GreenTech Metals is putting the finishing touches on a new 2200m reverse-circulation (RC) drilling plan aimed at lifting the resource numbers at its Whundo volcanogenic massive sulphide (VMS) deposit in Western Australia’s West Pilbara region.
The move follows the company’s detailed review of the old Whundo and Ayshia deposits and other spatially or geologically-related targets identified between the two zones, primarily from fixed-loop electromagnetic (FLEM) geophysics.
Management says its new base metals focus will be backed by the prevailing high copper prices and its recently-forged “copper alliance” with next-door neighbour Anax Metals. That agreement has been struck with a view to establishing a new Pilbara copper processing hub at Anax’s historic Whim Creek mining and processing centre.
GreenTech’s Whundo and Ayshia deposits are currently the sole contributors to the company’s combined JORC-compliant indicated and inferred mineral resource estimate at the project, which amounts to 6.2 million tonnes at 1.2 per cent copper and 1.04 per cent zinc. 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.
And this is before any new resources are defined by GreenTech’s infill or extension work at its Whundo and Ayshia deposits, or from potential new discoveries.
Greentech Metals executive director Tom Reddicliffe said: “Having just entered into an alliance with Anax Metals to assess potential pathways to develop Whundo, there isn’t a better time than now to expand the resource base. With copper prices having increased some 30 per cent in the past 6 months and predicted to continue to rise reflecting increasing demand, GreenTech is well placed to benefit from these substantial tailwinds.”
Management says its proposed drilling will focus on its new FLEM or under-explored targets at the Austin, Shelby and Yannery prospects and also at Ayshia. Recent scout drilling at the first three prospects has already intersected significant copper mineralisation.
The majority of the proposed RC drilling 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.
Downhole electromagnetic (DHEM) surveys will also be undertaken on selected new holes to confirm up-dip and down-dip mineralisation continuity from the holes and to search laterally for any new zones nearby.
The company’s big Austin FLEM target which straddles both the Whundo East and West targets is interpreted to be a deep, high-grade conductor that appears to partly underlie both zones and looks like it could be more than two and a half times their combined size.
GreenTech is planning two step-back holes at Austin to about 300m depth below surface to test multiple strong, downdip EM conductors below the nearest recent intercept, which nailed 19m at 0.81 per cent copper and 0.15 per cent zinc from 225m.
That intercept includes 15m going 1 per cent copper from 226m including 6m running 2 per cent copper from 226m, which in turn includes 1m at 5.4 per cent copper from 226m.
When compared with the next closest intercept up-dip, the mineralised structure appears to be thickening with increasing depth. That will be tested by the proposed two holes, with the possibility of transforming the project if the down-dip thickening trend is confirmed.
GreenTech’s Shelby target is centred about 550m north-east of Austin-Whundo along the prevailing strike of the overall local trend of the VMS anomalism and is also interpreted to be a deep, high-grade target.
Management says the deep and weakly-conductive Shelby target was defined by Fox Resources in 2006. Diamond drilling by Fox produced an intercept of 11.25m at 1.6 per cent copper from 391.25m including 5.8m going 2.4 per cent copper from 391.25m.
A later down-dip scout hole by GreenTech intercepted 14m at 0.5 per cent copper from 417m, indicating the strong possibility for down-dip continuity of the mineralisation identified in the Fox drillhole, which is also reflected by two EM conductors.
GreenTech is proposing a single deep vertical step-back hole to more than 500m below surface to sort out that story. While the intercepts to date have been in the 11m to 14m range, grades are strong and any increase in thickness will build encouragement for Shelby’s potential to contribute to the resource base.
The Yannery target lies about 800m north-east of Whundo and has been worked historically to shallow depths for its oxide resources. Reconnaissance drilling last year produced a best intercept of 8m at 5.2 per cent copper from 31m, including 1m running 23.1 per cent copper and 37.1g/t silver from 34m.
It is classic oxide-style copper mineralisation, but insufficient drilling has been undertaken to date to define a resource. The proposed drilling program will initially focus on outlining the lateral and depth extents of the relatively shallow, high-grade supergene mineralisation remaining at Yannery.
At Ayshia, 1.5km north-east of Whundo, the current inferred mineral resource has been defined to 300m depth down-plunge and to about 100m width and remains open at depth. The mineralisation appears to flatten slightly and thicken with increasing depth to at least 230m vertically below surface, where a previous diamond hole intercepted one of the better copper grades, with 23.7m running 3.2 per cent copper and 0.4 per cent zinc from 209m.
A deeper step-back hole intercepted 13.97m at 3.19 per cent copper and 0.42 per cent zinc from 243.63m and appears to demonstrate thinning of the zone at this point. GreenTech is planning two near-vertical step-back holes from the same pad to about 300m vertical depth to resolve the question.
Management says it has engaged a drilling contractor for the campaign, which is slated to begin in the next few weeks once final preparations are completed.
The new alliance with Anax presents the best possible opportunity in the entire history of Whundo to properly test and potentially exploit the intriguing resource area. It may also encourage further exploration for other base metals in the region.
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By Doug Bright
