Two discoveries made at opposite ends of the country and announced only months apart are dramatically changing the copper-gold exploration sector in Australia. Rio Tinto’s (ASX: RIO) massive Winu copper and gold find in the arid desert of the Paterson Province of the Pilbara Region of Western Australia (WA), and Alkane Resources’ (ASX: ALK) Boda copper-gold find in the rolling green hills of central New South Wales (NSW), are thousands of kilometres apart and in vastly different settings, but they are both considered game changers in their own ways.
One of the biggest rumours circling the Australian mining sector in the late 2000s was that global mining giant Rio Tinto had made a world class copper discovery in WA’s north-west.
While the huge potential at Winu was identified as far back as 2017, it wasn’t until February 2019 that Rio Tinto unveiled the exciting discovery to the marketplace. It was a far different story for Australian junior Alkane Resources, which couldn’t wait to spread the news that it drilled the initial Boda discovery holes in September 2019.
There are also vast differences in the exploration background of the two locations. The hot, dry, and remote Paterson Province was virtually ignored by explorers until the 1970s. Meanwhile, exploration in the Lachlan Fold Belt in NSW, where Boda is located, can trace its history back to initial gold rush days of the mid-1800s that helped kick-start Australia’s economy. However, there is one similarity between the two finds, both discoveries leading to a significant copper and gold exploration boom in their neighbourhoods.
Located approximately 130km north of the Telfer mine and 350km southeast of Port Hedland, the Winu discovery was made by Rio Tinto Exploration (RTX), which was conducting a programme specifically targeted at finding copper mineralization in the Paterson Province. The exploration programme consisted of eight reverse circulation (RC) and 20 diamond holes drilled on exploration licence E45/4833 between December 2017 and the end of 2018, totalling 13,286m (1,473 m RC and 11,813 m diamond).
Diamond drilling recommenced in mid-January 2019, with four holes completed for 1,409m. A year later Rio Tinto disclosed maiden Inferred Mineral Resource and revealed the discovery of a new zone of gold dominant mineralization approximately two kilometres east of the Winu deposit.
The Inferred Mineral Resource, reported at a 0.2% copper equivalent cut-off, was 503Mt at 0.45% copper equivalent (CuEq). This included a higher-grade component of 188Mt at 0.68% CuEq at a cut-off grade of 0.45% CuEq.
Initial studies study work suggested the copper mineralization would support the development of a relatively shallow open-pit mine. The deposit remained open at depth as well as to the north and southeast.
“We’re taking a more agile and innovative approach at Winu, and are working on the studies for a small-scale, start-up operation focused on Winu’s higher-grade core as we take another step towards commercializing this deposit. We are also assessing options for future expansion in the Paterson region given the extent of mineralization identified to date and our large land package,” Rio Tinto group executive of Growth & Innovation and Health, Safety & Environment (HSE), Stephen McIntosh, said.
“The additional exploration results reported today support our view that there is potential to develop the Paterson region into a large-scale operation over time through both our 100%-owned tenements and joint ventures. We’ve so far carried out exploration activity in just 2% of our tenements in the region and we’re building on this discovery at Winu with further encouraging results.”
In 2020, Rio continued target generation and target testing work in the Paterson Province, with 23,850m of drilling completed across 17 targets. The company is targeting first ore in 2024, subject to regulatory approvals, Traditional Owner and other consents and COVID-19 restrictions. Even before Rio Tinto confirmed the rumours about a major copper discovery in the Pilbara, explorers, big and small, started a mini “rush” to the region looking to take advantage of the “nearology” story to snap up any available land. The size of the Winu find and its effect on the Paterson Province exploration scene has seen Rio Tinto become nominated for MNN’s 2021 Explorer of the Year award.
You know you have made a major discovery when your neighbours, near and far, focus their capital raising marketing on your success, leading to Alkane Resources already earning a number of awards and award nominations for its Boda success.
Since the Boda discovery hole in September 2019, a flood of new players has entered into central NSW – with many highlighting their nearology to Boda and heading their exchange announcements and capital raising marketing on their search for “Boda style” targets.
For Alkane, the find was a real game-changer with its share price jumping from under A$0.25 to around A$1.50 a year later as the strength of that discovery was realized.
Since then a wave of new players have been “rushing” to the area picking up ground others had ignored or turned over with many considering the Lachlan Fold Belt as a mature province with all the big discoveries already made.
All that changed in September 2019 when Alkane announced the results of diamond core drill hole (KSDD003) at the Boda Prospect within its Northern Molong Porphyry Project.
That diamond core drill hole was testing a zone 200m beneath a zone of gold mineralization previously defined in RC drilling (311m @ 0.28g/t Au from 19m to EOH in KSRC018).
Assay results from hole KSDD003 indicated an increase in thickness and grade of porphyry gold-copper mineralization at depth. Drill intercept highlights included: 502m @ 0.48g/t gold, 0.20% copper from 211m; including 313m @ 0.62g/t gold, 0.17% copper from 228m including 12m @ 3.28g/t gold, 0.67% copper from 419m and 35.8m @ 0.21g/t gold, 0.49% copper from 735m to EOH.
The drill programme at Boda continues and results received in May 2021 demonstrate further continuity of the high-grade breccia at Boda, as well as showing extensions to the mineralized system to the south at the Boda Two target.
One diamond core hole, KSDD031, successfully intersected the sulphide cemented breccia down dip with significant assay results of: 383.2m grading 0.80g/t Au, 0.31% Cu from 775m, including 204m grading 1.40g/t Au, 0.51% Cu from 776m, 101m grading 2.47g/t Au, 0.83% Cu from 824m, and 70m grading 3.04g/t Au, 0.92% Cu from 829m.
“These latest results give further insight into both the high-grade brecciated zone and the sheer size of the Boda complex and adjacent complexes within the Northern Molong Porphyry Project,” Managing Director, Nic Earner, said.
“Our drilling programme continues with the aim of both in-filling and expanding the mineralized system. We expect that the ongoing drilling programme will validate the company’s growing confidence in the scale of the high-grade zone at Boda.”
With two major new copper-gold finds still being assessed and continuing to grow, copper and gold exploration in Australia is now at a fever pitch.