The Rio Tinto Exit Unlocks Value : Investors Shift into Aterian’s Critical Metals Story

• 08.12.25

• Source: Total Market Solutions

The Rio Tinto Exit Unlocks Value : Investors Shift into Aterian’s Critical Metals Story

“…being the only London-listed company with an operations and trading presence in Rwanda – ATN offers exposure to both discovery upside and immediate revenue opportunities…”

Exploration, development and trading company Aterian (LON:ATN) is well positioned to rapidly build its mineral trading operations in Rwanda after taking full control of the highly prospective critical metals HCK Project, opening the prospect of building on extensive early investment by Rio Tinto.

With a combination of exploration expertise and trading capability – and the only London-listed company with an operations and trading presence in Rwanda – ATN offers exposure to both discovery upside and immediate revenue opportunities. The company holds critical metal projects in Morocco and Botswana as well as Rwanda.

Taking full control of the HCK Project

ATN’s 70pc owned HCK Project covers 2,750 hectares prospective for lithium, tantalum and niobium, metals in high demand for the renewable energy, automotive, and electronic manufacturing sectors.

Lithium is well known for its use in the batteries that power electronic devices and electric vehicles. Tantalum is primarily used for electronic components in smartphones, laptops, gaming consoles, medical devices and aerospace technology, and niobium for steel alloys, superconductors and specialised electronics. Tantalum and niobium are often found together in the columbite-tantalite ore coltan.

The HCK Project’s prospectivity was sharply defined in the course of ATN’s Joint Venture (JV) agreement with Rio Tinto, which gave the major the right to earn up to a 75pc interest in the project through a $7.5m exploration programme.

Extensive geochemical and geophysical groundwork in 2024 paved the way for drilling this year, with highly positive results published in July encouraging Rio Tinto to exercise its Stage 1 earn-in rights under the JV Agreement and take a 51pc interest. The findings included multiple pegmatite intersections with downhole thicknesses up to 79.44 metres and notable assay results including 6.90 metres from 174.60 metres grading 2.11pc Li₂O (lithium oxide), which contained a higher-grade interval of 3.45 metres at 3.20pc Li₂O from 174.60 to 178.05 metres.

ATN CEO Simon Rollason said: ‘This drill phase is considered scout or reconnaissance in its level of detail, testing only a limited strike length, but indicates that spodumene-bearing pegmatite occurs on the project. Good thickness of pegmatite is observed in several intersections at HCK-1, and when fresh spodumene-bearing pegmatite was intersected, the lithium grade is highly encouraging.’

Late last month Rio Tinto concluded the region did not have ‘the potential scale to support a lithium resource as required by a Tier-1 mining company’, opening the opportunity for ATN to develop the project on its own terms. During the JV Rio committed $4.73m to the project, completing multiple programmes of surface mapping, geochemical sampling, ground-based geophysics and diamond drilling. But significant tantalum, niobium and lithium mineralisation potential remains untested: only two of the twelve defined prospect areas have so far been drilled.

ATN Chairman Charles Bray said: ‘The return of ownership of HCK marks an opportunity for Aterian to unlock value on our own terms especially through dedicated tantalum and niobium mining. Rio Tinto’s exploration programme provides a springboard to assess and develop the tantalum-niobium potential within the licence area. These metals are essential to advanced electronics, aerospace, and energy-storage applications … Building on this significant technical base, Aterian will also continue to evaluate the lithium potential identified within the Project while reassessing the tantalum-niobium opportunity within the same licence area. We view this as a value-creation moment for Aterian and a clear demonstration of our strategy in action-transforming exploration assets into near-term development opportunities that support Rwanda’s formal, conflict-free mineral supply chain.’

ATN will now integrate the exploration dataset and drilling results inherited from Rio into its own regional datasets to fast-track mineral target generation and prioritisation. Exploration will advance with a renewed focus on tantalum, niobium and associated by-products.

Building a vertically integrated exploration and trading platform

ATN now has complete freedom to integrate continued exploration at HCK with its Rwandan mineral trading operations as the company seeks to build a vertically integrated exploration and trading platform for critical minerals across East Africa.

ATN has a metal concentrates off-take agreement with an international metals and minerals trading house allowing for the sale and distribution of tantalum-niobium and tin concentrate secured from Rwandan-based artisanal and small-scale mining companies and cooperatives. All mineral supplies handled by ATN are sourced in accordance with the International Tin Supply Chain Initiative and comply fully with the OECD Due Diligence Guidance.

