Amex Gold Mining’s 114% IRR: Exceptional or Assumption-Driven?

A junior miner is claiming a six-month capital payback and an all-in sustaining cost of roughly US$910 per ounce, figures that would put it in the same conversation as established mid-tier producers. It has not yet poured a single ounce of commercial gold.

Those numbers come from a feasibility study published on 13 April 2026. The company backing them, formerly Amex Exploration, rebranded to Amex Gold Mining in July 2026, and in September began cutting a ramp into the Quebec rock. As of 21 September 2026, that ramp had advanced more than 75 metres underground.

The rebrand is not cosmetic. It signals a company repositioning itself for capital markets as a producer-in-waiting, and it puts the Perron project’s economics under a brighter light. What follows here is a way to judge whether the headline figures are structurally justified or leaning on assumptions that deserve scrutiny, covering the phased architecture, the cost advantages behind the AISC, and the execution risks that have derailed comparable projects.

What the Phase 1 feasibility numbers actually say

Start with the two figures that anchor everything else. The Phase 1 feasibility study reports an after-tax internal rate of return of 114.6% and an after-tax payback of roughly six months from first commercial production.

The headline economics After-tax IRR of 114.6% and a payback period of approximately six months. These are the numbers that frame everything else in the study, and everything else depends on the assumptions that produce them.

Both figures rest on a gold price assumption of US$3,500 per ounce. That single input does an enormous amount of work in the model, and no disciplined reading of these economics can skip past it.

Here is the structure that generates the cash flow. Phase 1 is a five-year underground toll-milling operation running at approximately 1,100 tpd, producing about 147,000 ounces of gold annually from the high-grade Champagne Zone. There is no on-site mill, no tailings facility, and no open pit in the plan.

The toll-milling design matters for the payback maths. Ore mined before the company formally declares commercial production (defined as sustained throughput of 660 tpd) generates revenue that is not counted against capital expenditure. At an assumed US$3,500/oz, those pre-production revenues substantially offset net capex, which is what compresses the effective payback from a conventional multi-year recovery cycle down to months.

The reserve base underpinning Phase 1 stands at 1,989 kt grading approximately 12.1 g/t Au, containing 774 koz on a proven and probable basis, effective 1 April 2026 and reported under NI 43-101 standards.

Here is the read you should take. These metrics are genuinely exceptional by feasibility-study standards, but their quality can only be judged against the inputs behind them. The six-month payback is only as credible as the US$3,500/oz price holding and the 12.1 g/t grade surviving real mining conditions. Both are doing heavy lifting simultaneously, and a shortfall in either would lengthen the timeline the headline figure advertises.

AISC margins across producers have widened significantly in 2026 as gold prices elevated, which is the market context that makes a sub-US$1,000/oz cost structure at Perron look genuinely competitive rather than simply impressive relative to feasibility-study norms.

The structural advantages that make the economics possible

The low AISC and rapid payback are not lucky outcomes. They are the product of deliberate design choices, and understanding the architecture is what lets you assess whether the economics are durable.

Four structural decisions carry most of the weight:

The global average AISC benchmark rose to approximately US$1,785 per ounce in Q1 2026 according to World Gold Council data, which puts Amex’s feasibility-study figure of US$910 per ounce roughly half the industry average and underscores why that cost structure, if it survives construction, would represent a material competitive advantage.

• Sub-5,000 tpd throughput keeps Phase 1 below the federal threshold that triggers more intensive Canadian environmental review, with permitting targeted for mid-2028.
• The toll-milling model removes the on-site processing plant, tailings facility, and open-pit build from the Phase 1 capital budget entirely.
• Hydroelectric power from Hydro-Quebec is available at roughly US$5.5 cents per kWh, among the lowest industrial rates in North America.
• CMAC-Thyssen, an established Quebec mining services contractor, provides underground development capability without the ramp-up risk of an unproven team.

Permitting architecture and the 5,000 tpd design choice

Phase 1 runs at 1,100 tpd, well below the 5,000 tpd federal threshold. Staying under that line means the project avoids the more complex federal environmental assessment that a larger operation would attract, with permitting targeted for mid-2028 and potential for earlier approval.

The absence of on-site tailings is a specific simplifier in the Quebec context. No tailings facility means one fewer major permitting workstream and one fewer long-term environmental liability to manage.

Phase 2 changes that calculus. A full-scale build with a dedicated mill, tailings management, and open-pit operations would push throughput and environmental exposure into far more demanding regulatory territory, which is why the phased approach front-loads the simplest economics first.

Power cost and infrastructure proximity

Underground mining is energy-hungry. Ventilation, hoisting, and dewatering run continuously, and power is a structural line item rather than a marginal one.

At approximately US$5.5 cents per kWh, Perron’s electricity cost sits materially below jurisdictions relying on gas or coal-fired power. An electrical substation roughly 6.5 km from site keeps grid connection costs to an estimated CAD$7.7 million per the feasibility study.

This is a direct input into the US$910/oz AISC, not background colour. Low-cost, low-carbon hydro power also strengthens the project’s ESG positioning, which matters to institutional lenders and investors who weight carbon intensity in their capital decisions. The question worth carrying forward is whether these advantages scale into Phase 2 or remain specific to the current configuration.

What the bulk sample and ramp construction actually de-risk

Paper economics are one thing. What is happening in the ground right now is another, and the ramp advance is the first real-world evidence the market has.

The 40,000-tonne bulk sample is not a preliminary drill-and-test exercise. It is the mechanism by which Amex tests whether the 12.1 g/t reserve grade survives dilution and stope geometry under actual mining conditions, which is the single most important validation before Phase 1 commercial production.

