Highlights

  • MPYDD007 returned 37.2 metres at 0.29% Nb₂O₅ from 177.8 metres downhole, including 21.3 metres at 0.35% Nb₂O₅, confirming the high-grade porphyry core at Nakombe South for the second time via independent ICP-MS laboratory assay.
  • Laboratory results confirm four co-occurring critical metals — niobium, tantalum, rare earth elements, and gallium — throughout the 211.7-metre drill intercept from surface, establishing Nakombe South as a genuine multi-commodity system rather than a single-element anomaly.
  • A maiden conceptual Exploration Target of 34.1 to 51.2 million tonnes has been defined for the Nakombe alkaline-syenite intrusion, representing the company's first quantified scale estimate for the system, with three diamond rigs now operating on site.

 

 

Chilwa Minerals Limited (ASX:CHW) delivered one of the more technically detailed exploration announcements on the ASX on 15 June 2026, releasing independent ICP-MS laboratory assay results for diamond drill hole MPYDD007 at its Nakombe South discovery within the Lake Chilwa licence in southern Malawi. The results confirm what the company's earlier drill hole MPYDD006 had first indicated: Nakombe South hosts a genuine high-grade niobium porphyry core within a broader alkaline-syenite intrusion that also carries commercially relevant concentrations of tantalum, rare earth elements, and gallium. Despite the quality of the geological data, CHW shares declined 7.14% to A$0.780 on the day — a movement more reflective of the inherently speculative nature of exploration-stage critical minerals stocks than any negative signal in the announcement itself.

MPYDD007: The Geology Behind the Numbers

Drill hole MPYDD007 is the first hole in the Nakombe South programme to be collared and terminate entirely within the alkaline-syenite intrusion, which means the intercepts it delivered represent a genuine representation of the full geological domain rather than a partial cross-section that enters basement gneisses. This matters for geological interpretation: the fact that the hole ends in mineralisation confirms that the system extends beyond the current drilled extent and that the high-grade porphyry core is not a near-surface feature that thins rapidly at depth.

The headline intercept — 37.2 metres at 0.29% Nb₂O₅ from 177.8 metres downhole, including 21.3 metres at 0.35% Nb₂O₅ from 182.6 metres — sits within a broader 50.6-metre interval at 0.19% Nb₂O₅ from 115.5 metres, which itself is contained within the full 211.7-metre hole intercept averaging 0.17% Nb₂O₅ from surface. The grade profile illustrates a classic alkaline intrusive geometry: a broader, lower-grade syenite envelope surrounding a more concentrated, higher-grade porphyry core. Peak grades of 0.44% Nb₂O₅ occur in a 1.95-metre interval at 184.35 to 186.3 metres downhole, alongside 285 ppm tantalum and 47 ppm gallium — the highest concentrations of all three elements recorded in any single interval to date.

Four Commodities, One System: The Multi-Metal Case

The distinguishing characteristic of the Nakombe South discovery relative to many single-element niobium or rare earth projects is the co-occurrence of four independently commercially relevant critical metals within the same mineralised host. In the current geopolitical environment — where supply chain security for critical minerals has become a strategic priority for Western governments — a project that offers natural diversification across multiple in-demand elements carries a different risk and optionality profile than a single-commodity deposit.

Niobium remains the primary economic driver. Nb₂O₅ grades above 0.3% in a primary alkaline intrusion are considered commercially significant in the context of advanced projects such as CMOC's Niobec in Canada and Anglo American's Catalão in Brazil. The comparison drawn by Managing Director Cadell Buss to Globe Metals and Mining's Kanyika project — one of Africa's most advanced niobium projects, also located in Malawi — is geologically apt: both are hosted in alkaline-syenite intrusions with comparable deposit styles, though Chilwa's Nakombe South is at a considerably earlier stage of development.

Tantalum is present throughout the 211.7-metre intercept at an average of 90 ppm, rising to 161 ppm through the high-grade niobium porphyry core. Buss characterised tantalum as a genuine co-product with theoretical value approaching one quarter that of niobium — a statement that, if borne out by metallurgical testwork, would materially improve the project's economics relative to a niobium-only model. Tantalum is used in capacitors for consumer electronics and aerospace applications and is subject to its own supply concentration concerns.

Gallium — with China controlling more than 90% of global supply and having imposed export controls since 2023 — is present at 34 ppm on average across the full intercept, rising to 42 ppm through the high-grade core. While gallium grades need to be assessed in the context of metallurgical recoveries before a definitive economic contribution can be established, its presence as a by-product in a niobium-dominant system adds to the overall strategic appeal of the project in the current political economy of critical minerals.

The rare earth assemblage is weighted toward light rare earth elements, with neodymium and praseodymium (NdPr) — the primary feedstocks for permanent magnets used in electric vehicles and wind turbines — accounting for between 12.8% and 15.5% of the total rare earth basket. The 211.7-metre intercept returned 1,885 ppm TREO from surface, with a higher-grade interval of 2,142 ppm TREO over 50.6 metres from 115.5 metres. While not at the grade levels of the highest-tenor rare earth projects globally, the NdPr proportion and the co-occurrence with niobium create the basis for a multi-stream processing and revenue model that would be evaluated through upcoming metallurgical work.

