Chilwa Minerals Doubles Mpyupyu Resource to 109.6 Mt with 89% Measured and Indicated

Resource Upgrade Positions Mpyupyu as Development Focus

Chilwa Minerals Limited (ASX:CHW) has delivered a defining upgrade to its Mpyupyu heavy mineral sands (HMS) deposit at the Chilwa Critical Minerals Project in southern Malawi. The Mineral Resource Estimate (MRE) more than doubled to 109.6 million tonnes, a 114% increase, with approximately 89% now classified in the Measured and Indicated categories. This upgrade significantly boosts geological confidence and underpins Mpyupyu as the company’s first potential development front, with a Scoping Study underway and expected in the third quarter of 2026.

The contained heavy mineral concentrate (HMC) rose by 62% to 3.61 million tonnes, dominated by ilmenite and zircon, Chilwa’s primary HMS products. While the average total heavy mineral (THM) grade fell from 4.36% to 3.28% due to the inclusion of additional lower-grade material, a substantial high-grade core of 50.6 Mt at 4.65% THM remains, offering attractive feed for early mining years.

Sonic Drilling and Advanced Modelling Drive Confidence

The upgrade is underpinned by extensive infill sonic drilling, 1,398 holes totaling over 6,100 metres, combined with XRF assaying and QEMSCAN mineralogical analysis. Sonic drilling’s denser grid converted the bulk of the deposit to higher-confidence Measured and Indicated categories, with only 11% remaining Inferred, mostly on the deposit’s flanks. The block model used 50m by 50m by 0.5m blocks, aligned with selective mining units, and employed industry-standard inverse distance weighting for grade interpolation.

QEMSCAN analysis confirmed the presence of monazite throughout the deposit, introducing rare earth element (REE) by-product potential alongside ilmenite, rutile, and zircon. This adds a strategic dimension to the project, as monazite contains valuable REEs. The deposit’s proximity, about one kilometre, to the Nakombe niobium-REE target on the same contiguous licence offers synergies for shared infrastructure and integrated development.

Geological Setting and Mineralisation Details

Mpyupyu comprises two main mineralised domains: the higher-grade Dune area in the southwest and the Flat area to the northeast. The Dune domain hosts Measured Resources of 12.82 Mt at 5.03% THM (1.0% cut-off), forming the deposit’s high-grade core. The overall resource is reported at multiple THM cut-offs (1.0%, 2.0%, and 3.0%), with grades increasing at higher cut-offs but tonnage decreasing accordingly.

The deposit’s geology reflects paleoshoreline and dune facies within the Lake Chilwa basin, a tectonically influenced rift valley setting. The mineral sands are sourced from surrounding basement gneisses and alkaline intrusives, which contribute ilmenite, zircon, and other heavy minerals. The project area benefits from well-established sampling protocols, quality control, and rigorous data validation.

Strategic Implications and Next Steps

Managing Director Cadell Buss highlighted that the upgrade marks a transition from exploration to potential development, providing a solid foundation for mine planning and the Scoping Study. He emphasised the strategic value of co-locating HMS with critical mineral discoveries such as niobium and REEs, aiming to use HMS cash flow and shared infrastructure to fund and de-risk other programmes.

Chilwa is advancing sonic drilling at the newly identified Mpyupyu West target, where mineralisation extends over approximately 5 km², potentially adding further resource upside. The company also continues to progress metallurgical test work and environmental assessments, mindful that Lake Chilwa is a Ramsar-designated wetland, although the deposits lie outside the protected areas.

The Scoping Study for Mpyupyu, expected in Q3 2026, will be a critical milestone in assessing the economic viability and development pathway. No decision to mine has been made yet, pending further technical, economic, and regulatory evaluations.