Botnia Gold Fäbodtjärn 2025: what operating reconciliation may suggest about grade, dilution, and technical-report expectations

When a mine starts producing, one of the easiest mistakes is to compare a reserve grade directly with one operating number and assume the answer is obvious.

Usually, it is not.

That is one reason Botnia Gold’s public disclosures around Fäbodtjärn are worth a closer look. Not because they prove one simple point, but because they show how quickly the technical story can become more complicated once real operating data starts to push back on early assumptions. It is also why mining project evaluation & due diligence can matter before the market forms its own view of what the numbers mean.

Botnia Gold Fäbodtjärn 2025 grade dilution disclosure

Fäbodtjärn is useful because it shows how quickly grade, dilution, recovery, and disclosure can stop telling exactly the same story once a mine moves from study assumptions into real production.

Why this case matters

The 2024 updated feasibility study described Fäbodtjärn around 111 kton of indicated mineral resources at 8.5 g/t Au and 85 kton of inferred mineral resources at 5.9 g/t Au. It also described a mine plan in which a small part of the inferred material would still need to be mined for technical reasons, equal to 9.6% of the total tonnage in the plan.

That already matters, because the technical story was never just about one clean reserve number. It was a mine plan, a dilution assumption, a recovery assumption, and a development strategy all moving together.

What the 2024 technical reporting already showed

One practical lesson from Fäbodtjärn is that public technical reporting can start to look messy even before a mine has enough operating history to reconcile it properly.

Inside the 2024 reporting package, the reserve figures are not presented entirely consistently. The main feasibility study works through a reserve case around 121 kton at about 7.39 g/t Au, while the accompanying PERC Table 1 summary refers to 117 kton at 7.7 g/t Au. Another section of the same Table 1 refers to 15% waste dilution and an ore reserve of 127 kton.

That does not automatically invalidate the project. But it does matter for trust. If a technically literate reader has to stop and ask which reserve number should anchor the story, that is already a disclosure issue worth noticing.

Why reserve grade and operating grade are not the same thing

A reserve grade is not the same thing as a realised ROM or plant-feed grade. A realised head grade is not the same thing as recovered gold per treated tonne. And a development year is not the same thing as a stable operating year.

That distinction matters more than many people think.

Once dilution, marginal ore, mining method, stockpiles, campaign timing, and plant performance all start interacting, the operating picture becomes much harder to summarise with one headline number.

What the public 2025 data may be telling you

Botnia Gold reported that it treated 50,000 tonnes in 2025, produced 54,961 tonnes of ore plus 8,643 tonnes of marginal ore, and delivered 224.5 kg of gold during the year.

At the same time, the company also said average recovery for campaigns 4–6 was above 96%, while acknowledging that grade was a challenge during the year and that waste-rock dilution remained high in the high-productivity mining areas.

That combination is what makes this case interesting. Recovery appears better than the 90% assumption used in the 2024 feasibility study, but dilution and grade reconciliation still remained difficult.

What may explain the gap

The most useful question is not “which number is right?”

The more useful question is “what explains the bridge between them?”

In this case, the public record already points to several possible drivers: development ore and marginal ore in the production mix, changing dilution outcomes between mining methods, and real operating learning in the first high-productivity areas.

That story is visible in the reserve updates as well. In February 2025, Botnia Gold increased the dilution assumption in the reserve from 10% to 30% based on early mining experience. In February 2026, the company then increased the mining-loss assumption from 5% to 10% based on actual operating results.

Why this matters for technical disclosure

One of the easiest ways to lose trust in mining disclosure is to let different grade concepts drift together as if they were interchangeable.

They are not.

Reserve grade, mined grade, ROM grade, treated grade, recovered grade, and payable metal can all matter. But they do not answer the same question, and they should not be discussed as if they do.

That is exactly why mining project evaluation & due diligence matters once operating data starts to test the original technical story.

