Key Highlights

  • MRE-5 is the fifth consolidated Mineral Resource Estimate for the Shaakichiuwaanaan property in Quebec.
  • The estimate lifts contained caesium and adds a maiden rubidium resource.
  • Caesium formate, a dense drilling fluid, is one use the company highlights.
  • An updated feasibility study for lithium and tantalum at CV5 is scheduled before the end of 2026.

PMET Resources (ASX:PMT) has released the fifth consolidated Mineral Resource Estimate, known as MRE-5, for its Shaakichiuwaanaan property in Quebec, Canada. Although the project is best known for lithium, the headline of the 4 November announcement is caesium.

Contained caesium oxide in the Caesium Zone estimate has risen 55%, from 71,000 tonnes to 110,600 tonnes, with grade up 31% and tonnage up 18%. The Indicated portion stands at 1.844 million tonnes at 4.40% Cs2O for 81,200 tonnes of contained oxide, and the Inferred portion at 981,000 tonnes at 3.00% for 29,400 tonnes. The estimate has an effective date of 10 July 2026.

The caesium sits in three zones within the CV13 pegmatite. Vega holds most of the tonnage, Rigel the highest Indicated grade at 7.34% Cs2O, and the newly estimated Helios zone adds only a small amount. PMET says the result reaffirms Shaakichiuwaanaan as hosting the world's largest pollucite pegmatite resource; pollucite is the mineral from which both caesium and rubidium would be recovered.

Why a niche metal matters

Caesium is a small, opaque market with few suppliers. One key use is caesium formate, a dense Drilling Fluid for high-pressure, high-temperature oil and gas wells. PMET argues that a large North American source could diversify Supply and, subject to further analysis, potentially become a primary global source over the long term.

That is a company view rather than a demonstrated outcome. Caesium trades largely through private contracts. PMET cites an indicative Shanghai Metals Market Price of around US$250 a kilogram for high-purity caesium carbonate, but warns that this should not be treated as a price it could achieve. The company has not quantified how much caesium could be recovered.

Lithium and tantalum continue to grow

MRE-5 also updates the lithium and tantalum estimate across the CV5, CV13 and CV4 pegmatites. Indicated resources total 113.9 million tonnes at 1.43% Li2O and 164 parts per million Ta2O5, containing about 4.03 million tonnes of lithium carbonate equivalent. Inferred resources add 33.8 million tonnes at 1.24% Li2O.

Contained lithium carbonate equivalent rose 5% on the June 2025 estimate. The update includes a maiden Inferred resource of 1.75 million tonnes at 1.24% Li2O at CV4, about 1.5 kilometres east of CV5, and a maiden rubidium estimate at 0.46% Rb2O in the Indicated category.

PMET notes that 87.4 million tonnes of Indicated material sits in a single principal dyke at CV5, nearly five kilometres long with true widths of up to around 125 metres. The company expects this to reduce dilution and simplify mining.

A sensitivity analysis at a 1.5% Li2O cut-off outlines higher-grade subsets, mainly in the Nova zone at CV5 and the Vega zone at CV13, including 36.5 million tonnes at 2.04% Li2O in the Indicated category. PMET stresses that these figures illustrate sensitivity to cut-off grade and are not a separate Mineral Resource. They nevertheless indicate where early Mining could concentrate if studies support it.

What it does not change

MRE-5 does not materially change the current Mineral Reserve or the findings of the CV5 lithium-only feasibility study announced in October 2025. Resources are not reserves and do not have demonstrated economic viability, and no Measured material is reported.

The year-end milestones

Two studies are scheduled before the end of 2026: an updated feasibility study for lithium and tantalum at CV5, which MRE-5 is intended to support, and a Preliminary Economic Assessment covering lithium, caesium and tantalum across CV5 and CV13. The latter is expected to provide the first economic evaluation of caesium for the project.

A further resource update incorporating 2026 drilling, being carried out with seven rigs, is anticipated in 2027. For investors, the assessment will be the first real test of whether caesium can add value rather than simply tonnes.