Extraction / Mining Mapping
In October 2025, Fortuna Mining published a Preliminary Economic Assessment for the Diamba Sud gold project in Senegal that produced numbers rarely seen in West African gold development. At a gold price of $2,750 per ounce, the PEA shows an after-tax net present value (5%) of $563 million, an after-tax internal rate of return of 72%, and a capital payback period of 0.8 years. Ten months. Initial capital is estimated at $283.2 million. The project would produce 840,000 ounces of gold over an 8.1-year mine life, averaging 106,000 ounces annually. In the first three years, average annual production rises to 147,000 ounces at an all-in sustaining cost of $904 per ounce. Fortuna’s stock hit an all-time high on the announcement. The economics speak for themselves. What they also do is set a benchmark that reshapes how the investment community evaluates gold project returns in the region.
The PEA base case uses $2,750 per ounce. Gold has been trading above $3,000 since early 2026 and approached $5,000 at points in mid-2026. At current prices, the NPV, IRR and payback metrics improve substantially. An AISC of $904 per ounce in the first three years provides a margin exceeding $4,000 per ounce at spot. Even at the life-of-mine average AISC of $1,238 per ounce, the margin remains extraordinary. These are not marginal project economics. They are the kind of numbers that allow a company to fund construction from its own balance sheet, which is exactly what Fortuna is positioned to do: as of Q2 2025, the company reported liquidity of $537.3 million and a net cash position of $214.8 million.
On February 4, 2026, Fortuna submitted an application for an exploitation permit to Senegal’s Ministry of Energy, Petroleum and Mines. The company is simultaneously advancing early works at the site, including camp expansion, site preparation and detailed engineering programmes designed to de-risk critical path activities ahead of the feasibility study. An updated mineral resource estimate was planned for publication by the end of February 2026, forming the basis for the mineral reserves to be used in the feasibility study. The feasibility study itself is targeted for mid-2026. Assuming a positive construction decision, full construction would start in Q4 2026, after the rainy season. First gold pour is targeted for Q2 2028.
The resource base underpinning the PEA consists of 14.2 million indicated tonnes grading 1.59 grams gold per tonne, containing 724,000 ounces, and 6.2 million inferred tonnes grading 1.44 grams for 285,000 ounces. Total contained gold in the mined resource is 932,000 ounces. The deposit sits within the Mako Gold Belt, part of the Kedougou-Kenieba Inlier, a geological domain that hosts world-class deposits including B2Gold’s Fekola mine across the border in Mali. The geological setting is orogenic gold within Birimian greenstone, the same belt that runs through Senegal, Mali, Guinea, Ivory Coast and Ghana and that has produced millions of ounces across the region. Fortuna’s CEO has indicated that continued exploration success could extend Diamba Sud’s mine life beyond a decade. A $17 million budget has been approved to advance early construction works.
The Senegalese context is a factor in how the market is pricing this project. Senegal has emerged as one of the more predictable regulatory environments for gold mining in West Africa. The government holds a 10% free-carried interest in Diamba Sud, with the option to acquire an additional contributory stake of up to 25%. The permitting process, while requiring ESIA approval and an exploitation permit, has advanced on a timeline that market observers describe as delivering predictable regulatory outcomes. This contrasts directly with the situations documented elsewhere in this series: Mali’s provisional administration of Loulo-Gounkoto, Ghana’s proposed sliding royalty regime, and Senegal’s own recent audit and revocation of 71 mining licences under the Sonko administration.
The licence revocation programme is worth examining more closely because it sits in apparent tension with the Diamba Sud permitting timeline. In 2025, the Senegalese government conducted comprehensive audits of the mining sector, revoking 71 licences that were deemed non-compliant or inactive. The programme was framed as an assertion of state oversight and a cleanup of speculative licence holdings. For a project like Diamba Sud, operated by a dual-listed, well-capitalised mid-tier with a defined resource and advancing toward feasibility, the audit environment is not a threat. It is, if anything, a signal that the regulatory framework differentiates between speculative holders and serious developers. For investors evaluating jurisdiction risk, the distinction matters: a government that enforces its mining code is not the same as a government that changes it retroactively.
Diamba Sud would become Fortuna’s second gold mine in Africa, after its Seguela operation in Ivory Coast. The company is building a multi-asset portfolio across the Birimian belt, diversifying production across jurisdictions with different risk profiles. Seguela in Ivory Coast provides operational cash flow. Diamba Sud in Senegal provides the growth pipeline. The two assets are geographically proximate, sit on the same geological belt, and are operated by the same management team, which allows for shared technical and operational expertise.
The broader significance of the Diamba Sud PEA lies in what it says about the current economics of West African gold at elevated prices. A 0.8-year payback on a $283 million capex project is exceptional by global standards, not only by African standards. It reflects a convergence of grade profile (high early-year grades driving front-loaded cash flow), cost structure (AISC under $1,000 per ounce in years 1 to 3), and gold price environment (base case at $2,750 is conservative relative to spot). This convergence is not unique to Diamba Sud. It characterises a range of projects across the Birimian belt where oxide ore, open-pit geometries and moderate capex requirements intersect with a gold price that has nearly doubled in two years.
The article on Desert Gold’s Barani East documented how modular processing is lowering the threshold for small-scale oxide production. Diamba Sud operates at a different scale ($283 million capex, 147,000 ounces per year in early years) but benefits from the same fundamental dynamic: shallow, oxide-accessible gold in West Africa, developed at a moment when the gold price makes the economics of even mid-grade deposits exceptionally attractive. The question that runs through the regional pipeline is the same: which projects can convert these economics into operating mines before the price environment changes, and which will remain studies on paper?
For Diamba Sud, the construction decision targeted for mid-2026 is the inflection point. The PEA economics are established. The permit application is filed. The early works are underway. The balance sheet supports self-funding. What remains is the feasibility study confirmation, the permit grant, and the decision to commit capital to construction. If Fortuna proceeds on the current timeline, Diamba Sud would be Senegal’s fourth industrial-scale gold operation and one of the highest-return gold projects to enter construction in West Africa in recent years.