GreenTech Metals has kicked off its mission to lift the resource numbers at its Whundo base metals project in Western Australia’s West Pilbara region after cranking up a new 2200m reverse-circulation drilling program.
The company flagged the program a fortnight ago, about a month after revealing that an extensive review, based largely on geophysics, had confirmed significant additional resource potential at the project.
The drilling program has taken on a greater importance after GreenTech confirmed in mid-May that it had signed a memorandum of understanding (MOU) with Anax Metals, with a view to establishing a “Pilbara Base Metals Alliance”.
The MOU contemplates the treatment of GreenTech’s Whundo project ores at Anax’s Whim Creek processing plant. The duo’s plan is for the partnership to evolve into a base metals processing hub for the region – a move it sees as offering significant corporate, operational and financial benefits.
It is envisaged to become a catalyst for the West Pilbara to become a significant copper producer and an opportunity for GreenTech to develop Whundo at a time when the reddish metal’s price has been running hot – with a processing plant sitting just 100km down the road at Whim Creek.
GreenTech Metals executive director Tom Reddicliffe said: “We are excited to have started our follow-up staged drill program at Whundo, with the first drillhole being on the Austin target.”
Anax’s Whim Creek project contains an estimated resource of 11 million tonnes at a grade of 1.1 per cent copper and 1.7 per cent zinc. The current JORC-compliant indicated and inferred mineral resource for GreenTech’s Whundo and Ayshia deposits is 6.19 million tonnes at 1.12 per cent copper and 1.04 per cent zinc.
Combined feed from the two sites to the Anax plant could significantly extend the life of one or both of the projects.
GreenTech has designed the new drilling program primarily to test its underexplored – or unexplored – Austin, Shelby and Yannery targets and possible extensions of the Ayshia deposit, all of which are associated with distinctive fixed-loop electromagnetic (FLEM) geophysical anomalies.
Most of the proposed metreage constitutes step-back holes to intercept inferred down-dip projections of mineralised zones defined by previous drilling or geophysical conductors – or combinations of both.
The big Austin FLEM target straddles inferred northerly or north-westerly down-dip trends of Whundo’s east and west deposits that appear to be open to depths of about 300m below surface. Previous drilling up-dip from the Austin drill target includes a succession of solid intercepts running copper grades commonly in the range of 1 to 2 per cent copper, with occasional intercepts of up to about 3.2 per cent copper.
The Shelby target, highlighted by relatively weak EM anomalism, lies 550m north of Austin and is interpreted to be a deep, high-grade target. The target depth might be the reason for the lower intensity of the EM, but a previous hole put in by GreenTech nailed 14m at 0.5 per cent copper from 417m including 3m going 1.3 per cent copper from 428m.
Management believes that justifies the proposed single step-back vertical hole to some 500m in depth.
Only Yannery has been worked historically in a succession of shallow oxide open pits. Previous drilling has identified typical shallow supergene oxide copper mineralisation with high grades up to 23.1 per cent copper and 37.1 grams per tonne silver. GreenTech says it will initially focus on fleshing out Yannery’s potentially high-grade shallow supergene copper-silver mineralisation.
Copper-zinc mineralisation at Ayshia has been defined down-plunge by previous drilling to about 250m below surface and remains open at depth. The company is now planning two holes off the same drill pad to test for possible down-dip or down-plunge extensions of the Ayshia lode to about 300m vertical depth.
Management says it will run downhole electromagnetic (DHEM) surveys on selected holes in a bid to identify additional mineralisation and assist in the definition of future drill targets.
While it is difficult to quantify the extent of resource increases that may accrue from the program, existing drill sections point to positive down-dip or down-plunge continuity to appreciable depths and good consistency of copper grades.
That seems to put GreenTech in a position to be able to develop meaningful resource upgrades with a relatively compact, logical and economical program that will determine the future steps at Whundo.
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By Doug Bright
