Brightstar Doubles Two Mile Hill Gold Resource to 1.45 Moz

Roughly 700,000 ounces of gold added to a single deposit at a discovery cost of $6 per ounce. In the current Western Australian exploration environment, where finding new ounces rarely comes cheap, that combination is the sort of number that makes a resource announcement worth a closer look.

That figure sits at the centre of Brightstar Resources’ updated estimate for its Two Mile Hill-Shillington deposit, released on 28 September 2026. Drilling only began at the deposit in April 2026, yet the resource has nearly doubled in the space of a single update.

The speed of that build is the reason this warrants investor attention today, not next quarter.

What follows below breaks down what the upgraded resource means for how the deposit gets developed, what the newly defined Shirvington Zone adds to the upside case, and where the Sandstone project now sits as a Western Australian gold asset heading into a pre-feasibility study.

Nearly doubling overnight: what the Two Mile Hill resource upgrade actually shows

The updated Mineral Resource Estimate (MRE) for Two Mile Hill-Shillington now stands at 24.6 million tonnes at 1.8 g/t Au for 1.45 million ounces. A JORC Resource is a concentration of minerals classified by confidence level, from Inferred through Indicated to Measured, with reasonable prospects for eventual economic extraction.

The prior estimate, dated August 2026, sat at 14.6 million tonnes at 1.6 g/t Au for 731,000 ounces. That is a 98% uplift in contained ounces from one update to the next.

The comparison lands harder in a table.

The headline ounce count is one thing. The confidence-classified portion is another, and it matters more for feasibility work.

The Indicated resource grew by 177% to 526,000 ounces at 1.6 g/t Au. Indicated material carries enough geological confidence to underpin feasibility studies, so growth in that category tells you the ounces are becoming more bankable, not just more numerous.

The intercepts behind the numbers

The resource growth was achieved through a programme of infill and extensional drilling that probed the tonalite host rock at greater depth and across a broader lateral extent. Representative intercepts folded into the estimate include 112.6 metres at 1.02 g/t Au from 246.9 metres depth and 172.5 metres at 1.00 g/t Au from 301.5 metres depth.

The metric that should catch an investor’s eye is the discovery cost: roughly 700,000 additional ounces added at an estimated $6 per ounce. That figure measures how efficiently drilling expenditure converts into resource ounces, and it sits well below the benchmarks typical for resource additions of this scale.

“A major milestone for the Sandstone project,” is how Brightstar managing director Alex Rovira characterised the updated estimate.

Underground majority confirmed: why the September estimate changes the development conversation

The bigger structural signal in the September MRE is not the total ounce count. It is where those ounces sit.

The underground portion of Two Mile Hill now stands at 20 million tonnes at 2.0 g/t Au for approximately 1.3 million ounces. That is the majority of the total 1.45 Moz deposit, and it changes the kind of feasibility thinking the project requires.

An open-pit-first deposit scopes differently from an underground-majority one. The latter demands mine designs, access decisions, and capital assumptions built around extracting ore from depth rather than stripping it from surface.

Here is the operating context in brief:

• Underground component: 20 Mt at 2.0 g/t Au (~1.3 Moz)
• Total Two Mile Hill-Shillington deposit: 1.45 Moz
• Sandstone pre-feasibility study (PFS) targeted for 2H CY2026
• Updated group MRE targeted before end of CY2026
• Four rigs active across Sandstone

The grade detail is the counterweight to the added complexity. The underground component runs at 2.0 g/t Au against a whole-deposit average of 1.8 g/t Au, consistent with the grade improving at depth. Higher grade underground is what makes the economics of deeper mining stack up.

Wide, unconstrained intercepts underpinned the case, including 305.4 metres at 1.82 g/t Au and 226 metres at 3.11 g/t Au, with holes ending in mineralised tonalite. For an investor tracking the development timeline, the read is straightforward: the PFS is now scoping a materially larger and deeper project than the one first envisioned when the study was announced. The feasibility inputs have shifted, and shifted upward.

