Barton Gold Hits 32.4 g/t at Tunkillia, Dwarfing Pit Grade Model

Drill holes at a South Australian gold project are returning 4-6 g/t gold across meaningful widths, with one metre-scale hit grading 32.4 g/t. The pit those holes sit inside was modelled on an average grade of 1.05 g/t.

That gap is the story.

The intersections come from Barton Gold’s Phase 2 infill drilling programme at its Tunkillia project, designed to upgrade JORC resource classification within the proposed S1 and S2 starter pits ahead of a Pre-Feasibility Study targeted for Q1 2027. The results feed directly into the company’s economic modelling, which projects roughly $1.8 billion in operating profit across the first 2.5 years of production at current gold prices, according to figures anchored in a May 2025 scoping study.

High-grade drill hits are one thing. Turning them into a validated resource that supports a multi-billion-dollar projection is another.

Here is what the numbers show, what they do not yet prove, and what comes next.

Grade gap: what Barton’s Phase 2 holes are actually returning

The strongest hits do not sit at depth or on the fringes. They sit shallow, inside pit shells that current economics already assume.

Hole TKB0703 returned 24 m at 4.51 g/t gold from just 47 m depth, including a 2 m sub-interval grading 16.7 g/t. That is a broad, high-grade intersection close to surface, the kind of ounce profile that tends to front-load cash flow.

Hole TKB0678 followed with 11 m at 5.51 g/t from 14 m depth, carrying a 2 m sub-interval at 24.7 g/t. Then came the peak grade: 6 m at 6.61 g/t from 70 m, including 1 m at 32.4 g/t from 73 m depth.

Supporting intervals filled out the picture. Barton reported 11 m at 2.87 g/t from 79 m (including 1 m at 10.6 g/t), 5 m at 4.76 g/t from 67 m in hole TKB0496, and 19 m at 1.72 g/t from 132 m.

These holes targeted a newly identified high-grade domain within the existing pit shells, not step-out or greenfields ground.

Barton on the grades Managing director Alexander Scanlon has characterised the returned grades as exceptional relative to the 1.05 g/t average grade that underpins the starter pit economics.

The read for you is straightforward. In parts of the pit footprint, drilling is returning grades four to six times the modelled average, which suggests the resource model built into current economics may be materially conservative in at least some zones.

What $1.8 billion in projected operating profit actually rests on

The headline number is large. Understanding what sits beneath it is the difference between treating it as a fact and treating it as a modelled scenario.

Barton’s roughly $1.8 billion operating profit projection covers the first 2.5 years of production and is derived from internal modelling at “current gold prices.” That is distinct from the company’s May 2025 Optimised Scoping Study (OSS), which used an explicit A$5,000/oz assumption and produced a $1.3 billion operating free cash figure over the first 27 months.

The scoping study economics rest on a set of metrics that explain why the project attracts attention:

• 73% unlevered, pre-tax internal rate of return (IRR) for the large-scale operation
• Cash costs of approximately $1,235/oz
• Operating cash flow of approximately $2,265/oz gold
• Capital payback in under 12 months
• Starter pits repaying development capital roughly four times over across the first 2.5 years

Those figures also assume starter pit production of 365,000 oz gold and 923,000 oz silver in the first 27 months.

A pre-feasibility study replaces scoping-level assumptions with independent technical verification across capital costs, processing recoveries, and ore reserve grade, and its outputs are the first set of economics that debt and equity financiers will treat as a credible basis for project valuation.

The point for you is the leverage. A low cash cost per ounce means that when the gold price rises, almost all of that increase drops through to margin, which is why the profit projection swings so sharply between scenarios.

The OSS baseline versus the current-prices scenario

The OSS was published in May 2025 at that explicit A$5,000/oz price, producing the $1.3 billion operating free cash figure for the starter pits.

Subsequent releases across June and July 2026 updated this to approximately $1.75 billion to $1.8 billion at “current prices.” Crucially, those releases did not specify a per-ounce gold price behind the higher figure.

That matters because the $1.8 billion number is the most gold-price-sensitive version of the forecast Barton has published. Without a disclosed price assumption, you cannot independently reconstruct it, and it rises or falls directly with the Australian dollar gold price.

How the Phase 2 programme feeds the resource upgrade and PFS

Drill results only become economics once they pass through classification and study work. That process is where Tunkillia sits now.

