With world copper prices remaining close to all-time highs, GreenTech Metals believes it now has a “significant exploration opportunity” after an exhaustive review at its Whundo project in Western Australia’s Pilbara region.
The review of geophysics and drilling highlighted four significant volcanogenic massive sulphide (VMS) copper-zinc targets within a 2.2km-long zone and reveals considerable scope for resource extensions to the north-east of the 5.3 million-tonne Whundo copper-zinc deposit. The copper price hit a record $US11,060 (AU$16,816) per tonne in March 2022 and was this week still more than US$10,000 (AU$15,204) a tonne.
The project lies within a 100km radius of other potential base metals (nickel-copper-zinc) resources, including Anax Metals’ Whim Creek operation. Interestingly, Anax has this week recorded more than an 85 per cent share price hike after recently confirming it was joining with Perth-based clean metals producer Develop Global to kick off a scoping study to evaluate the treatment of high-grade ores from Whim Creek.
Whundo, which sits 30km south of Karratha, is also just 10km south of the historic Radio Hill nickel-copper resource where there is a processing hub currently on care and maintenance. The 9-square-kilometre project's 2012 JORC-compliant indicated and inferred mineral resource shows 6.2 million tonnes at 1.2 per cent copper and 1.04 per cent zinc in two deposits, Whundo and Ayshia, which are separated by about 1.5km.
GreenTech Metals executive director Tom Reddicliffe said: “We have, along with independent consultants, reviewed our current copper/zinc resources and recognised the significant exploration opportunity that Whundo presents in the resurgent copper market. We believe there is considerable scope particularly at Austin, Shelby, Yannery and Ayshia to identify additional resource tonnes to enable a step change in the resource scale.”
Reddicliffe said the VMS prospects appeared to be underexplored at depth, with very little drilling below 150m depth.
The Whundo resource comprises an indicated 4.4 million tonnes at 1.03 per cent copper and 0.89 per cent zinc, containing 45,000 tonnes of copper and 39,000 tonnes of zinc. There is also an additional inferred resource of 900,000 tonnes at 1.4 per cent copper and 0.5 per cent zinc, for a further 12,000 tonnes of copper and 4,000 tonnes of zinc.
The separate Ayshia deposit adds a further inferred resource to the current project total, with its 900,000 tonnes at 1.3 per cent copper and 2.3 per cent zinc, for 12,000 tonnes of copper and 21,000 tonnes of zinc.
GreenTech’s recent fixed-loop electromagnetic (FLEM) geophysical surveying has recorded significant EM anomalism centred on Whundo and is most intense at the adjacent Whundo West. The anomalism extends strongly to the north and north-west to centre on the new “Austin” anomaly, which is the biggest EM feature defined by the survey.
A conductor plate modelled at Austin sits on the north-west flanks of the current Whundo resource. Interestingly, the target appears to be a distinct zone that sits about 30m deeper below the Whundo East anomalism and is about 2.5 to three times the size of both Whundo and Whundo West combined.
Management believes Austin may represent a separate big body at depth beneath Whundo and that it could add considerably to its resources.
From Austin, the EM anomalism then extends further to the north-east for about 700m and is expressed as two additional zones, “Shelby” and “Yannery”. The geophysical signatures highlight an important trend of EM anomalism along the pronounced north-easterly-striking zone from Whundo towards the separate and smaller EM anomaly associated with the Ayshia deposit.
Reverse-circulation (RC) drilling at Austin jagged 10m going 2.85 per cent copper and 0.96 per cent zinc from 162m and another similar significant hit in a separate hole.
Diamond drilling by a previous explorer at Shelby – 350m north of Austin and the second biggest anomaly detected in the survey – confirmed the conductive response was associated with chalcopyrite and pyrrhotite. Another deep conductor plate has been modelled at the Shelby anomaly.
The Shelby hole intercepted 11.25m going 1.6 per cent copper from 391.25m, including 5.8m at 2.4 per cent copper, 0.6 per cent zinc and 7.6 grams per tonne silver from 391.25m, showing that the anomalism is not confined to surface zones and has some decent legs at depth.
At Yannery, 800m north-east of Whundo, one RC hole hit 21m at 2.1 per cent copper from 21m depth with multiple hits including 3m going 13.1 per cent copper from 32m and 1m at 23.1 per cent copper and 37.1g/t silver from 34m.
Ayshia diamond drilling also revealed 23.7m at 3.2 per cent copper, 0.4 per cent zinc and 0.14g/t gold from 209m, with a second hole picking up 35.7m going 1.66 per cent copper, 0.76 per cent zinc and 0.12g/t gold from 206.5m – again indicating some decent depth potential.
Mineralisation at Ayshia exhibits strong depth persistence and good thicknesses most of the way from its surface gossanous outcrop to about 260m vertical depth and remains open at depth.
In addition to the outlying new targets at Austin, Shelby and Yannery, drilling at Whundo has also picked up results GreenTech describes as “exceptional”, including one RC hole intercepting 32m running 2.43 per cent copper from 75m with 17m at 4.37 copper and 0.46 per cent zinc from 90m and 7m going 7.83 per cent copper, 0.64 per cent zinc and 0.26g/t gold from 95m.
The frequent gold credits in some of the holes are of interest, particularly with today’s Australian gold price stretching past $3530 an ounce.
VMS deposits often occur in clusters and GreenTech’s Whundo project seems typical in that respect. It appears to contain at least six significant VMS prospects identified within a 1500m strike confirmed by geophysics and drilling.
Management has identified and prioritised four new targets. It is making no secret that it is keen to explore the expansion potential of the project in view of its significant copper grades and the recent run of copper prices that now sits at about $14,800 per tonne, with the additional possibility of gold credits.
GreenTech is now planning further exploration, which it says is likely to include a combination of drilling and downhole EM geophysical surveying.
While the company has a sturdy iron in the Pilbara lithium fire through its Ruth Well project and the Osborne operation it shares with Artemis Resources, the rising copper price and global expert expectations for more to come, might just make Whundo a timely twist to the company’s pursuits.
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By Doug Bright
