This page was created by Thunder Gold Corp. All statements about mineral resources refer to the January 19, 2026 NI 43-101 mineral resource estimate prepared by Micon International Limited. Mineral resources are not mineral reserves and do not have demonstrated economic viability.
Gold exploration feasibility study
| An exploration-stage feasibility study is the most advanced economic study a gold project can complete before a construction decision, and it is often confused with the less advanced studies that come before it. Thunder Gold Corp (TSXV: TGOL | OTCQB: TGOLF | FSE: Z25) is advancing the Tower Mountain gold project about 40 km west of Thunder Bay, Ontario, and its studies are still ahead of it: the company is targeting an updated mineral resource estimate in Q4 2026 and an initial preliminary economic assessment in Q4 2026 or Q1 2027, with pre-feasibility in 2027 or later. This section explains where a gold exploration feasibility study sits in that sequence. It is general information, not investment advice. |
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What a Gold Exploration Feasibility Study Is, and Is Not
A feasibility study is an engineering-level assessment of whether a defined deposit can be mined profitably. It establishes mineral reserves from mineral resources, designs the mine and processing plant, estimates capital and operating costs at a defined level of accuracy, addresses infrastructure, water, tailings, closure and permitting, and issues a recommendation to the board. It is not a guarantee of anything. It does not grant a permit, raise the money or remove geological and market risk, and its conclusions are only as good as its inputs: drilling density, metallurgical testwork, cost assumptions and the gold price used.
What a Study Does Not Prove
A study is a technical view of one set of assumptions on one date. Change the gold price assumption and the pit shell, the cut-off grade and the mineable tonnage all change with it. Change the recovery or the strip ratio and the operating cost moves. A study therefore describes a scenario, which is why independent qualified persons are required to prepare or supervise it, and why the underlying data must be traceable to drill results and testwork.
The Study Ladder from Resource Estimate to Feasibility
Studies build on each other, and each one raises confidence rather than certainty.
| Study | What it does | Resource basis | Confidence |
|---|---|---|---|
| Mineral resource estimate | Estimates tonnage and grade | All reported categories | Geological estimate only |
| Preliminary economic assessment | Conceptual economics, first mine concept | Indicated plus Inferred | Conceptual, not a reserve |
| Pre-feasibility study | First serious engineering case | Measured and Indicated | A reserve becomes possible |
| Feasibility study | Construction-level engineering | Measured and Indicated | Reserve at high confidence |
A nuance that matters for investors: an initial preliminary economic assessment may include Inferred material in its mining schedule precisely because it is a conceptual study. A pre-feasibility or feasibility study cannot convert that material into reserves. This is why a large Inferred resource and a strong preliminary study do not automatically become an economic mine. The ounces have to be upgraded by further drilling and better geological confidence first.
The ladder also explains why newsflow is sequenced. An updated resource estimate usually comes before an economic study, because the study needs the newest tonnage and grade in order to model a pit. Drilling programmes and studies therefore compete for the same budget, and a company has to decide each year how much to spend on expansion drilling and how much on engineering.
Why Metallurgy and Cost Assumptions Decide the Outcome
Two technical inputs drive most of the variance between a good study and a weak one: recovery and ore hardness. At Tower Mountain, 16 representative samples covering all lithologies and alteration types returned gold recoveries of 68% to 94.9%, averaging about 85%, while the mineral resource estimate assumed a more conservative 80% recovery. Deportment work found that 80% to 100% of the gold is native gold, with the remainder as electrum, gold-telluride (petzite) and gold-stibnite. Acid-base accounting returned a net neutralising potential of 76.5 kg CaCO3 per tonne, indicating that acid drainage is unlikely. Bond work index is around 20 kWh/t, which is hard ore and will influence comminution design and power draw in any future study.
What Thunder Gold Has Completed and What Remains a Target
Completed work is straightforward to state. The mineral resource estimate effective January 19, 2026, prepared by Micon International Limited with qualified persons William Lewis, P.Geo., Charley Murahwi, P.Geo., FAusIMM, and Tudorel Ciuculescu, P.Geo., reported 34.0 Mt Indicated at 0.46 g/t Au (514,000 oz) and 211.1 Mt Inferred at 0.45 g/t Au (3,053,000 oz) at a 0.19 g/t Au cut-off, using a US$3,000 per ounce gold price assumption. Project-to-date drilling totals 235 holes for roughly 47,000 m, and the modelled strip ratio is 1.8:1. Everything beyond that is a target: an updated resource estimate in Q4 2026, an initial preliminary economic assessment in Q4 2026 or Q1 2027, and pre-feasibility in 2027 or later. Mineral resources are not mineral reserves and do not have demonstrated economic viability. No mining permit exists at Tower Mountain, and permitting has not been applied for or granted. The full NI 43-101 technical report and company documents set out the detail, while Tower Mountain geology and drill results explain the data behind the estimate.
