Great Boulder Resources: The road to a once overlooked ‘big prize’

The first gold discovery in Meekatharra, in the Murchison region of Western Australia, was made about 130 years ago and since then there has been plenty of exploration and mining.

But despite the emergence of many major mining operations over that time, it appears some of those explorers overlooked other potential multi-million-ounce opportunities.

Andrew Paterson, Managing Director of Meekatharra-focused Great Boulder Resources (ASX:GBR), tells Mining.com.au the majority of exploration and all mining has been concentrated on the west side of the Meekatharra greenstone belt.

“Heading east there’s a plain of shallow alluvial cover which obscures underlying geology, so no doubt that would have discouraged early explorers,” he says.

“Interestingly though, the rocks hosting the initial gold discoveries run north-northeast from town before folding around and coming back down the other side of the belt about 12km east of town, like a huge inverted U-shaped fold.”

This is where Great Boulder has made some interesting discoveries at its Side Well Project that the company believes is a completely new style of mineralisation for the multi-million-ounce Meekatharra Goldfield.

Great Boulder is seeing potential for these new discoveries to shape Side Well, which so far has a resource of 668,000 ounces, into a large new gold camp.

The Mulga Bill prospect — a 6km corridor of gold and pathfinder anomalism — has previously returned very high grades of vein-hosted gold up to 3,451 grams per tonne (g/t).

Paterson says the Mulga Bill prospect is in the middle, under the alluvial cover, but the more recent discoveries are further east in exposed geology.

“Despite it seeming an obvious target now, a lot of these areas have received little or no attention,” he says.

“I would guess there are many reasons for that, including the gold price history and perhaps hubris on the part of previous explorers.”

A ‘greenfields project in a brownfields area’

Western Mining Corporation (WMC) — which was acquired by BHP (ASX:BHP) in 2005 — Dominion and Esso Exploration all previously had brief exploration programs in the area.

Interestingly, WMC hit gold at Mulga Bill around the same time it uncovered Andy Well — a high-grade deposit that eventually produced over 350,000 ounces at 8g/t for Doray Minerals between 2013 and 2017. But the Mulga Bill discovery was never followed up.

“They were looking for four-million-ounce targets, so Meekatharra didn’t fit their corporate strategy at the time,” Paterson says.

“This is why we describe Side Well as a greenfields project in a brownfields area. A lot of our targets don’t have any previous historic drilling, which is very unusual so close to an historic field.”

The eastern area, including the Ironbark prospect, is the “stratigraphic equivalent” of the rocks hosting Westgold Resources’ (ASX:WGX) multi-million-ounce Paddy’s Flat operation, Great Boulder says.

Side Well has been described as a large-scale intrusive-related gold system. Paterson says one of the main attributes of these types of systems is their size potential.

“The term intrusive-related gold system literally means there’s a big intrusion sitting somewhere in the vicinity which originally provided the heat source to drive mineralising fluids through the rock,” he explains.

“When we initially identified intrusive-related signatures over several kilometres of strike, that gave us a lot of confidence that there was a big prize to be found.”

Great Boulder is working to boost the resource to 1 million ounces, which it believes it can do by late 2025. 

The existing 668,000-ounce resource sits within the Mulga Bill and Ironbark prospects. However, Great Boulder has identified growth opportunities outside the resource area.

“Saltbush is the first new target to be tested outside those areas and we’ve already identified gold mineralisation over 300m of strike, so we’re confident that will come into the resource inventory soon,” he says.

“Beyond that we have a bunch of new targets we’re just starting to test, and then similar geochemistry continuing south in areas we’ve done no work on yet.”

Great Boulder is undertaking reverse circulation drilling at Saltbush and Mulga Bill North. After that the company will switch back to aircore drilling and restart testing of the new targets along the 14km-long Ironbark Corridor.

While those programs are in progress, Great Boulder is also planning to start heritage clearances on the tenements south of Saltbush, and undertake additional surveys at Polelle to pave the way for drilling of those areas as well.

Processing optionality

Great Boulder lodged a mining lease application over the 100,000-ounce Ironbark prospect in June 2023. The company believes there is potential for the deposit to provide early cashflow while it continues regional exploration.

The Side Well Project sits less than 25km from Westgold’s 1.6-million-tonne-per-annum Bluebird processing plant.

This provides Great Boulder with options for processing which the company plans to explore in an upcoming Scoping Study.

“We’re hoping to start scoping work early next year and we’ll consider all options, including building our own plant or possibly a combination of both, with ore delivery to Bluebird in the first couple of years to generate cashflow while we build our own plant,” Paterson says.

Great Boulder acquired an option over the Side Well Project in July 2020 from a private Kalgoorlie-based company. Prior to the announcement, the company’s shares were trading at $0.022. By September 2021 they had reached a peak of $0.204 — an 827% increase.

While they have come back a fair bit, shares are still up over 190% at $0.064 for a market capitalisation of $37.8 million.

“I know some observers may think the phrases ‘company-making’ and ‘transformational’ are overused industry hyperbole, but if you consider where Great Boulder came from prior to acquiring Side Well I think you’ll agree it’s already transformed the company,” Paterson says. 

“GBR was a micro-micro-cap with three employees and we were looking for something to take us to the next step.

Now we’re still small, but we have a highly-trained team of passionate explorers who are really good at what they do and have a great understanding of what to look for around Meekatharra. The company has grown six to eight-fold on a market cap basis and we have a lot more growth to deliver.”

At the same time, Paterson says it feels like the risk appetite of investors is returning to the gold exploration space, albeit slowly.

This no doubt has a lot to do with the price of the precious metal hitting an all-time Australian dollar record of over $3,700 an ounce in mid-April 2024. The price is currently sitting over $3,600 an ounce.

“We’re still fairly cautious but we’re also keen to accelerate progress as soon as we can,” Paterson says.

This is factoring into an increase in mergers and acquisitions in the space. Paterson says the majors and mid-tier miners are going to need to replace their reserves and for them it is often cheaper to buy ounces than find them.

However, Great Boulder is keen to bring its Side Well Project into production itself in the “not-too-distant future”.

Write to Angela East at Mining.com.au

Images: Great Boulder Resources
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Written By Angela East
Managing Editor Angela East is an experienced business journalist and editor with over 15 years spent covering the resources and construction sectors and more recently working as a communications specialist handling media relations for junior resources companies.