The Phase 2 programme’s primary purpose is to upgrade mineralisation within the OSS-optimised S1 and S2 pit shells from Inferred to Indicated and Measured JORC categories. A JORC resource is classified by confidence level, and only higher-confidence Indicated and Measured material can be converted into ore reserves suitable for a PFS.

JORC resource classification determines which mineralisation can be converted into ore reserves suitable for a PFS, with only Indicated and Measured categories meeting the confidence threshold that underpins bankable feasibility work.

The programme has grown. Original Phase 2 scope covered 38,760 m of RC and diamond drilling across 311 holes, taking the combined Phase 1 and Phase 2 total to 57,653 m. Barton has since expanded the overall programme to approximately 70,000 m RC and 3,000 m DD, scheduled to conclude during September 2026.

The sequence of milestones ahead runs as follows:

1. Final Phase 2 assay batch, expected to be reported shortly and not yet incorporated into any revised resource estimate
2. Updated Mineral Resource estimate, anticipated within the coming months
3. Pre-Feasibility Study, targeted for Q1 2027
4. Mining lease application, to follow PFS completion

Alongside the drilling, Barton is running parallel workstreams: environmental and cultural heritage surveys, infrastructure assessments, financing reviews, renewable energy evaluation, and preparations for the mining lease application.

Next study milestone Barton is targeting a Pre-Feasibility Study for Q1 2027, the point at which independent technical work replaces internal modelling.

The expanded scope tells you something about approach. Adding drilling beyond the original Phase 2 target suggests Barton is building data density before the PFS rather than rushing the study, which lowers the risk of a weaker resource classification outcome but pushes definitive economics further out.

High-grade hits within an unproven resource: where the risks sit

Strong drill results do not remove risk. They change which risks matter most, and for a pre-PFS junior developer, several sit squarely in view.

• Resource estimate uncertainty. Current economics rest on OSS-level modelling, and the pit shells targeted by Phase 2 remain predominantly Inferred. The economic models depend on a resource conversion that has not yet occurred.
• Gold price sensitivity. The 73% IRR and roughly $1.8 billion operating profit figure are modelled at or above A$5,000/oz. A low-cash-cost operation is highly leveraged, so a material fall in the Australian dollar gold price would cut both figures significantly.
• Execution and permitting. Barton still needs to complete the expanded drilling, publish the PFS, secure a mining lease, and arrange construction financing. Each step carries schedule and outcome risk.

Edison Investment Research, in 2025 notes on Barton Gold, emphasised the project’s low cash costs and strong early operating cash flow as investment appeal anchors, while flagging its dependence on the successful completion of further studies.

South Australian mining reforms enacted through 2026 affect the regulatory environment through which projects like Tunkillia must navigate permitting, and the mining lease application Barton has flagged as a post-PFS step sits within a licensing framework that has seen significant legislative change.

A 73% IRR is a compelling headline, but it is a scoping-level calculation built on preliminary assumptions. The read for you is that the PFS will be the first point at which the market can treat Tunkillia’s economics as independently validated rather than internally modelled.

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, and financial projections are subject to market conditions and various risk factors.

What the Tunkillia story needs to prove in the next 12 months

The high-grade thesis now enters a period where it either gets validated at resource level or stays a compelling but unconfirmed drilling result.

The updated Mineral Resource estimate is the first concrete test. If Phase 2 data lifts the classified resource grade within the pit shells, the economics move closer to PFS-grade credibility. If it does not, the current projections remain built on drilling optimism rather than a confirmed resource base.

The PFS, targeted for Q1 2027, is the moment internal modelling gives way to independent technical validation. Its outputs on capital costs, recoveries, and reserve grade will determine whether the $1.8 billion projection survives contact with rigorous assumptions.

Here are the specific watch-points over the next 12 months:

• The updated Mineral Resource estimate, anticipated within months of the final Phase 2 assay batch
• The PFS delivery, targeted for Q1 2027
• The mining lease application, to follow PFS completion
• The Australian dollar gold price trajectory, which remains elevated as at September 2026 and provides a supportive backdrop for the study programme

Understanding what each milestone will and will not prove leaves you better placed to assess Barton’s announcements as they arrive, rather than reacting to headline figures without a framework for weighing them.