How to Read a Feasibility Study as an Investor
- Check the effective date and the gold price assumption before the headline numbers.
- Compare modelled recovery against the metallurgical testwork, not against the base case alone.
- Look at how much of the mine plan relies on Inferred material.
- Read initial capital, sustaining capital and closure cost together.
- Confirm whether reserves are stated, and on which resource categories they rest.
- Check what the study excludes, such as full permitting and financing.
Finally, read the study against the company’s earlier studies and against peer projects. A rising cut-off grade, a falling strip ratio, or a recovery assumption that drifts upwards without new testwork are all worth questioning. A study that cannot be reconciled with its own technical report has a disclosure problem, not only a technical one.
Every milestone described here remains a company-stated target rather than completed work, and exploration and development-stage investing is high risk.
Frequently Asked Questions
Q: What is a gold exploration feasibility study?
A: It is an engineering-level study that determines whether a defined gold deposit can be mined profitably. It establishes mineral reserves from mineral resources, designs the mine and plant, estimates costs and addresses infrastructure, water, tailings, closure and permitting before a construction decision.
Q: What is the difference between a PEA and a feasibility study?
A: A preliminary economic assessment is conceptual and may include Inferred material in its mine schedule. A feasibility study works from Measured and Indicated resources, reaches construction-level engineering confidence, and is the study that can support a formal reserve and a build decision.
Q: Why does metallurgical recovery matter so much in a study?
A: Recovery determines how much of the contained gold is actually payable. At Tower Mountain, 16 samples returned recoveries of 68% to 94.9%, averaging about 85%, while the resource estimate assumed 80%. A lower assumed recovery reduces modelled revenue for the same tonnage and grade.
Q: Has Thunder Gold completed a feasibility study at Tower Mountain?
A: No. Thunder Gold is targeting an updated mineral resource estimate in Q4 2026 and an initial preliminary economic assessment in Q4 2026 or Q1 2027, with pre-feasibility in 2027 or later. These are company-stated targets, and no mining permit exists or has been applied for.
Q: Does a positive feasibility study mean a mine will be built?
A: No. A study is a technical and economic assessment, not a permit or a financing commitment. Permits, environmental approvals, First Nation engagement, funding and market conditions all still have to be satisfied, and mineral resources are not mineral reserves until an appropriate study supports that conversion.
Gold project development
| Gold project development follows a sequence that is broadly the same everywhere, even though the timelines are not. Thunder Gold Corp (TSXV: TGOL | OTCQB: TGOLF | FSE: Z25) is at the beginning of that sequence at its Tower Mountain gold property about 40 km west of Thunder Bay, Ontario, where the company is targeting an updated mineral resource estimate in Q4 2026 and an initial preliminary economic assessment in Q4 2026 or Q1 2027. This section sets out the order in which gold project development normally proceeds, and how existing infrastructure at Tower Mountain may shorten parts of it. It is general information, not investment advice. |
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The Gold Project Development Sequence, Stage by Stage
Development is not one decision. It is a chain of studies, designs and permits, and each stage produces a deliverable the next stage depends on.
| Stage | Main deliverable | Depends on |
|---|---|---|
| Economic study | Conceptual mine and cost model | Mineral resource estimate |
| Mine design and metallurgy | Pit design and process flowsheet | Testwork and drilling density |
| Engineering and feasibility | Construction-level design | Updated resource and cost study |
| Environment and permitting | Closure plan and approvals | Environmental baseline work |
| Construction and commissioning | A built, operating mine | Financing and permits |
Site Access and Early Works
Access determines how expensive everything after it becomes. A project about 3 km from the Trans-Canada Highway 11/17, and about 40 km from Thunder Bay, can be explored and later developed without building a permanent camp or a long access road, and its workforce can live at home. At Tower Mountain the property boundary sits roughly 3 km south of the highway, with rail and power corridors 3 to 5 km away and the international port of Thunder Bay providing Saint Lawrence Seaway access. Those are construction and logistics advantages rather than exploration advantages, but they matter enormously in a study.
Metallurgy and Process Design
Process design follows testwork. At Tower Mountain, 16 representative samples spanning all lithologies and alteration types returned gold recoveries of 68% to 94.9%, averaging about 85%, while the resource estimate assumed 80%. Deportment work indicates that 80% to 100% of the gold is native gold, with the balance as electrum, gold-telluride (petzite) and gold-stibnite. A Bond work index of around 20 kWh/t signals hard ore, which shapes crusher and mill selection, power draw and grinding circuit design. Acid-base accounting returned a net neutralising potential of 76.5 kg CaCO3 per tonne, a favourable early signal on acid drainage.
