Silver Mines Australia has surprised with a sharp increase in the size of its resource at its Bowdens prospect in central western NSW which now contains not only lots of silver, lead and zinc, but also gold – with more on the way.
In the second announcement this week, Silver Mines Friday said Bowdens now contained 200 million tonnes at 62 grams silver to the tonne of silver equivalent (measured that way because silver remains the dominant metal).
The breakdown is 29 grams of silver to the tonne, 0.37% zinc, 0.26% lead, 0.07% gold at a cut-off grade of 30 grams to the tonne silver equivalent, giving a total resource of 390 million ounces of silver equivalent.
“The updated Mineral Resource estimate will be used to optimise open-cut mine studies and drive Mineral Resource to Ore Reserve conversion,” the company said on Friday.
The company said the new mineral resource estimate “includes 19 million tonnes @ 0.31 grams to the tonne gold for 190,000 ounces of gold (at a 0.2g/t gold cut-off)” and that “the addition of gold to the Mineral Resource estimate adds significant value to the project.”
And the prospect of identifying more gold areas looks like being a key part of the company’s continuing exploration work and will play an important part in feasibility study updates and final investment decisions.
There also is slightly more lead and zinc in the latest estimates.
“In comparison to the 2017 Mineral Resource estimate, the updated Mineral Resource estimate is a 56% increase in tonnes, a 16% increase in silver ounces and a 44% increase in silver equivalent ounces, with an 8% decrease in silver equivalent grade.
“This decrease in silver equivalent grade is a result of significant tonnages that contain lower grade silver but include gold and increases in base metals (zinc and lead) in the deposit below the existing proposed pit design,” the company explained on Friday.
“Reported at a 30 g/t silver equivalent cut off, the Bowdens Silver Mineral Resource extends from surface and is trimmed to approximately 320 metres below surface. It is the opinion of the Company that this represents a potential target volume for future open-pit mining.
“Much of the increase in Mineral Resource is in the shallower, southern portion of the deposit and within the basement Coomber Formation below this, in addition to areas peripheral to the north and northwest of the currently proposed open-cut pit (to be updated with optimisation studies),” the company said.
Silver Mines said the Bowdens silver deposit contains significant higher-grade portions within the Mineral Resource estimate which “are 79% of (the) total mineral resource estimate tonnage.” That’s a large 158 million tonnes.
Friday’s announcement came just two days after the company revealed it had found more gold at Bowdens. The gold was found outside the established silver lead zinc area, and in parts of the existing resource area.
Silver Mines CEO Anthony McClure said in Friday’s statement:
“In what was already Australia’s largest known undeveloped silver deposit, this further increase is exceptional,” the company said on Friday.
“We will now move rapidly in our Ore Reserve assessment as part of the optimisation of the Project’s Feasibility Study in lead up to the proposed Bowdens Silver mine development.
“The high component of Measured and Indicated Mineral Resources reflects increased geological confidence and provides considerable scope in delivering further project longevity.”
In its first statement to the ASX Silver Mines said it now had two diamond core rigs drilling on site. “Exploration targets at the Bowdens Deposit currently include extensions to the Underground Mineral Resource estimate (below 200 metres) where it remains open, including the Southern Gold Zone, and regional exploration targets as defined by the 2022 seismic survey.”
“Exploration drilling during the second half of 2022 tested for extensions to mineralisation outside the current planned open-cut pit design and for higher grades within the open-cut pit design.
“Multiple areas have been targeted for extensions including in the north at Main, Aegean and Northwest Zones and in and to the south of the planned open-cut pit at the Southern Gold Zone.”
“The updated Mineral Resource estimate will serve as a foundation for updating the 2018 Feasibility Study including definition of updated Ore Reserves and the further engineering design of the Bowdens Silver Project mine site layout.
“GR Engineering Services Ltd will lead the overall Feasibility Study optimisation and Entech Pty Ltd have been engaged to conduct open-cut pit optimisation studies, considering updated geotechnical, metallurgical and economic information.
“The objective is to maximise the conversion of the Mineral Resource to Ore Reserve. The Company is confident that these efforts will yield positive results and further enhance the value of the Bowdens Silver Project,” Friday’s release said.
