Chilwa Minerals Confirms Consistent Geology at Mpyupyu West
Key Takeaways
- Chilwa has drilled 218 of 272 planned Phase I holes (80%) at Mpyupyu West, with completion expected in mid-October 2026.
- Saprolite makes up 63% of the profile, averaging 6.2 m within an 8.6 m mineralised interval, and it is free-dig material.
- No assays are reported, so Mpyupyu West has no grade, tonnage, resource or Exploration Target yet.
- Sink-float assay results due in late October are the next catalyst, followed by a maiden JORC Exploration Target.
- The 17 km² target is larger than the Mpyupyu Dune and Flat deposits combined, and a Scoping Study on the Lake Chilwa HMS deposits is expected in Q4 2026.
Mpyupyu West drilling hits 80% complete as 17 km² outline confirmed
In its 9 October 2026 drilling update, Chilwa Minerals (ASX:CHW, NASDAQ:CHWM) reported that 218 of 272 planned Phase I holes (80%) had been completed at Mpyupyu West. The holes sit on a 400 mN x 200 mE grid across a target area of over 17 km².
Heavy minerals were confirmed by logging and panning of drill core in sand and saprolite units. No assay results are reported, so this is a progress update on the geology, not a grade announcement.
The target covers a larger area than the combined Mpyupyu Dune and Flat deposits. It adjoins the Mpyupyu Mineral Resource of 109.6 Mt at 3.28% THM (1% THM cut-off), though that resource is separate. Mpyupyu West itself has no resource or Exploration Target yet.
Cadell Buss, Managing Director
“…the free-dig saprolite profile has held from near-surface to saprock, at an average depth of around 8.6 metres, hole after hole. Scale and consistency together are what set this prospect apart.”
For investors, a consistent profile across the whole grid matters. It suggests the geology is behaving predictably, which is what a company needs to see before attempting a maiden resource estimate.
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Consistent free-dig saprolite profile from surface
Saprolite is rock that has weathered deeply into a soft, clay-rich material. “Free-dig” means it can be dug without blasting. Drilling intersected the same sequence of sand, silty sand, sandy clay and saprolite, terminating at saprock, a harder, rockier unit.
What the drilling shows
Table 1 in the announcement shows average unit thicknesses from lithological logging supported by panning and pXRF (portable X-ray fluorescence, a handheld chemical analysis tool). Thicknesses were averaged over the lateral extent of the deposit.
| Unit | Avg Thickness (m) | % of Deposit |
|---|---|---|
| Silty Sand | 0.9 | 9% |
| Laterised Silty Sand | 1.6 | 16% |
| Sandy Clay | 1.2 | 12% |
| Saprolite | 6.2 | 63% |
Saprolite makes up the bulk of the profile. Other key observations from the drilling include:
- The average depth to the base of the mineralised interval is 8.6 m, with a maximum of 19.5 m.
- Holes routinely terminate at saprock, which is not amenable to conventional mineral sands mining and processing.
- Some holes were terminated by bit refusal before reaching saprock.
- The profile is deeper in holes south of the Nakombe River.
The company said hole depths will be reviewed as geological modelling progresses.
Why in-situ saprolite matters
“In-situ” means the minerals formed and remain in place rather than being moved. The announcement states that 63% of the mineralisation is hosted in deeply weathered saprolite, rather than in transported aeolian (wind-blown) and strandline sands.
In this style, resistant heavy minerals are residually concentrated in place as less stable minerals break down and are removed. That produces a near-surface blanket that tends to be laterally extensive and predictable.
This contrasts with the transported sands that host Mpyupyu Dune and Flat. The company noted that other deposits of this type have been developed in Malawi, including the Kasiya rutile project in central Malawi. That is a comparison of deposit style only, and no grade or economic comparison is made.
For you as an investor, free-dig, near-surface material points to a simpler deposit style. Whether it proves economic depends on assay results still to come.
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Next steps: assays, Phase II and Scoping Study
The company outlined the following programme:
- Phase I drilling continues with both sonic rigs at about eight holes per day, with completion of the 272-hole programme expected in mid-October 2026.
- The first two sample batches have been shipped internationally for sink-float assay (a lab test that measures total heavy mineral content). Results are expected in late-October, after which the company expects to report a maiden Exploration Target as defined in JORC.
- A Phase II resource-definition grid at a nominal 100 mN x 100 mE spacing is to be designed on completion of Phase I.
- QEMSCAN analysis (which characterises the mineral assemblage) and bulk density studies on the saprolite horizon are planned.
- The Scoping Study covering the HMS deposits on the southern, western and northern shores of Lake Chilwa is advancing and is expected in the fourth quarter of 2026.
Phase I is aimed at achieving an inferred category resource, with infill drilling to a density sufficient for indicated category.
Subject to grant of the adjoining exploration licence application to the west, extensional drilling is planned to test the continuation of the mineralised horizon. Resource-definition drilling at the Bimbi Main deposit will resume on completion of Phase I.
The next key catalyst is the late-October sink-float assay results. Until then, the announcement reports no heavy mineral grade or tonnage for Mpyupyu West, and none should be assumed.
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