World’s Largest Pollucite-Hosted Caesium Pegmatite Mineral Resource Defined at Shaakichiuwaanaan

Press Release

Rigel and Vega confirmed as a major caesium discovery with potential to be a significant supply source for global markets, including the next wave of terrestrial solar technologies

Highlights

• World’s largest pollucite-hosted caesium pegmatite deposit confirmed at the Shaakichiuwaanaan Project, with a maiden Mineral Resource Estimate (“Caesium Zone MRE”) of:
  • Rigel Caesium Zone
    • Indicated: 163,000 t at 10.25% Cs₂O, 1.78% Li₂O, and 646 ppm Ta₂O₅.
  • Vega Caesium Zone
    • Indicated: 530,000 t at 2.61% Cs₂O, 2.23% Li₂O, and 172 ppm Ta₂O₅.
    • Inferred: 1,698,000 t at 2.40% Cs₂O, 1.81% Li₂O, and 245 ppm Ta₂O₅.
  • Total contained caesium content of 5 kt Cs₂O Indicated and 40.8 kt Cs₂O Inferred, highlighting the scale and global significance of the discovery.
• Caesium resources in the Rigel and Vega zones are now included within the CV13 Pegmatite open-pit resource that forms part of the Company’s consolidated MRE for the Project (including both the CV5 and CV13 pegmatites) (“Consolidated MRE”) – that has been updated and restated as follows:
  • Indicated: 108.0 Mt at 1.40% Li₂O, 0.11% Cs₂O, 166 ppm Ta₂O₅, and 66 ppm Ga.
  • Inferred: 33.4 Mt at 1.33% Li₂O, 0.21% Cs₂O, 155 ppm Ta₂O₅, and 65 ppm Ga.
• Caesium is a high-value, rare, and critical mineral which is currently supply constrained with only limited sources supplying the global market[1]. A discovery of this size, grade, and scale has the potential to be a primary source of supply for the global market, including new and potentially growing applications in emerging next generation terrestrial solar panel applications where caesium has been found to play a vital role in significantly improving panel efficiency, stability, and life span.
• The Company has commenced evaluating options (including a scoping metallurgical program to test pollucite recovery using conventional X-ray ore sorting methods) to advance and incorporate the caesium opportunity at CV13 as a potential additional saleable product into the overall economic development of the Project – to follow completion of the lithium-only Feasibility Study on the CV5 Pegmatite.
• The Company remains on track to deliver a maiden Ore Reserve and Feasibility Study for lithium at the CV5 Spodumene Pegmatite in CYQ3-2025.

Darren L. Smith, Executive and Vice President of Exploration for the Company, comments: “At Shaakichiuwaanaan, we have now defined the largest reported occurrence of pollucite in the world – by a significant margin. To find a pollucite-hosted caesium deposit of this scale and grade is exceptionally rare, with only three deposits globally known to have produced this extremely high-value critical and strategic mineral.”

“The pegmatites of the Shaakichiuwaanaan Project continue to demonstrate their unique, world-class nature for hosting abundant and varied critical minerals. With considerable Mineral Resources for lithium, tantalum, gallium, and now caesium defined – and a Feasibility Study for lithium at CV5 on schedule for completion this quarter – the Company is becoming increasingly well-positioned as an emerging critical minerals powerhouse to global markets.”

Ken Brinsden, President, CEO, and Managing Director, comments: “This is another feather in the cap of our technical team, led by Darren, with their hard work resulting in yet another world-class discovery at Shaakichiuwaanaan. What stands out is the sheer scale and grade of this caesium discovery, relative to anything that’s been found before globally.

It’s also a reflection of the extraordinary geology of this deposit, which hosts lithium, tantalum, and now caesium – all high-value critical minerals – at world-class scale. Given the scale, grade, and proximity to the CV5 Pegmatite, the new caesium discovery at Rigel and Vega has already added further substantial value to the Shaakichiuwaanaan Project.”

“What is particularly exciting for investors is that the addressable market for caesium appears to be at a key inflexion point, with its ability to improve the efficiency and stability of next generation terrestrial solar technologies having the potential to drive a massive increase in global demand. Shaakichiuwaanaan stands to play a driving role in the growth of this exciting new market. As we finalize the maiden lithium-only Feasibility Study for the CV5 Pegmatite, we are excited to start work on unlocking the enormous potential of the caesium resource, now outlined to NI 43-101 and JORC standards, for our shareholders,” added Mr. Brinsden.

Patriot Battery Metals Inc. (the “Company” or “Patriot”) (TSX: PMET) (ASX: PMT) (OTCQX: PMETF) (FSE: R9GA) is pleased to announce a maiden Mineral Resource Estimate for caesium (the “Caesium Zone MRE”) at the Rigel and Vega zones at its 100%-owned Shaakichiuwaanaan Property (the “Property” or “Project”) located in the Eeyou Istchee James Bay region of Quebec. The Rigel and Vega zones are hosted within the CV13 Pegmatite, which is located ~3 km west-southwest along geological trend of the CV5 Pegmatite that is accessible year-round by all-season road, and is situated ~13 km south of the all‑weather Trans-Taiga Road and powerline corridor.

