Great Boulder Resources (ASX:GBR) expands Ironbark gold strike and progresses development at Side Well

Great Boulder Resources (ASX:GBR) is continuing to advance its flagship Side Well Gold Project near Meekatharra, with recent RC drilling at the Ironbark deposit returning high-grade intercepts that extend the mineralised strike by 180 metres to the south of the existing 100,000-ounce resource.

The company is also progressing mine development workstreams in parallel with regional exploration, positioning itself for a potential transition from explorer to developer.

In this Q&A, Managing Director Andrew Paterson responds to key investor questions arising from the company’s 6 August 2025 ASX announcement.

How much has the Ironbark deposit grown with this latest round of drilling?

The latest round of RC drilling has successfully extended mineralisation at Ironbark by at least 180 metres beyond the current resource model, taking the known strike length to over 750 metres.

This expansion includes consistently high-grade results such as 6 metres at 8.53 grams per tonne gold from 111 metres, including 1 metre at 24.90 grams, and 5 metres at 8.91 grams per tonne from 57 metres, including 1 metre at 39.50 grams.

These results, which follow on from intercepts announced in May and June, indicate strong geological continuity and confirm the southern extension is both high-grade and open in multiple directions.

“We have now extended the Ironbark deposit by at least 180m and added significantly to the high-grade gold endowment.”

The drilling demonstrates that this southern lode is growing in scale and quality, supporting the potential for a larger gold system than originally defined.

Does this southern extension have implications for the recently completed Ironbark Scoping Study?

Yes, the high-grade southern extension sits outside the current 100,000-ounce resource that underpinned the Ironbark Scoping Study released in July 2025.

That study outlined a robust and profitable open pit operation based on existing resource figures.

These latest drilling results have the potential to significantly enhance the project’s economics once incorporated into an updated resource model, which is planned once the extent of mineralisation is fully defined.

“The recently announced Scoping Study for Ironbark highlighted the potential for a highly profitable open pit mining operation, with these high-grade additions defined by our latest drilling indicating a much larger potential resource and reserve than first considered.”

Work on mine design, approvals, and site layout is continuing in parallel, so the new data can feed directly into an updated project scenario.

What is the significance of the high-grade gold hit in the water monitoring bore?

One of the most interesting outcomes from the current program came from a water monitoring bore, 25IBMB003, which was drilled as part of the hydrogeological study required for mining approvals.

Although not designed for exploration, the hole intersected 5 metres at 14.61 grams per tonne gold from 95 metres, including 3 metres at 23.17 grams per tonne, on the southern edge of the resource model.

“This intersection, with a true width of approximately 2.5m, is significantly higher grade than the surrounding drill holes and provides additional potential for down-dip extensions.”

The result is particularly encouraging as it suggests high-grade mineralisation may continue at depth in an area that has not yet been systematically tested.

This hole has now become an important datapoint as the company plans further RC drilling to follow up the potential for deeper extensions.

How is drilling progressing at other parts of the Side Well project?

Beyond Ironbark, Great Boulder is continuing its systematic exploration across the broader Side Well project.

At Side Well South, 51 aircore holes were recently completed for a total of 3,891 metres, targeting extensions to mineralised structures north and south of the Golden Bracelet area.

The program returned encouraging results such as 15 metres at 1.04 grams per tonne from 42 metres in hole 25SWAC178 and 19 metres at 0.98 grams per tonne from 68 metres in hole 25SWAC171.

These intersections expand the known mineralised footprint to over 200 metres.

Planning is now underway for follow-up RC drilling at Side Well South to infill current spacing and support estimation of an initial mineral resource.

At the same time, RC drilling is continuing at Eaglehawk to define grade distribution along known structures.

A second RC rig will mobilise to Side Well in late August to accelerate regional and resource-focused drilling.

What are the next steps toward mining approval at Ironbark?

Following the release of the Ironbark Scoping Study, the company is actively progressing development workstreams to prepare for a mining application.

These include hydrogeological assessments, waste characterisation studies, and site layout design, all of which are essential components of the regulatory approval process.

The recent drilling of four water monitoring bores, including the high-grade 25IBMB003 intersection, supports the baseline data required for environmental submissions.

“Development workstreams currently underway as part of our plan to lodge a mining application will continue, however the Company will be updating the mineral resource for Ironbark once the full extent of mineralisation has been defined, with any increase in the resource having strong potential to improve the economics for a mining operation at Ironbark.”

Additional RC drilling is being planned to support both geological modelling and mine planning as part of the transition from exploration into project development.

Drilling growth supports long-term strategy

With high-grade extensions now defined south of Ironbark, strong early-stage intercepts at Side Well South, and permitting work advancing, Great Boulder Resources is well positioned to continue building value through both discovery and development.

The combination of ongoing exploration planned resource updates, and early-stage mining studies demonstrates the company’s clear intent to transition Ironbark into a viable gold operation.

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