Exploration for graphite primarily, and secondarily for BIF-associated massive base metal sulphides, in the area surrounding the historic Uley graphite mine situated 15 km west south-west of Port Lincoln, initially comprised an airborne reconnaissance INPUT EM/magnetic/radiometric survey, with later ground EM, magnetic, SP and IP surveys to follow-up the INPUT conductivity responses. 6941 line km of aerial profiles were flown by Geoterrex in November 1980 on a 500 m line spacing, with 120 m mean terrain clearance.Numerous low EM conductivity prospective zones were defined. Upon field inspection, several exposed graphitic schist horizons were identified and channel sampled, returning values of 9.1-15.5% carbon (as graphite plus elemental carbon) when analysed. Four costeans, three dug over 480 m of strike length in the vicinity of the Uley mine, and another dug for 315 m at an undeveloped graphite occurrence located 8 km to the south-west near Sleaford Bay, all returned encouraging results from exposed graphitic layers. Ten diamond drillholes totalling 876.5 m were completed over a 3.5 square km area within 1-2 km of the mine site, with HQ cores from four holes exhibiting significant mineralised intersections, ranging up to 21.9 m at 14.3% graphitic carbon in hole 81MKD1 and 34.1 m at 12.2% carbon in hole 82MKD4. Cores cut in the other six diamond holes showed only modest graphite mineralisation, as thinner bands with lower grades. All of the drillholes were geophysically logged, but subsurface correlation of the graphite horizons proved difficult. In further-afield parts of the licence where the airborne EM data had highlighted similar EM anomalies, additional detailed ground IP/resistivity surveys were run utilising 25 m spaced dipole-dipole spreads. These defined six conductive zones, and another five diamond drillholes totalling 364.3 m were completed to test them. Graphite mineralisation was encountered in each case, giving best intersections of 8.1 m @ 8.9% graphitic carbon at the Uley Extension prospect, and 8.5 m @ 8.3% graphitic carbon at Kacey prospect. The drilling results were found to correlate well with the magnitude of the near-surface IP response, and the licensee therefore concluded that IP seemed to be an effective geophysical prospecting tool for graphite in the local geological setting. In late 1983 CRA re-evaluated its airborne EM and magnetic data with a view to assessing the licence's base metal prospectivity, and ground magnetic/SP/IP surveys totalling 15.6 line km defined ten bedrock geophysical targets, six of which were drilled (11 RC holes, total 677 m) and logged for downhole resistivity. This drilling showed the anomalies to be due to graphite, minor disseminated pyrite, or groundwater in Tertiary channels [Note: part of the data on this stage of exploration has been previously released in Envelope 6934]. Although no significant uranium, base metals or precious metals were detected, high grade graphitic intersections comparable to the Uley occurrence were made in three of the RC drillholes at Homestead, Salt Lake and Fishery prospects, indicating the strong likelihood of being able to define additional graphite reserves in the future. A geochemical association of elevated Mo with the graphite was noted. Three samples of white clay recovered from the upper section of hole 83MKRC1 were tested by Amdel, but the kaolin was found to have brightness values that are too low for paper-coating use. During 1983 metallurgical testing of core and costean samples was initiated, and preliminary feasibility studies on the mining, metallurgical and economic aspects of the Uley prospect were commenced. Split drill core samples were sent to the CRA Research Laboratory at Cockle Creek, NSW for mineralogical evaluation (correlating possible mined ore grades and mineralogy with graphite product recovery and the proportions of coarse and fine flake crystals). Beneficiation studies were commenced by the Zinc Corporation in Broken Hill on a 191 t near-surface bulk sample taken in November 1983, for which grab sampling had averaged 8.72% graphitic carbon. Eventually the Zinc Corp. were successful in separating a graphite flake concentrate with a grade of 90%+ fixed carbon, after overcoming problems of clay impurities causing some drop-out in the flotation circuit, and having also developed specific leaching methods for removal of silica and iron, the main chemical contaminants. A mine planning feasibility study, completed by CRA in June 1984 for the existing Uley mine prospect only, included the creation of plant process flowsheet data, estimates of metallurgical recovery, estimates of potential concentrate grades and sizing, plus estimates of capital costs, operating costs and possible sales revenue. The US Bureau of Mines was contacted regarding marketing strategies, and samples of the coarse flake graphite concentrates obtained by the Zinc Corp. at its pilot plant were sent to potential domestic and overseas users for them to evaluate. Comalco in Victoria was interested in using the graphite as a cathode additive in aluminium refining, but the principally sought customers were Kloeckner-Magnesital in Bonne, West Germany and Mutsubishi Corp. in Japan, as major manufacturers of carbon refractory bricks for foundry and smelter applications. These companies conducted furnace trials and favourably reported the results back to CRA. 22 Retention Leases (RLs 2152-2173) were granted on 2/10/1987 over six prospects regarded as having 'ore grade' graphite concentrations - Uley, Uley Extended, Homestead, Salt Lake, Kacey and Fishery prospects. At the cessation of exploration by CRA, the company estimated a probable ore reserve for the Mikkira deposit of 3.2 Mt @ 6% fixed carbon, with an additional 3 Mt of possible ore, which would confer a 20 year mine life if developed to yield at a rate of 300,000 tonnes per annum (tpa) of milled ore. Approximately 10,000 tpa of coarse flake and 6,000 tpa of fine flake graphite, both having 90% fixed carbon, would be the marketable products.