Tasmania Projects - Gold
Mt Charter Gold-Silver project (100% BSM)
The initial Mt Charter resource of 378,000 ounces gold-equivalent provides for a significant platform from which to continue to grow and develop a Tasmanian gold business. The Company has a pipeline of projects to achieve this.
BSM recognised the gold potential of the Mt Charter area and soon after the Company was listed on the ASX initiated a drilling programme to enable a mineral resource estimate for the Mt Charter Au, Ag, Ba and Zn deposit. The deposit is located approximately 4km south west of the Hellyer deposit and 2km west of the Que River deposit in a similar VHMS style geological setting. A schematic drill hole location plan and simplified geology is provided in Figure 11 and two representative drill sections in Figures 12 & 13.
Table 5: Summary of Classified Mt Charter Mineral Resource (0.7g/t Au cut-off)
The total combined Mineral Resource estimated for the Mt Charter deposit is 6.1 million tonnes at 1.22 g/t Au, 35.5 g/t Ag, 9.7 % Ba and 0.5% Zn. The resource is reported above a 0.7 g/t Au cut-off within the mineralised envelope boundary and is classified as Indicated and Inferred Resources according to the JORC code (December 2004), as listed in Table 5.
The tonnage and grade estimation is based on a ‘change of support’ geostatistical technique that is targeted at modelling the deposit behaviour using anticipated open pit mining on five metre high benches and a mining selectivity of 5 metres by 10 metres by 5 metres. The change of support process is based on multi-element conditional simulation. Full details on the estimation process are provided in a report to the ASX dated 30 October 2006.
The Mt Charter mineralisation interpretation for this estimate was compiled by Dr Travis Murphy; BSM’s Exploration Manager – Eastern Australia, with assistance from Snowden Mining Industry Consultants. Paul Blackney of Snowden reviewed data collection procedures undertook database checks and inspected core on site. Shaun Hackett (Snowden) reviewed the geological interpretation and was responsible for compiling the grade estimates. Both P Blackney and S Hackett are Competent Persons being Members of the AusIMM with more than five years experience relevant to gold and multi-element mineral resource estimation.
Figure 11: Drill hole location plan and simplified geology
Figure 12: Schematic drill section-4640mN
Figure 13: Schematic drill section-4690mN
Metallurgical Testwork
Metallurgical testwork has been undertaken to gain a preliminary understanding of the metallurgical characteristics of the Mt Charter mineralisation and its response to possible processing routes. Testwork included head assay, mineralogy, direct cyanidation and sulphide flotation followed by cyanidation then barite recovery by gravity and barite flotation.
A composite sample representing variable depths, gold, silver, zinc and copper contents was submitted for testwork. The Bond ball mill work index was determined to be 14.7kW/tonne. Summary results for cyanidation and flotation testwork are presented in Table 6 below.
Table 6: Summary of Metallurgical Testwork Results
The objective of the flotation testwork was to assess the flotation behaviour of Au, Cu, Ag Pb and Zn mineral species and to float a bulk sulphide concentrate. These preliminary, bench scale test results show encouraging recoveries using a flotation stage followed by a cyanidation process route. The low recovery of precious metals by direct cyanidation is consistent with historic results reported previously and appears to be attributable to approximately 50% of the gold being present within the sulphide mineral grains. Direct cyanide recovery was relatively insensitive to grind size over a 45 to 75 micron size range.
Metals recovery to a bulk flotation concentrate is summarised in Table 7. Overall the recoveries obtained were good considering the simplicity of the flotation circuit. The objective of the next phase of testwork is to determine the upgrade potential of these concentrate grades to commercial levels. A separate test was undertaken for barite to assess flotation as a possible process for upgrading barite into a potentially saleable product. The barite concentrate produced had a barium grade of 50.2 % which is equivalent to 85.3% barite which, at first pass, exceeds the 65% barite standard generally adopted in the drilling and chemical industries.
Table 7: Flotation recovery and grade
Sterling Valley Gold Project (100% BSM)
Sterling Valley is 5km north of the 1 million ounce Henty Gold Mine (owned by Barrick), covers the prospective Henty Fault zone and includes several significant historic drill intercepts highlighting the prospectivity.
The Sterling Valley project is encompassed within the Farrell tenement boundary and is associated with the prospective Henty fault zone. The plus 1 million ounce Henty gold deposit lies approximately 5km south along the Henty Fault which also transects this licence and appears related to mineralisation already identified at Sterling Valley.
The Sterling Valley Trend extends for approximately 4km along the Henty Fault. It includes the historic Sterling Gold mine (no production records) and several drill-indicated zones of gold-arsenic-copper mineralisation. Better historic drill intercepts include:
* 7.7 metres at 3.8 g/t Au
* 3.7 metres at 5.9 g/t Au
* 17 metres at 1.5 g/t Au
Lynchford (75% BSM, 25% Clancy Exploration Ltd)
This exploration licence encompasses several historic gold mines and prospects including the Princess, Lynchford and King River Mines. Although relatively minor, three significant workings within or adjacent to this tenement include:
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Woodhill, which reportely produced some 4.6 kg of gold at a grade of 17.6g/t Au;
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Davie Workings,comprising several shafts and adits; however production records no longer exist. More recent sampling has returned high grade gold mineralisation; and
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Coupon Workings, consisting of extensive workings developed over gold bearing limonite zones. Production records are incomplete, but in 1913 some 32 tonnes of ore was recovered at a reported grade of 12g/t Au.
Several conceptual Hellyer-Rosebery style base-metal sulphide targets have also been established in this tenement.
