Final assay results confirm high-grade, near-surface fluorspar and gallium mineralization at Monte Muambe

Altona (LSE:REE)Monte, a resource exploration and development company focused on critical raw materials in Africa, is pleased to announce the receipt of all excellent assay results from its 2025 drilling campaign at Muambe.

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• all tests received: Final results of the 2025 drilling program are now in hand, paving the way for the delivery of the Mineral Resource Estimate (“MRE”).
• Record fluorspar intercept: Hole MM156 returned 30 meters from surface at 42.5% CaF₂, representing the highest grade × intercept length ever recorded at the Monte Muambe project.
• Compatible, commercial-grade fluorspar: The weighted average grade of all significant fluorspar intercepts is 30% CaF₂, which aligns with the industry benchmark for commercially viable open-pit mining operations (typically 20-40% CaF₂).
• Gallium results exceed expectations: Gallium mineralization was encountered on continuous intercepts, extending up to 50 m (average 18 m), with a weighted average grade of 63 g/t Ga₂O₃. These results exceeded internal pre-drilling expectations.
• Gallium metallurgy testing underway: A gallium metallurgical test program was launched last week to assess the recovery potential from fluorspar tailings, an essential step towards evaluating commercial feasibility.

The results obtained match the samples from diamond drilling and reverse circulation drilling holes in Fluorite Zone, Southern Extension, Kudu and Python.

It is notable that the 2025 drilling campaign covered only 40% of the surface area of ​​clay gallium and fluorspar anomalies. The remaining 60% has not yet been drilled, leaving significant scope for the identification and definition of new mineralized areas through additional drilling.

Individual sample grades reach 93.11% CAF₂ and up to 149 g/t ga₂hey₃.

Important intercepts for fluorspar and gallium are detailed in the table below.

Fluorspar results meet expectations

The weighted average of fluorspar intercepts reported in this RNS, which covers 2,842 reverse circulation drilling samples, is 30% CAF.₂Confirms geometry suited for open pit mining, with multiple surface or near-surface intercepts. This is consistent with the Company’s pre-drill expectations for this project as well as the grades at which fluorspar is commercially mined, typically 20% to 40% CAF._2.

Results include a record fluorspar intercept (in terms of grade x intercept length) for hole MM156, of 30 meters at 42.5% CAF.₂.

Gallium results exceed expectations

Gallium results show consistent mineralization with grades above 55 g/t Ga.₂hey₃ In wide intervals (up to 50 m, average up to 18 m). The weighted average grade of the Gallum intercepts is 63 g/t Ga.₂hey₃.

Gallium results far exceeded the company’s pre-drilling expectations. Gallium grades extend into the host rock of fluorspar mineralization, meaning that gallium can be recovered not only from fluorspar ore, but also from fluorspar waste. These results underline the importance of the specialized gallium metallurgical testing workflow initiated by the Company, announced on March 19, 2026.

next steps

All assay results have now been incorporated into the project database and work is underway towards the preparation of the MRE. The Company will provide further updates on the results of the gallium metallurgical test program as this work progresses.

CEO Cédric Simonet commented: “These final assay results give us a complete picture of The 2025 resource drilling campaign has confirmed the high-grade nature of fluorspar mineralization at Monte Muambe, in line with our expectations.

“The gallium results, however, show an extraordinary consistency and exceed our expectations. While gallium associated with carbonatites and fluorspar is a new type of deposit, and much work remains to be done to establish its ultimate commercial feasibility, these results clearly strengthen the case for further investment in gallium studies. The start of gallium metallurgical testing announced last week is an essential part of these studies.

“Now with all investigations in hand, we are fully focused on delivering the MRE. This will be the next major milestone in building a comprehensive understanding of the value of Monte Muambe.”

Significant fluorspar inhibition (greater than 18% CAF).₂):

* Hole finished in mineralization, open at depth.

Significant gallium inhibition (more than 54 g/t Ga).₂hey₃):

The information contained in this announcement is considered by the Company to be inside information determined under the Market Abuse Regulation (EU) No 596/2014 as it forms part of United Kingdom domestic law by virtue of the European Union (Withdrawal) Act 2018 as amended by the Market Abuse (Amendment) Regulation 2019.

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Altona Rare Earths PLC

Cédric Simonet, CEO +44 (0) 7778 866 108 (cs@altonare.com)

Lewis Adrian, CFO +44 (0) 7721 492 922 (la@altonare.com)

Strand Hansen (financial advisor) +44 (0) 20 7409 3494

Christopher Raggett

Imogen Ellis

Zeus Capital (Corporate Broker) +44 (0) 20 3829 5000

simon johnson

james hornigold

About Altona Rare Earths PLC

Altona Rare Earths plc (ticker: REE) is a London Main Markets-listed exploration and development company focused on unlocking the value of critical raw materials across Africa. The company is pursuing a diversified strategy, targeting assets with potential for long-term growth as well as near-term monetization.

The multi-commodity Monte Muambe Project in north-western Mozambique is a highly prospective tenement hosting rare earth, fluorspar and gallium mineralisation. Since acquiring the project in June 2021, Altona has drilled over 7,800 metres, provided a first JORC mineral resource estimate of 13.6Mt at 2.42% TREO, obtained a 25-year mining license (granted December 2024), and published a competent person report and scoping study for the rare earth component of the project (October 2023). The company has received a grant of US$1.875 million from USTDA to advance the rare earth project through the prefeasibility phase.

In parallel, Altona is working on a plan to fast-track the development of high-grade fluorspar veins identified on the western and southern margins of Monte Muembe, with a targeted production of 50,000 tonnes of acid-grade fluorspar per year over a minimum 12-year mine life. Acid-grade fluorspar is a key input into a wide range of applications including hydrofluoric acid, lithium battery electrolyte production and nuclear fuel refining, placing Altona in a strong position to supply this critical material.

The discovery of gallium mineralization with grades of up to 550 g/t identified to date adds further value to Monte Muambe. The Company has established that gallium will be concentrated in fluorspar production tailings and its potential recovery as a fluorspar by-product is being assessed.

Altona’s diverse portfolio also includes the Sesana copper-silver project in Botswana, strategically located just 25km from MMG’s Khoemakau Zone 5 copper-silver mine. Located on a recognized regional exposure area to copper deposits, Cesana represents an attractive exploration opportunity in line with Altona’s growth strategy.

With a unique combination of critical raw material projects, Altona is well-positioned to contribute to the global supply of highly sought-after commodities required for clean energy, high technology, defense and industrial applications.

The Company and the Board remain focused on actively identifying and evaluating additional projects that align with our investment profile and strategic objectives, leveraging our extensive network and combined industry experience to uncover attractive opportunities that can drive long-term growth.

details of competent person

The information related to geology and exploration results in this RNS is based on information compiled and/or reviewed by Cédric Simonet, a member of the Federation of European Geologists (European Geol #739). Cédric Simonet is the Chief Executive Officer and Director of the company. He has sufficient experience relevant to the styles of mineralization and types of deposits under consideration and the activity he is carrying out to qualify as a competent person in terms of the 2012 edition of the Australian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves. Cédric Simonet consents to the inclusion of cases in the RNS based on his knowledge, in the form and in which it appears in the competition.

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