It is also why clear technical reporting to NI 43-101 & JORC (QP/CP) matters. When disclosure around dilution, recovery, reserve assumptions, or operating reconciliation gets blurred, confidence can weaken faster than many teams expect.

A point worth noticing about the CP disclosure

The public PERC documentation states that the Competent Person visited the site during the test-mining campaign in August 2017.

That is not the same as saying there was no site visit. But it does mean the public sign-off appears to rely on a historical site inspection rather than a clearly current site visit tied to the producing-mine phase.

For a mine that moved into real underground production in 2024 and then updated reserves again in 2025 and 2026, some readers may reasonably expect a more current site inspection to strengthen confidence in the public technical sign-off.

What this case teaches in practice

The practical lesson is simple.

When operating results and technical-report language stop lining up neatly, the answer is not to speak more confidently. The answer is to explain the bridge better.

That may mean being clearer about which grade is being discussed, revisiting dilution and mining-loss assumptions sooner, or making it easier for the market to distinguish between study expectations and real operating reconciliation.

That is often where the true quality of technical disclosure shows up.

Need a second technical view when operating data starts to diverge from the study story?

If you are comparing reserve assumptions with actual plant performance, dilution outcomes, or early production results, an independent technical review can help clarify what the numbers are really saying before the market draws its own conclusion.