The construction milestones give a concrete timeline. Portal construction was completed and the first ramp blast fired in early September 2026. As of 21 September 2026, the ramp had advanced more than 75 metres underground, targeting approximately 235 m vertical to reach the Champagne Zone, with CMAC-Thyssen handling development.

Here is the detail that separates this from a typical pre-feasibility test. The ramp is being built to production-scale dimensions consistent with Phase 1 requirements. That means the capital being spent now converts directly into commercial infrastructure rather than becoming sunk cost, and it serves both the bulk sample and later mining without a rebuild.

The near-term marker Amex anticipates intercepting ore via the ramp within approximately one year of September 2026, placing the first grade reconciliation data in roughly the Q3-Q4 2027 window.

The three-stage development sequence frames the whole project:

1. Bulk sample program (underway): 40,000 tonnes, fully permitted, testing grade continuity, dilution, and metallurgy at production scale.
2. Phase 1 toll-milling (first revenue targeted 2028): five years of commercial production at ~1,100 tpd with no on-site processing.
3. Phase 2 full-scale build (feasibility anticipated 2029-2030): dedicated mill, tailings, and open-pit operations.

For context, the broader project holds approximately 1.615 million ounces of measured and indicated resources at 6.14 g/t Au, with the Champagne Zone forming the high-grade core feeding Phase 1. The bulk sample cost is roughly US$60 million in total, a substantial portion already invested and included in the overall capital budget.

For anyone tracking this transition, the bulk sample completion and its grade reconciliation data are the most important near-term catalysts. They are the point at which the feasibility economics either gain real-world validation or reveal a gap, ahead of the Phase 1 permitting and financing decisions.

Where this project fits among Canadian junior-to-producer transitions, and what can go wrong

High-grade underground juniors have a track record, and it is not uniformly kind. Mapping Amex against the documented failure modes is more useful than pronouncing a verdict.

Industry case studies, including PureGold at Red Lake and Wesdome’s Kiena restart, point to recurring pressure points. Grade control and dilution problems in narrow high-grade veins pull realised head grades below feasibility assumptions. Capex and schedule overruns force emergency financings. Ramp-up underperformance delays cash flow and stretches balance sheets.

Grade dilution in narrow veins has ended more than one high-grade underground project in Canada, with the True North case standing as the clearest recent example of how quickly realised head grades can diverge from reserve assumptions and destroy the economics a feasibility study was built on.

Amex has live exposure to each. The US$3,500/oz gold price assumption sits materially above long-term analyst consensus. The Champagne Zone is high-grade but geometrically constrained, sensitive to stope design and dilution control. And the toll-milling model depends on securing third-party mill access on terms consistent with the feasibility model.

The mitigants are real. The 12.1 g/t reserve grade is high enough that even with typical narrow-vein dilution the project likely stays economic. The production-scale bulk sample tests grade continuity before full commitment. And the compressed capex means the six-month payback has room to absorb moderate grade or price variance.

Drill intercepts cited from the Champagne Zone, including 213.11 g/t Au over 3.75 m and 25.19 g/t Au over 32.80 m, point to robust high-grade mineralisation, though these figures are unverified in this context and should be treated as indicative only.

The variable to stress-test The US$3,500/oz gold price assumption sits materially above long-term analyst consensus. Before forming a commercial view, model the economics at prices closer to consensus and see how the payback and AISC respond.

The grade buffer is substantial enough to survive ordinary dilution. The price assumption is the input that deserves your own scrutiny. Investors who can map these failure modes onto Amex’s position are best placed to identify the two or three bulk sample data points that will most meaningfully confirm or challenge the study, with the Phase 2 feasibility due around 2029-2030 and Indigenous community agreements in active preparation.

The investment case in a single framework: what to watch before Phase 1 permitting

The analysis reduces to a short watchlist. Over the next 12 to 18 months, a handful of data points will do more to validate or challenge the feasibility economics than any amount of modelling.

Near-term catalyst timeline

• Bulk sample grade reconciliation (ore intercept ~Q3-Q4 2027): the first real-world test of whether 12.1 g/t survives production-scale stope dimensions. This is the single most critical catalyst.
• Indigenous community agreements (in active preparation): joint announcements planned; a prerequisite for smooth permitting and social licence.
• Bi-weekly drilling and development updates (ongoing): incremental read on grade continuity and ramp progress.
• Phase 1 permitting decision (mid-2028 target): confirmation that the sub-5,000 tpd structure delivers the timeline advantage the model assumes.

The grade reconciliation matters most because it is the point where the model meets the rock. Everything else in the feasibility study flexes off whether that 12.1 g/t grade holds under real mining.

Why the current gold environment makes the timing relevant

With gold at elevated levels and the study’s US$3,500/oz assumption sitting materially above long-term analyst consensus, the price gap between assumption and reality is a key variable to monitor. Combined with Quebec’s structural power-cost advantage, that creates a specific window for evaluating this junior-to-producer transition, without needing to make a directional call on where gold heads next.

Miner quality differentiation becomes most legible during gold rallies, when high-AISC producers absorb the price uplift to reach breakeven while low-cost operators convert it directly into margin, which is the sector dynamic that makes Perron’s cost structure particularly relevant to evaluate at current gold prices.

The next 12 months of ramp and bulk sample data are where the most meaningful de-risking will either happen or fail to. That is the window in which this investment case is most directly testable.

Investors exploring how junior-to-producer transitions like Amex fit into a broader portfolio framework will find our full explainer on commodity cycle investing in mining stocks covers position sizing and catalyst-driven entry strategies for high-conviction resource transitions.

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 permitting timelines, production targets, and project economics are speculative and subject to change based on market developments and company performance.