GreenTech Metals has hailed significant results from its first two diamond drill holes for 1187 metres at its Whundo volcanogenic copper-zinc project south of Karratha, including 7.14m at 1.46 per cent copper and 1.23 per cent zinc from 277.16m.
The intercept from the company’s unmined Austin conductor target includes 6.3m going 1.84% copper and 1.4% zinc from 278m, including 3.45m assaying 2.42% copper and 2.41% zinc from 278m.
GreenTech put a second hole into the never-mined Shelby conductor, coring out 9.94m going 1.32% copper and 0.18g/t gold from 598.2m, including 6.34m at 1.68% copper and 0.16g/t gold from 598.2m, and 2.5m running 2.21% copper, 0.16% zinc and 0.08g/t gold from 602m.
It also intercepted another 3.69m grading 1.18% copper and 0.35g/t gold from 626.3m.
Only trace gold was picked up in the Austin intercepts, between 0.08 and 0.1g/t.
GreenTech’s drill program is exploring a series of northward-plunging conductor plates, which could represent extensions to known mineralised shoots along the 2 kilometre Whundo mineralised trend, which includes the Austin, Shelby, Yannery and Ayshia zones. The company aims to identify increased resource potential at Whundo.
The program began in December and experienced delays due to cyclonic weather and some required adjustments to the Shelby drilling to keep the deep hole on track to its target.
The Shelby hole ran to a total depth of 815.7m and the Austin hole attained 371.4m. Both holes were drilled at an inclination of 67 degrees but on different azimuths.
GreenTech was rewarded with both holes intersecting massive to semi-massive sulphide comprising chalcopyrite (copper iron sulphide), sphalerite (zinc-iron sulphide), pyrrhotite (a magnetic iron sulphide) and the iron sulphide, pyrite.
The intercept depths are consistent with the interpreted down-dip extensions of previously intercepted mineralisation and also with the interpreted conductor locations.
These results continue to confirm the high copper and zinc grades found at the old Whundo copper mine, which was last mined in 2006.
The Shelby hole intersected massive, semi-massive, disseminated and blebby sulphides from 598.1m to 608.14m, representing an intercept that is close to 9.94m true width.
The Austin hole intersected massive and semi-massive sulphides from 277.17m to 284.3m, which represents close to true width of 7.14m.
GreenTech’s executive director Tom Reddicliffe said: “We are very encouraged with these results which confirm our visual confirmation of massive to semi-massive sulphides containing copper and other metals associated with the conductor targets tested at both Shelby and Austin. The results confirm that these two mineralised shoots are continuing down plunge and present a great opportunity to expand the Whundo project resources.”
GreenTech has completed down hole time domain surveys in both drill holes. Southern Geoscience consultants interpreted the results, alongside other geophysical surveys completed in 2024.
The new geophysical model at Shelby places the conductor source immediately west of the latest sulphide pierce point, extending beyond the boundaries of the 2024 surface survey. Southern Geoscience has recommended it for further testing.
Surface geophysics at Austin supports good potential for a greater plunge extent and places the centre of the conductor source about 50m west/northwest of the latest sulphide pierce point.
That target has also been recommended for testing, along with additional step-out holes to test the larger plunging conductor.
The recent drilling program at Austin and Shelby has provided useful and detailed geology that enables relative stratigraphic positioning of the mineralised horizons.
As part of an upcoming stage two drill program, the area between Austin and Shelby will be targeted for potential continuity of the copper mineralisation between the two shoots, neither of which have been previously mined.
The two mineralised shoots’ proximity, common plunge and lateral dip raises the possibility they may simply be two more conductive parts of a single mineral shoot.
GreenTech says it will also now assess its drill results for critical metals after identifying elevated gallium to 114 parts per million in several samples from both drill holes and close to the copper mineralisation.
The average abundance of gallium in the earth’s crust is relatively low, typically less than 19ppm. This curious metal does not occur as a free element in nature but is often identified in compounds, such as bauxite and sphalerite.
GreenTech’s stage two drilling program will continue to seek out a significant expansion of the existing of the 6.19 million tonnes at 1.12% copper and 1.04% zinc Whundo/Ayshia mineral resource and where possible, identify new resources.
The current buoyant copper price has led the company to consider near-term opportunities for potential copper production from Whundo.
The imminent program will focus on testing the down-plunge and lateral extents of the Austin shoot, the lateral extents of the Shelby shoot, the down-plunge extent of the Ayshia shoot and the upper high-grade oxide zone at Yannery.
It will also put in a core hole at Whundo to provide material for metallurgical test work.
GreenTech will plug the latest drill results into a conceptual Whundo mine study to assess the economics of near-term production opportunities and it will also assess the Radio Hill processing site as an option for Whundo ore treatment.
The company figures the current targets associated with known mineralised shoots could significantly increase the current copper-zinc resource.
But for now, drilling and interpretations to date point to significant expansion potential that could be realised with further drilling along strike and at depth.
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By Doug Bright