Contact Gosselin Mining

Further Reading and References

  1. GeoVista AB (online PDF) Vindelgransele Gruvor Uppdaterad Feasibility study, Projekt Fäbodtjärn. Main technical source used for the 2024 updated feasibility-study assumptions, including the stated mineral resources of 111 kton indicated at 8.5 g/t Au and 85 kton inferred at 5.9 g/t Au, the discussion of mining of part of the inferred material for technical reasons, the reserve calculation around 121 kton at about 7.39 g/t Au, and the economic and technical basis of the 2024 mine plan. Available at https://www.botniagold.com/wp-content/uploads/2024/11/GVR24016-Uppdaterad-Genomforbarhetsstudie-Fabodtjarn-2024-09-04.pdf (Accessed on 30 March 2026)
  2. GeoVista AB (online PDF) GVR24016 Uppdaterad Genomförbarhetsstudie Fäbodtjärn – PERC Reporting Standard 2021 Table 1. Main supporting source used for the 2024 PERC-based executive summary, including the stated 117 kton probable reserve at 7.7 g/t Au, the reference to a 2017 CP site visit, the whole-vein mining statement, and other assumptions and disclosures relevant to reserve reporting. Available at https://www.botniagold.com/wp-content/uploads/2024/11/GVR24016-Uppdaterad-Genomforbarhetsstudie-Fabodtjarn-PERC-Reporting-Standard-2021-Table-1-2024-09-04.pdf (Accessed on 30 March 2026)
  3. Botnia Exploration Holding AB (online) Ökade mineralreserver Fäbodtjärn. Main public source used for the 7 February 2025 reserve update, including the increase to 172 kton probable reserve at 7.56 g/t Au, inferred resources of 32 kton at 6.1 g/t Au, and the stated increase in dilution assumption from 10% to 30% based on early mining experience. Available at https://www.botniagold.com/press/okade-mineralreserver-fabodtjarn/ (Accessed on 30 March 2026)
  4. GeoVista AB (online PDF) Ökade mineralreserver för Fäbodtjärngruvan – Table 1. Supporting PERC source used for the February 2025 reserve update, including the executive summary, reserve and inferred-resource figures, and repeated disclosure that the Competent Person site visit took place during the August 2017 test-mining campaign. Available at https://www.botniagold.com/wp-content/uploads/2025/02/okade-mineralreserver-for-fabodtjarnsgruvan-table-1.pdf (Accessed on 30 March 2026)
  5. Botnia Exploration Holding AB (publ) (online PDF) Delårsrapport januari – juni 2025 samt investering i utrustning för malmsortering. Main source used for the Q2 2025 operating discussion, including the high-productivity rill mining phase, the statement that ore-drive mining had been brought below 30% waste dilution, that rill mining had improved but not yet reached the 30% target, and the strategic rationale for investing in ore sorting to reduce waste-rock dilution to 10–20%. Available at https://www.botniagold.com/press/botnia-exploration-holding-ab-publ-delarsrapport-januari-juni-2025-samt-investering-i-utrustning-for-malmsortering/ (Accessed on 30 March 2026)
  6. Botnia Gold AB (online PDF) Delårsrapport januari – september 2025. Used for the Q3 2025 operating context, including the statement that approximately 50,000 tonnes would be treated during 2025, the inclusion of marginal ore in the final campaign, and the company’s discussion of sorting to reduce waste-rock dilution and increase feed grade to the plant. Available at https://www.botniagold.com/press/botnia-gold-ab-delarsrapport-januari-september-2025/ (Accessed on 30 March 2026)
  7. Botnia Gold AB (online PDF) Q4-rapport och bokslutskommuniké januari – december 2025. Main source used for full-year operating data, including 54,961 tonnes of ore produced, 8,643 tonnes of marginal ore produced, 50,000 tonnes treated, and the broader explanation of the 2026 reserve/resource update based on actual production results. Available at https://www.botniagold.com/delarsrapporter/be-q4-bokslutskommunike-2025.pdf (Accessed on 30 March 2026)
  8. Botnia Gold AB (online PDF) Presentation Q4 2025. Supporting source used for operating commentary on campaign 6 and full-year campaign 4–6 results, including the statement that the 50,000-tonne treatment target was reached, average recovery was above 96%, no campaign was below 95%, 224.5 kg gold was delivered during 2025, and grade and side-rock dilution remained operational challenges during the year. Available at https://www.botniagold.com/wp-content/uploads/2026/02/presentation-q4-2025-botnia-gold-ab.pdf (Accessed on 30 March 2026)
  9. Botnia Gold AB (online) Botnia Gold AB – Mineralreserver och tillgångar vid gruvan i Fäbodtjärn. Main public source used for the 4 February 2026 reserve and resource update, including the revised 117 kton probable reserve at 7.06 g/t Au, 30 kton inferred resources at 5.6 g/t Au, the change in mining-loss assumption from 5% to 10%, and the stated 4.9% reduction in total gold content due to the updated assumptions. Available at https://www.botniagold.com/press/botnia-gold-ab-mineralreserver-och-tillgangar-vid-gruvan-i-fabodtjarn/ (Accessed on 30 March 2026)
  10. Botnia Gold AB (online PDF attachment) Reserver och tillgångar. Supporting numerical appendix to the 2026 reserve/resource update, used for the reserve bridge between 1 January 2025 and 1 January 2026, including the depletion effect, revised mining-loss assumption, and the change from 7.39 g/t to 7.06 g/t in the reserve calculation framework. Available at https://www.botniagold.com/wp-content/uploads/2026/02/reserver-och-tillgangar.pdf (Accessed on 30 March 2026)
  11. Gosselin Mining (online) Top 5 disclosure deficiencies of NI 43-101 technical report. Internal related article referenced for the broader discussion of how technical-report quality, assumptions, and disclosure gaps can affect trust once a project reaches the market. Available at https://gosselinmining.com/insights/ni43-101-disclosure-deficiencies/ (Accessed on 30 March 2026)
  12. Gosselin Mining (online) Mining project evaluation & due diligence. Internal service page relevant to the article’s broader discussion of reconciling reserve assumptions, dilution, operating performance, and investor-facing technical disclosure. Available at https://gosselinmining.com/services/mining-project-evaluation-due-diligence/ (Accessed on 30 March 2026)
  13. Gosselin Mining (online) Mine planning & engineering. Internal service page relevant to the discussion of grade assumptions, dilution control, mining losses, operating reconciliation, and plan-versus-performance review. Available at https://gosselinmining.com/services/mine-planning-engineering/ (Accessed on 30 March 2026)