WA Leonora
Gold areas represent exploration licences.
In the Leonora region, exploration has been focused on definition of additional high-grade ore sources to completment production from Gwalia. High-grade reserves of 2.1 Mt @ 4.7 g/t for 323,000 oz have been defined recently at Tower Hill. Other areas prospective for gold and base metals have been identified and will be followed up.
Gwalia
The Gwalia deposit has more than 4 million ounces of gold in resources. From 1,040 metres to 1,730 metres below surface, Gwalia has an average resource endowment of 5,000 ounces per vertical metre, reaching a maximum of 10,000 ounces/ vertical metre at a depth of 1,500 metres below surface.
The deposit is strongly mineralized and open-ended at depth but adequate drilling density, and therefore resources, are only available to 1,730 metres below surface.
The deepest two holes in the dominant lode, the Southwest Branch, down to 1,900 metres below surface, reported true widths of 20.6 metres at 21.4g/t (hole GWDD12C) and 12 metres at 35.7g/t (hole GWDD12D). These holes demonstrate the opportunity for significant extensions of mineralisation beyond the current resource.
Leonora Gold Exploration
The recent discovery at Tower Hill lies 2 kilometres north of the Company’s Gwalia gold treatment plant. Previous open pit mining at Tower Hill ceased in 1989 and recovered approximately 176,000 ounces to a depth of 80 metres. The gold mineralisation at Tower Hill is quartz-hosted, with many similarities to Gwalia.
Tower Hill has a one kilometre strike length, dipping at 40 degrees to the east. Previous drilling showed continuity of mineralisation to vertical depths of 200 metres. Recent reverse circulation and diamond drilling has extended the mineralisation to at least 450 metres depth and achieved true width intersections of 41 metres at 5.5g/t, 40 metres at 6.0g/t, 30 metres at 7.2g/t, 50 metres at 3.7 g/t, 33 metres at 4.2g/t and 10 metres at 10.7 g/t at depths of 230-300 metres which indicates an apparent improvement in gold grades at these depths. Drilling is now underway to extend reserves below 500 metres below surface and to the south.
There remain a number of attractive potential targets for open pit mineralisation in the Leonora region, with emphasis on the granite-greenstone contacts which hosts most of the significant deposits in this belt. Exploration at Tarmoola has switched to a focus on high-grade shoot positions down-plunge from the existing pit. Broad-spaced drilling has returned high-grade intersections on the carapace above the granite including 3.7m @ 33.5 g/t from 588m and 5m @ 7.5 g/t from 556m, 7.4m @ 16.1g/t from 167m, and 7m @ 6.1 from 295m. Other projects of interest include Forrest, Poker, Trump, Kailis and Harbour Lights.
Base Metals
St Barbara's base metal exploration programmes have gained momentum over the past year. The Company's extensive tenement position allows it to target nickel sulphide mineralisation along strike from the well-endowed Leinster Nickel Operations and copper-zinc mineralisation along strike from the high-grade Teutonic Bore-Jaguar volcanic hosted metal sulphide deposits.
Results from initial reverse circulation and diamond drilling at Leonora have been encouraging. Cumulate ultramafic rocks are present, reflecting an energetic magmatic environment. A sulphidic sediment is also intermittently developed along the basal contact, providing a potential source for sulphur saturation. Intersections of disseminated to blebby sulphides have confirmed the prospectivity of the ultramafic units. At the Sullivans North Prospect, diamond drill hole SUDD0003 returned 0.35m @ 1.45% nickel and 0.13% copper from 331m depth. Further targets are being defined through surface and down-hole electromagnetic surveys, and ongoing mapping and gossan search programmes.
Electromagnetic and induced polarisation surveys have also been completed along strike from the Teutonic Bore and Jaguar copper -zinc deposits. Several anomalies have been defined for drill testing. A data review has highlighted historical intersections of copper-zinc sulphide mineralisation and associated zones of alteration at the Gravel Pit and WTB-45 Prospects, on St Barbara's tenements to the north of Teutonic Bore. Initial drilling has returned several mineralised intersections, including 0.3m @ 5.6% Cu, 0.4% Zn and 221 g/t Ag from 243m.
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