Chilwa Minerals Ltd (ASX:CHW) has more than doubled the Mineral Resource Estimate for its Mpyupyu heavy mineral sands deposits in southern Malawi to 109.6 million tonnes, positioning the asset as the company’s largest deposit and a potential first development front within the broader Chilwa Critical Minerals Project.
The updated resource, reported at a 1.0% total heavy mineral (THM) cut-off, comprises 24.5 million tonnes in the Measured category, 73.6 million tonnes Indicated and 11.6 million tonnes Inferred, meaning about 89% of the resource is now classified as Measured and Indicated.
Contained heavy mineral concentrate has increased to 3.61 million tonnes from 2.23 million tonnes, while a higher-grade core of 50.6 million tonnes at 4.65% THM has been defined at a 3.0% THM cut-off.
Updated Mpyupyu Mineral Resource Estimate (at 1.0% THM cut-off)
Resource upgrade follows sonic drilling
The updated estimate follows infill sonic drilling, XRF assaying and QEMSCAN mineralogical analysis, with Chilwa saying the work has improved geological confidence and provided a stronger foundation for mine planning and its ongoing Scoping Study.
Average THM grade reduced to 3.28% from 4.36%, reflecting the inclusion of additional lower-grade material, but overall tonnage increased by 114% and contained THM rose by 61%.
Movement in Contained THM (Mt) per resource category for all deposits on the license, 2023 to June 2026. Column segments show the THM grade (%) for each resource category.
Chilwa managing director Cadell Buss said the update represented “a defining step” in the company’s transition from explorer to potential developer.
“In a single update, Mpyupyu has become our largest deposit and the natural starting point for development within the Chilwa Critical Minerals Project,” Buss said.
“No decision to mine has been made, but we now have a deposit we can plan around.”
Critical minerals potential
Mpyupyu forms part of the Chilwa Critical Minerals Project, which contains 10 heavy mineral sands deposits near Lake Chilwa in southern Malawi.
The deposit is also close to Chilwa’s Nakombe niobium-rare earth element target, with the company highlighting the potential for future shared infrastructure across its heavy mineral sands, niobium, rare earth and ionic clay rare earth programs.
Chilwa Minerals Project and HMS deposits outlined to date.
QEMSCAN analysis confirmed monazite throughout the Mpyupyu deposit, giving Chilwa a basis to assess potential rare earth by-product economics alongside its main ilmenite, zircon and rutile products.
The company said sonic drilling was also underway at the newly identified Mpyupyu West target, where heavy mineral sands mineralisation has been mapped over about 5 square kilometres.
Scoping Study due in Q3
Chilwa is progressing a Scoping Study for Mpyupyu, which is expected to be released in the third quarter of 2026.
Any development decision remains subject to completion of the study, further technical and economic assessment, financing and regulatory approvals.
About Chilwa Minerals
Chilwa Minerals is a critical minerals explorer focused on southern Malawi, where it is advancing a portfolio of heavy mineral sands, niobium-rare earth, carbonatite-hosted rare earth and ionic clay rare earth opportunities within a single contiguous licence area.
Its strategy is for heavy mineral sands to be the first program into production, subject to future development studies and approvals, with potential cash flow and infrastructure to support the broader critical minerals portfolio.