What the Shirvington Zone adds, and what it does not yet confirm

Deep diamond drilling in August 2026 turned up something the September MRE did not even count. The Shirvington Zone is a deep extension of the Two Mile Hill tonalite, and its geometry alone is worth attention.

The mineralised tonalite is interpreted as more than 300 metres wide horizontally at approximately 700 metres below surface, open at depth, and sitting roughly 250 metres below the current MRE boundary. Both drill holes that tested it failed to exit the intrusion.

The geometric specifications:

• Tonalite width: greater than 300 metres horizontal at approximately 700 metres depth
• Distance below current MRE boundary: approximately 250 metres
• Both holes failed to exit the mineralised tonalite
• Zone formally defined in Brightstar’s 24 August 2026 ASX announcement

Then there is the gold you can see. Across the two deep holes, Brightstar logged 53 individual visible-gold occurrences, generally within quartz veins alongside galena and pyrite. The grains are small, generally less than 1 mm, and visually estimated at less than 0.01% of the mineralised zones.

Fifty-three visible-gold hits is the kind of detail that fuels speculation. Brightstar was careful to head that off.

Brightstar cautions that visual observations cannot substitute for laboratory assays.

That caution matters, because both Shirvington holes were left out of the September 2026 MRE. Assay results remain pending, which means the zone’s grade, continuity, and economic significance are unconfirmed.

The takeaway for investors is calibrated rather than speculative. The scale of the geometry, a body more than 300 metres wide that neither hole exited, signals that meaningful further upside is geologically plausible. Until the assays land, though, Shirvington is best treated as a prospective extension, not a resource increment. Those pending results are the near-term catalyst to watch.

Sandstone at 3.6 million ounces: where the Brightstar group resource now stands

Step back from the deposit detail and the pace of value creation across a single drilling campaign comes into focus.

The Sandstone gold project now carries a total resource of 79 million tonnes at 1.4 g/t Au for 3.6 million ounces, including 1.5 million ounces in the Indicated category. Two Mile Hill-Shillington, at 1.45 Moz, is the dominant contributing deposit within that total.

The group picture is larger still. Across all assets, Brightstar’s total resource stands at 110 million tonnes at 1.5 g/t Au for 5.2 million ounces.

What tells the story best is the Sandstone trajectory over five months.

That is a move from 2.4 Moz in May to 3.6 Moz in September, delivered through successive upgrades rather than a single lucky result. Further exploration is planned across regional Sandstone prospects considered geologically comparable to Two Mile Hill, and an additional update is expected before the end of CY2026 as Shirvington assays are integrated.

At 3.6 Moz and still expanding, Sandstone has crossed into the multi-million-ounce territory that draws institutional and M&A attention in the Western Australian gold sector. The group figure of 5.2 Moz frames Brightstar as a company with scale beyond a single project.

What the 1.45-million-ounce result means for Brightstar’s next twelve months

The confirmed MRE, the pending Shirvington assays, and the PFS timeline combine into a forward picture defined by a dense run of scheduled information releases rather than a pause after the result.

Three near-term catalysts sit in sequence:

1. Shirvington assay results, pending as of 28 September 2026, which will confirm or challenge the visible-gold case at depth.
2. Updated group MRE, targeted before the end of CY2026, incorporating those assay results.
3. Sandstone pre-feasibility study, targeted for 2H CY2026, which will translate the resource into a development plan.

The September MRE feeds directly into the active underground mining studies, so the feasibility inputs are now materially upgraded against the study’s starting assumptions. With four rigs still turning across Sandstone, the resource picture is not settled.

The key risk sits with the PFS itself. The development path remains contingent on metallurgical testwork, cost estimates, and scheduling that are not yet public. A larger, deeper, underground-majority project is more complex and potentially more capital-intensive to build.

For an investor, the read is that the next three to six months carry a high density of catalysts, each capable of moving the resource and development picture again. This is a transition point for the project, not a resting one.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions.

Past performance does not guarantee future results. Financial projections are subject to market conditions and various risk factors. Forward-looking statements regarding the pre-feasibility study, pending assays, and resource updates are speculative and subject to change based on market developments and company performance.