreted NE-trending Challenger calcrete gold anomaly, both lines passing outward from its peak onto the less anomalous flanks. The drillholes were inclined at 60 degrees to the east, and were continued to blade refusal or 40 m depth. Two of the holes, 95CHAR006 and 95CHAR007, made significant gold mineralised intercepts (12 m @ 4.4 g/t and 28 m @ 5.9 g/t respectively). Shortly after the first significant drillhole intercepts were obtained at Challenger, surface regolith samples were collected over the mineralisation at 50 m spacing to compare calcrete, soil and lag geochemical assay results. Samples were collected along a 1 km east-west line and on three 400 m spaced north-south lines. The calcrete samples were collected from shallow pits, the soil samples were collected from just below surface (to avoid dust contamination from drilling) and sieved to minus 80 mesh size, and the lag samples were collected from surface with the -5mm to +2mm size fraction retained. The assay results showed that all three sampling methods are easily capable of detecting the Challenger mineralisation, but there are differences: - the anomaly would be most easily detected in a regional programme using calcrete: all of the calcrete samples contained above-background gold content, although the peak value obtained (620 ppb Au) was lower than that for soil or lag samples. - a low order calcrete arsenic anomaly (> 10 ppm As) anomaly is also present. - gold results for the lag samples are very high immediately above the mineralised zone (which is probably nearly in outcrop). The peak lag gold concentration is 2.7 ppm Au. This sample also contains 14.6% Ca (37% CaCO3), so at least some of the gold is probably held in calcrete, but most of it is expected to be held in ferruginous components (a logical extension of this exercise would be to evaluate gold contents in the various lag components). - within a few hundred metres distance (200-400 m) away from the mineralised zone, the lag gold values fall to background levels. - lag arsenic values define a strong (> 100 ppm As) anomaly above the mineralisation. - soil samples also define the mineralised zone (at > 50 ppb Au), but their gold values fall to background levels within 200 m distance away. - bismuth in calcrete peaks at 2 ppm Bi, with a detection limit of 1 ppm. Analytically this is probably not significant, but given the primary Au/As/Bi association, the fact that "detectable", i.e. >1 ppm bismuth values coincide with the best gold values, suggests that at lower detection levels bismuth may be useful. It was concluded by Dominion that the Challenger bedrock gold mineralisation could have been found using soil or lag sampling instead of just calcrete sampling, but that a far higher sample density would be required if these geochemical exploration techniques were to be applied regionally. As the Challenger mineralisation has only thin surficial cover, which is not typical of the region, calcrete remains the preferred sample medium. All of the early drilling conducted on the Jumbuck licence was targeted solely on calcrete geochemical anomalies. Drill targets were selected based on criteria of size, order of anomaly and cohesiveness: the aeromagnetic response or inferred lithology played little part. This was particularly the case with the Challenger anomaly, where the magnetics are quiet and the inferred basement lithology was thought to be felsic gneiss. Prior to commencing evaluation bedrock RAB drilling of the significant calcrete gold geochemical anomalies, Dominion decided to drill several vertícal RAB/OHP holes at both the Challenger and Geisha anomalies. The purpose of these holes was to determine the thickness and type of regolith, the extent of development of a pallid zone and/or saprolitic weathering, and the depth to and type of recognisable bedrock. With this data to hand it was believed that comprehensive drill testing of an anomaly would be more effective. Three holes, 95CHAR001 - 95CHAR003, with a total penetration of 127 m, were drilled at Challenger, plus one 60 m deep hole at Geisha. All three holes put down at Challenger intersected a shallow (up to 5 m thick) regolith layer consisting of aeolian sand, calcrete, silcrete and indurated pallid clays. This was underlain by a poorly developed saprolitic, kaolinitic to limonitic pallid zone. Underlying the pallid zone, a strongly to slightly weathered quartz-feldspar-biotite-garnet gneiss was penetrated, within which all the holes were terminated. Six-metre composite drill cuttings samples of approximately 2 kg in weight were collected using a sample spear on 1-metre ground dumped cuttings sample piles, for all three holes drilled. The single hole drilled at Geisha (95GSAR001) encountered bedrock consisting of quartz-veined feldspar gneiss, having a gold assay peak result of 22 ppb Au. The downhole geochemical sampling methodology was the same as that utilised at Challenger. Bedrock drilling at the Challenger prospect was given top priority after the revelation of its strong gold geochemical signature at the surface. During the period June to August 1995 a total of 211 RAB, RC and diamond core drillholes were completed there for a total penetration of 8251 m. From these holes it appeared that the gold mineralisation occurs as a north-dipping zone of quartz veining and silica flooding with associated chlorite and sericite alteration. A gold-arsenic-bismuth asssociation was recognised, while the mineralisation also contains visible pyrite and pyrrhotite. Initial structural interpretations for the mineralised zone favoured a north-east plunging "higher grade" gold pod, with sectional dimensions of about 80 m x 18-20 m, and a downplunge extent of at least 100-150 m. The mineralisation is located on a west-northwest trending magnetic feature, probably reflecting a fault and associated mafic dyke, which cross-cuts the regional north-east aeromagnetic grain, believed to be sourced from bedding in the Christie Gneiss. As the mineralisation appears to plunge north-east, it may well be focussed within a dilatant zone at the intersection of these two structural trends. During the second licence year, Dominion completed further appraisal drilling at Challenger, with the aim of defining an economic gold resource and bringing the deposit to the mine development stage as soon as possible. 423 RAB holes were drilled for a total penetration of 15,020.2 m, targeting the > 10 ppb Au calcrete anomaly on a 200 m x 100 m drillhole spacing that was reduced to 100 m x 50 m over identified lodes. These holes were followed by the drilling of 49 RC holes for 5625.6 m, plus one diamond tailed RC hole (HQ cored interval 107.6-166 m in hole 95CHDH585). In addition, another 86 vertical RAB holes for 3727 m were variously drilled elsewhere at the Geisha, Jumbuck and Monsoon prospects, following the conduct there of infill calcrete sampling on 800 m x 400 m grids closing in to 200 m x 200 m coverage. This initial drilling upgraded the bedrock gold potential of all three prospects after significant supergene gold (with a peak downhole value of 0.31 ppm Au at Geisha) was encountered in deeply weathered, sheared to strongly foliated felsic to intermediate gneisses. A Mobile Metal Ion (MMI) surface geochemical orientation survey was undertaken at Challenger late in 1995 (224 samples collected at 200 m x 50 m spacing) in an attempt to guide the subsequent deeper RC drilling. However, the survey results proved disappointing, as they did not pick up the known trend of the mineralisation, nor did they detect any new gold-rich zones in the near vicinity of the principal calcrete gold anomaly. Later test RC drilling of apparent MMI anomalies failed to find any gold under them down to 120 m depth. 144 line km of ground magnetic readings, and 200 ground gravity stations, were acquired during October 1995 on a 3 km x 1.8 km grid laid out across the Challenger deposit. The intent for conducting these surveys was to try to delineate gold mineralised magnetite-rich zones and the structures controlling their disposition, plus any other types of mineralisation, e.g. sulphides, that might be associated with zones of deep weathering which are detectable by gravity. The ground magnetic data was found to be very noisy, largely due to the presence of surficial maghemite. Even after performing filtering, the hoped-for subtle trends in the magnetic data still proved difficult to discern. Some strong linear magnetic responses were evident in 40 m upwardly-continued data, which are thought to be caused by mafic intrusive rocks. There are two definite trends to these intrusions, true WNW and NE - possibly reflecting a conjugate fault set. The intrusions are probably structurally controlled, since they cross-cut the regional NE-trending magnetic grain that probably reflects the pre-metamorphic stratigraphy. A number of other structures, oblique to the structures hosting intrusions, were interpreted as trending true NW-SE and true N-S. They have likely formed very late, since they cross-cut the mafic dykes, and so they are unlikely to have influenced the original emplacement of mineralisation (but could offset it today). The gravity data show a range of nearly 2 mGal within a 1.5 km x 1 km area, a considerable variation. There is a strong gradient from grid east to west, and this gradient is notably steepest through the Challenger ore zone, where it trends grid NNE (true N-S).