Thorium and Uranium: An Early Encouraging Signal

One of the practical challenges facing rare earth and niobium projects in alkaline intrusive systems globally is the co-occurrence of radioactive elements, specifically thorium and uranium, which can complicate processing flowsheet design, waste classification, and product saleability. Chilwa's announcement included provisional measurements of thorium and uranium concentrations from MPYDD007 that are relatively encouraging at this stage: thorium averages approximately 20 ppm in the high-grade porphyry core and approximately 41 ppm in the broader syenite host, while uranium averages approximately 53 ppm in the porphyry core and approximately 28 ppm in the syenite.

These levels are described by the company as 'benign' at this stage — a characterisation that will need to be validated through more detailed radiometric and metallurgical assessment as the programme advances. However, the absence of anomalously high thorium or uranium at this early stage is a meaningful positive data point for project development optionality, particularly given that elevated radioactivity has been the primary obstacle to the advancement of several otherwise high-quality rare earth and niobium projects globally.

Maiden Exploration Target: Scale Defined for the First Time

Alongside the assay results, Chilwa defined a maiden conceptual Exploration Target for the Nakombe alkaline-syenite intrusion — the company's first quantified statement of potential system scale. The target encompasses a high-grade niobium porphyry core and a broader REE-enriched syenite domain, with a range of 34.1 to 51.2 million tonnes. This estimate is based on three-dimensional wireframing of the geological interpretation derived from lithological logging, ICP-MS assay data, and measured bulk densities from drilling to date.

It bears emphasis that the Exploration Target is explicitly conceptual in nature under JORC 2012 guidelines. There has been insufficient exploration to estimate a Mineral Resource, and it is uncertain whether further exploration will result in a Mineral Resource estimate. Investors should treat the tonnage range as an indication of the geological scale the company is working with rather than a defined inventory of recoverable material. The path from Exploration Target to Indicated Mineral Resource requires infill drilling at appropriate spacings and the application of rigorous estimation methodology — a programme that Chilwa has outlined in its Phase 2 and Phase 3 drilling plans.

Three Rigs Running: The Pace of Programme Advancement

The most operationally significant aspect of the 15 June 2026 announcement beyond the assay results is the confirmation that a third diamond drill rig is now active on site, directed at the Nakombe North target. With Rig 1 drilling MPYDD017 on the western margin of Nakombe South and Rig 2 drilling MPYDD014 on the eastern flank, the company is simultaneously testing the lateral and depth extensions of Nakombe South while opening up Nakombe North — a separate geophysical anomaly ranked fifth among the 47 targets identified across the Lake Chilwa licence in 2024.

Three remaining holes in Phase 1, plus 11 holes added to Phase 2, are designed to establish the extents of mineralisation at Nakombe South before defining an infill drilling grid for Phase 3 at spacings appropriate to support an Indicated Mineral Resource estimate. Phase 2 and Phase 3 results are expected by Q2 2027. The QEMSCAN mineralogical analysis of drill core composites — which will provide early insight into mineralogy and potential processing pathways — is expected to be completed in Q4 2026.

Strategic Infrastructure Advantage

A factor that distinguishes Nakombe South from many exploration-stage critical minerals projects is its location approximately 500 metres from Chilwa's existing heavy mineral sands (HMS) Mineral Resource deposits at Mpyupyu. Any future development of Nakombe South could leverage roads, power, water, and logistics infrastructure planned for the HMS project — a potential capital cost reduction that becomes more material as the resource definition programme advances toward feasibility-stage studies. The proximity of the Mpyupyu West HMS target, also adjacent to Nakombe, further reinforces the emerging cluster of mineralisation within a relatively compact geographic area.

Share Price Context and Market Interpretation

The 7.14% decline in CHW shares on 15 June 2026 to A$0.780, against a market capitalisation of approximately A$82.3 million, is unlikely to reflect a negative market reading of the geological data. Exploration-stage announcements of this type — detailed, technically dense, and rich in encouraging data points — often experience short-term selling from investors who entered ahead of an anticipated catalyst and are taking profits regardless of the news quality. The fact that Chilwa's assay results confirmed rather than disappointed relative to MPYDD006's earlier intercepts provides no reason to expect fundamental downward re-rating.

The company's path from here runs through the completion of its drilling programme, the delivery of QEMSCAN and metallurgical results, and ultimately the conversion of the Exploration Target into a Mineral Resource. Each of these milestones carries both technical and market significance. At A$82.3 million market capitalisation, the market is pricing Chilwa as an early-stage explorer with a promising but unquantified asset — a characterisation that could change materially as the resource definition programme delivers results through 2026 and into 2027.