For earlier reports on its base metal exploration that were submitted by BHP Minerals covering the three licence reporting years 4/8/1995-3/8/1998, see the separate index record for Env 09983. Exploration undertaken within a large licence area located north of Leigh Creek has been directed at evaluating occurrences of Neoproterozoic stratabound magnesite mineralisation known to exist in the region. In reporting year to 31st August 1999, the known magnesite deposits at Termination Hill, Pug Hill and Mount Playfair were examined for potential mining development, while independent investigations addressed the copper-base metal potential of the Submarine prospect located on the southern flank of Termination Hill, generate a map of magnesite distribution, which corresponded well with the previously completed detailed surface mapping of each the three deposits, and was able to be used to extrapolate information about magnesite bed thickness and lateral continuity. Deposit delineation diamond drilling was undertaken at Termination Hill, Pug Hill and Mount Playfair between October 1998 and February 1999, comprising respectively 10 inclined holes for 921.5 m (THDDH01-THDDH10), 13 inclined holes for 984.9 m (PHDDH01-PHDDH13) and 6 inclined holes for 397 m (MHDDH08, MHDDH10-MHDDH14). Drill core samples were submitted for whole rock analysis and batch leach metallurgical testing. The resulting combined resource for all deposits was estimated to be 66 Mt @ 42.8% MgO (measured, indicated and inferred), representing a total measured plus indicated resource of 23 Mt and an inferred resource of 39Mt. A measured magnesite resource of 4 Mt was outlined at Termination Hill. Known copper and base metal mineralisation at the Submarine prospect occurs in rocks forming part of the Ideyaka Diapir, which contains rafts of basic Wooltana Volcanics. Reconnaissance rock chip sampling (4) undertaken by Pima NL for petrological and geochemical investigations failed to identify any significant mineralisation, so no further work was planned for there. In the 12-month reporting period to 7th November 2001, exploration undertaken on renewed EL 2765 included trial mining of 100 tonne of magnesite from the Mount Hutton Proven Ore Reserve (held by SAMAG on EL 2565, ML 6092), for testing a selective mining method that differentiated between the steeply dipping tabular magnesite beds and the dolomite interbeds. The grade of the extracted bulk sample verified the resource model parameters and confirmed the selective mining approach. [See also a separately indexed report held in ENV 09776). Accordingly, multiple mineral claims, retention leases and mining leases were pegged and granted across EL 2765. In the 12-month reporting period to 7th November 2002, non-field-based activity was restricted to making strategic considerations about mining the Termination Hill and Pug Hill deposits. The location of the deposits and need for significant upgrading of access to enable bulk road transportation to the railhead at Leigh Creek was seen as restricting the viability of mining these two deposits, and therefore no further work on them was recommended. The Ideyaka Diapir was still regarded as prospective for buried copper-gold deposits because it remained untested. The final year of reporting (to 7th November 2003) is indexed separately in Env 10529 (CNO:2025057).