Mine Plan, Strip Ratio and Pit Optimisation
The mine plan decides how much waste rock must be moved for each tonne of ore. Tower Mountain’s modelled strip ratio is 1.8:1, which compares favourably with the peer figures the company publishes for other projects. Pit slope assumptions, 30 degrees in overburden and 50 degrees in fresh rock in the resource model, drive both the pit shell and the waste volume, and the resource was optimised as an open pit and re-blocked at 10 x 10 x 10 m blocks. A lower strip ratio means less waste movement per ounce and usually lower operating cost in the early years.
Tailings, Water and Closure Planning
Tailings and water management are the engineering disciplines that most often change a project footprint and cost. The design question is how to store processed material, manage contact water, and close the site so that it remains physically and chemically stable after mining. The early geochemical signal at Tower Mountain is favourable, with a net neutralising potential of 76.5 kg CaCO3 per tonne from acid-base accounting, meaning acid-generating drainage is considered unlikely. Baseline environmental data, water quality modelling and a closure plan would still be required before any permit could be issued.
Permitting Under the Ontario Mining Act
Ontario has long-established mining law and a defined process. Early exploration work is carried out under exploration permits and mining claims. A producing mine needs a mining lease and an approved closure plan filed under the Ontario Mining Act, alongside provincial and federal environmental assessment requirements where they apply, and consultation obligations with First Nations. Investors should be clear about where a project actually stands: at Tower Mountain, mineral claims are held, but no mining permit exists and permitting has not been applied for or granted.
First Nation Engagement and Community Readiness
Early engagement is both a regulatory expectation and a practical requirement. The Tower Mountain property lies in the traditional territories of Fort William First Nation. The company states that the project has the potential to support more than 1,000 long-term jobs at operation scale, which gives the community conversation a concrete economic dimension. Building durable relationships before a permit application is filed is one of the few development costs that cannot be substituted later, and it shapes the social licence any future mine would need. Engagement agreements are negotiated project by project and their terms are not disclosed in advance, so investors should read early relationship building as progress rather than as a completed approval.
How Existing Infrastructure Shortens the Path
Infrastructure does not remove the need for studies, but it compresses the expensive parts of them. At Tower Mountain, highway, rail and power corridors lie 3 to 5 km from the property, the site is about 40 km from a city of roughly 110,000 people, and the property surrounds the Tower Mountain Intrusive Complex that hosts the gold. Because no camp or permanent road is needed during exploration, more of every dollar goes into drilling, which is how a reported discovery cost of C$3.95 per ounce and all-in drilling costs of roughly C$250 to C$275 per metre were achieved. For a future mine, the same corridor could serve concentrate transport, grid power and equipment delivery without new long-haul construction, although each of those assumptions would have to be tested in detail during engineering studies. Readers can follow the project overview, the NI 43-101 resource estimate and the drill results for the current technical picture. Mineral resources are not mineral reserves and do not have demonstrated economic viability, and every study timeline described here remains a company-stated target rather than completed work. Gold project development at any stage carries substantial risk, and investors can lose most or all of their investment.
Frequently Asked Questions
Q: What are the main stages of developing an open pit gold project?
A: The usual order is an economic study, mine design and metallurgy, engineering and feasibility work, environmental baseline work and permitting, then construction and commissioning. Each stage produces a deliverable that the next depends on, and the schedule varies widely between projects.
Q: Why does site access matter so much to project economics?
A: Access affects every later cost. A project near an existing highway, rail and power corridor avoids building a long access road or permanent camp, keeps construction and haulage costs lower, and can draw a workforce from a nearby city rather than a remote camp.
Q: What permits does a gold mine need in Ontario?
A: Exploration proceeds under exploration permits and mining claims. A producing mine requires a mining lease and an approved closure plan filed under the Ontario Mining Act, plus provincial and federal environmental assessment requirements where they apply and consultation with affected First Nations.
Q: How does the Tower Mountain strip ratio help the project?
A: A modelled strip ratio of 1.8:1 means less waste rock has to be moved for each tonne of ore, which usually lowers operating cost, reduces haulage and fleet requirements, and can improve the early years of a mine plan compared with higher-strip deposits.
Q: Has permitting started at Tower Mountain?
A: No. Thunder Gold holds mineral claims at Tower Mountain, but no mining permit exists and permitting has not been applied for or granted. The updated resource estimate and initial preliminary economic assessment are company-stated targets for Q4 2026 and Q4 2026 or Q1 2027 respectively.