4 June 2026

ALTONA RARE EARTHS PLC

("Altona" or "the Company")

REE assay results confirms heavy rare earths enrichment associated to fluorspar

Altona (LSE:REE)(OTCQB:ANRCF), the Africa focused critical minerals exploration and development company, is pleased to announce the receipt of rare earths assay results from its 2025 drilling campaign at Monte Muambe.

Highlights

• ​All rare earths assay results from the 2025 drilling programme are now in hand, and geological modelling of heavy rare earths ("HREE") mineralization associated to fluorspar has started.
• ​Wide significant intercepts have been observed, with up to 30m at 2,677ppm HREO⁽¹⁾, and HREO/TREO⁽²⁾ ratios ranging from 21% to 77%, confirming HREE enrichment is widespread across the Fluorite Zone.
• ​Up to 567ppm dysprosium oxide in individual drilling intercepts.
• ​Xenotime, a HREE mineral, identified for the first time at Monte Muambe, provides a potential pathway to producing a marketable HREE concentrate as a by-product of fluorspar processing.

Received results are from samples from diamond drilling and reverse circulation drilling holes at the Fluorite Zone, Southern Extension, Kudu and Python. All drilling samples were reassayed for rare earths following the identification of HREE enrichment in association to fluorspar announced on 14 April 2026.

Individual dysprosium grades reach up to 567ppm Dy₂O₃, and the significant intercepts weighted average is 172 ppm Dy₂O₃, which is with the usual range for HREE projects.  Dysprosium is a highly sought-after HREE used in a wide range of high technology and defence applications, and the main value driver for this mineralisation. Significant intercepts are listed in the table below.

Mineralogy results from a representative fluorspar ore sample currently undergoing metallurgical testing indicate the presence of xenotime, a HREE mineral reported for the first time at Monte Muambe and absent from the main rare earths resource (which is primarily a neodymium and praseodymium resource). Critically, this suggests that a HREE concentrate could potentially be recovered during fluorspar processing at materially lower incremental cost than a standalone HREE operation, which could significantly enhance the overall fluorspar project economics.

Next steps

Subject to the outcome of ongoing geological modelling, the Company expects to determine in the coming weeks whether a dedicated HREE mineral resource estimate is warranted.

Cedric Simonet, CEO, commented: "These results are highly significant. Widespread HREE enrichment in association with fluorspar, combined with the first identification of xenotime at Monte Muambe, opens a compelling pathway to HREE production as a by-product of our fluorspar operation. If confirmed by ongoing metallurgical work and geological modelling, this would meaningfully enhance the project's value proposition and add a fourth strategic commodity to Monte Muambe's already exceptional multi-commodity profile."

(1)  HREO is the sum of all rare earth elements from samarium to yttrium, expressed as oxide.

(2)  TREO is the sum of all rare earth elements from lanthanum to yttrium, expressed as oxide.

The information contained within this announcement is deemed by the Company to constitute inside information as stipulated 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 virtue of the Market Abuse (Amendment) (EU Exit) Regulations 2019.

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Altona Rare Earths Plc

Louise Adrian, CFO                                                   +44 (0) 7721 492 922 ([email protected])

Strand Hanson (Financial Adviser)                                                      +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 (LSE:REE)(OTCQB:ANRF) is a London Main Market-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 near-term monetisation alongside long-term growth.

The multi-commodity Monte Muambe Project in northwest Mozambique is a highly prospective tenement hosting rare earths, fluorspar, and gallium mineralisation. Published JORC mineral resource estimates include:

·    13.6Mt at 2.42% TREO

·    3.48Mt at 20.6% CaF₂

·    11.73Mt at 54.7g/t Ga₂O₃

The project is held under a 25-year mining licence and has received US Government support in the form of a US$ 1.875 million grant from USTDA to advance the rare earths component through the prefeasibility stage.

Altona's diversified portfolio also includes the Sesana Copper-Silver Project in Botswana, strategically located just 25 km from MMG's Khoemacau Zone 5 copper-silver mine. Situated on a recognised regional contact zone for copper deposits, Sesana represents a compelling exploration opportunity aligned with Altona's growth strategy.

With a unique combination of critical raw materials projects, Altona is well positioned to contribute to the global supply of highly sought commodities essential for clean energy, high technology, defence and industrial applications.

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

Competent Person Statement

The information in this RNS that relates to geology and exploration results is based on information compiled and/or reviewed by Cédric Simonet, who is a Member of European Geologist Federation (Eur. Geol. #739). Cédric Simonet is the Chief Executive Officer and a Director of the Company. He has sufficient experience which is relevant to the styles of mineralisation and type of deposit under consideration and the activity which he is undertaking 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 in the RNS of the matters based on his information in the form and contest in which it appears.