The Company has now confirmed that the Shaakichiuwaanaan Project hosts the world’s largest pollucite-hosted caesium pegmatite deposit (Figure 1, Figure 2, Figure 3, Table 2) after declaring a maiden Caesium Zone MRE of:

• Rigel Caesium Zone
  • Indicated: 163,000 t at 25% Cs₂O, 1.78% Li₂O, and 646 ppm Ta₂O₅.
• Vega Caesium Zone
  • Indicated: 530,000 t at 61% Cs₂O, 2.23% Li₂O, and 172 ppm Ta₂O₅.
  • Inferred: 1,698,000 t at 40% Cs₂O, 1.81% Li₂O, and 245 ppm Ta₂O₅.

The Caesium Zone MRE for Rigel and Vega, hosted within the open-pit resource component of the CV13 Pegmatite – which forms part of the Company’s Consolidated MRE for the Project (including both the CV5 and CV13 pegmatites) – has a total contained caesium metal content of 30.5 kt Cs₂O Indicated and 40.8 kt Cs₂O Inferred. The Rigel and Vega zones were interpreted using a 0.50% Cs₂O grade constraint based on mineral processing analogues and mineralogical analysis supporting pollucite as the predominant Cs-bearing mineral present. Coincident with the pollucite-hosted caesium at Rigel and Vega is high-grade lithium and tantalum, present in the host minerals spodumene and tantalite, respectively, which may be co-recovered as separate concentrates.

The footprint of caesium mineralization at Rigel has been traced over a general area of at least 200 m x 100 m and consists of a single, shallow dipping lens at a depth of ~50 m with a true thickness of <2 m to ~6 m. At the Vega Zone, the footprint of the caesium mineralization has been traced over a general area of at least 800 m x 250 m and consists of two proximal flat-lying lenses, at a depth of ~110 m, with a true thickness of <2 m and up to ~10 m and ~6 m, respectively (Figure 1, Figure 9, Figure 10, Figure 21) .

The Consolidated MRE[2], which includes the Rigel and Vega caesium zones, was most recently announced on May 12, 2025; however, that has now been updated and restated herein this announcement with the inclusion of caesium reporting as part of the overall consolidated resources for the CV5 and CV13 pegmatites.

The restatement of the Consolidated MRE also includes a minor adjustment to the tonnage and tantalum grade at the CV13 Pegmatite. The Consolidated MRE is as follows (Table 1).

• Indicated: 108.0 Mt at 1.40% Li₂O, 0.11% Cs₂O, 166 ppm Ta₂O₅, and 66 ppm Ga.
• Inferred: 33.4 Mt at 1.33% Li₂O, 0.21% Cs₂O, 155 ppm Ta₂O₅, and 65 ppm Ga.

About Caesium

Mineral deposits of pollucite-hosted caesium are extremely rare globally and represent the most fractionated component of LCT pegmatite systems, which are effectively the only primary economic source of caesium globally. Economic deposits of caesium pegmatite are typically on a smaller scale of <10 kt to 350 kt in size compared to deposits of lithium pegmatite that typically range in the millions of tonnes in size (<10 Mt and rarely over 100 Mt).

Globally, it is estimated only three (3) primary caesium mines have historically operated and all were pollucite hosted – Tanco (Canada), Bikita (Zimbabwe), and Sinclair (Australia). At Bikita and Sinclair, the pollucite resources are reportedly to have been exhausted in 2018 and 2019, respectively. Tanco is understood to be approaching the end of its mine-life with extraction from existing tailings piles and/or mine remnants being explored. At Sinclair[3], the mine produced 18,629 tonnes of pollucite pegmatite ore grading 8.3% Cs₂O for a contained metal content of 1,551 tonnes Cs₂O. In comparison to the size of the interpreted caesium zones at Vega (~800 m x 250 m) and Rigel (~200 m x 100 m), the primary ore body at Sinclair was relatively small and measured ~60 m long, up to 20 m wide, and up to 10 m thick, and was situated at a depth~40 m from surface.

The market for caesium compounds and metals is largely opaque because it is not publicly traded like copper or gold, but rather through bi-lateral and term contracts. Further, prices vary depending on its contained caesium form, purity and end-product use. Caesium carbonate (Cs₂CO₃≥99%) currently trades at approximately US$120/kg, however in its refined form caesium metal (Cs >99.5%), is a high value commodity comparable to gold and currently trades around US$2,540/oz (or ~US$81 per gram[4]) (excluding VAT, Price Sourcing – Shanghai Metal Markets).

Caesium is currently supply constrained, with only limited sources supplying the global market. A discovery of this size, grade, and scale has the potential to be a primary source of supply for global markets. This includes existing applications for caesium in oil/gas drilling, medical imaging and now new and potentially growing applications in the terrestrial solar panel industry which has the potential to drive a significant increase in global demand. Caesium has been found to play a vital role in significantly improving next generation solar panel efficiency, stability, and life span through the application of perovskite crystal structures.

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