The agreement opens the company to a $4.5m operational trading facility offering immediate access to capital for scaling up its mineral sourcing and trading volumes across Rwanda and the broader region, facilitating its objective of covering operational expenditures through trading cash flows.

ATN executed its first sales of tantalum-niobium (coltan) concentrates in September, and has opened further channels for supporting its trading operations, including a $250,000 mezzanine loan facility (a hybrid form of business financing that blends debt and equity) and a £455,000 placing.

Moving ahead in Morocco

While building out its Rwandan exploration and trading operations ATN has forged ahead with the development of its other projects. The company has a second interest in Rwanda through its 100pc owned Musasa Project, which targets commodities including lithium, tantalum, niobium, tin and tungsten. Datasets are under examination and primary targets being defined.

Beyond Rwanda ATN has a portfolio of copper-silver, gold and base metal projects in Morocco concentrated within the Anti-Atlas region, known since ancient times for its significant copper deposits.

The Agdz Project, covering 34.46 km2, lies approximately 14 km southwest of the Bou Skour copper-silver mine, with the world-class Imiter silver mine 80 km to the northeast. The five primary prospects have returned grades of up to 26.5pc Cu (copper), 448 g/t Ag (silver) and 3.74 g/t Au (gold). A scout drilling programme has demonstrated mineralisation across the target areas, reporting near-surface copper and silver from three prospects including a three metre interval containing 1.24pc Cu and 101 g/t Ag.

Work at the Tata Project covering 138.6 km2 some 30 km south of the Azrar copper-silver project has indicated the presence of stratiform sedimentary copper along a strike length of 18 km. Exploration results from rock chip sampling have reported up to 7.02pc Cu. Additional discoveries include copper mineralisation over apparent thicknesses of up to 8.5 and 6 metres in the south and north of the project, respectively.

The Azrar Project, comprising an area of 76.9 km2, is located 45 km southeast of the Tizert copper mine. Fieldwork has identified high-grade copper and silver from multiple locations, including 3.79pc Cu and 23 g/t Ag from a fault-related breccia cutting across the project’s central area. Additional copper, silver, and gold mineralisation has been discovered at priority targets, including 0.82 g/t Au and 0.63pc Cu over 9 metres from surface chip channel targeting northerly strike quartz veins. The Jebilet Est Project, covering 73.6 km^2^, has yielded copper grades, including 4.43pc and 3.11pc, with an extensive vein system mapped in the western project area.

This summer ATN signed a pioneering MoU with a machine learning start-up spun out from the University of Cambridge to apply advanced computational modelling to a multi-phase mineral exploration programme in Morocco.

Phase 1 of the pilot will use historical exploration data to develop and back-test a machine learning model designed to identify promising drill targets, aiming to achieve a significant reduction in drilling requirements while maintaining or improving resource estimation confidence. Phase 2, subject to the successful completion of Phase 1 and agreement on commercial terms, will adapt the model to planned future exploration across ATN’s portfolio of pipeline projects, delivering significant cost savings and accelerating discovery timelines.

Mr Bray said: ‘Harnessing the power of AI to analyse and interpret complex geological data in ways never before possible opens an entirely new chapter in how we explore and discover mineral resources.’

Prospects in Botswana

ATN is also developing prospecting licences in Botswana held by virtue of a 90pc interest in Atlantis Metals. The licences cover some 4,851 km2 across the Kalahari Copperbelt and the Makgadikgadi Pans region, prospective for copper-silver and lithium brine respectively.

Kalahari is one of the world’s most prospective areas for as yet undiscovered sediment-hosted copper deposits, hosting copper deposits and several large stratabound, sediment-hosted copper-silver deposits. Makgadikgadi has been assigned Lithium Zone status by the Botswana government.

Exploration projects that have recently advanced to late-stage development and production within the district include the Khoemacau copper project (MMG – combined mineral resource of 450 million tonnes @ 1.4pc Cu (copper) and 18 g/t Ag (silver)), and the Motheo Deposit and nearby A1 and A4 copper projects (Sandfire Resources – combined mineral resource of 64.1 million tonnes @ 1.0pc Cu and 13.8 g/t Ag).

ATN increased its Botswana licences to 10 this summer with three new Kalahari interests. Preliminary desktop review of available geophysical data has already indicated opportunities for further exploration and assessment of two of the three licences. Licence PL 199/2025 has strong prospective features given it overlies an interpreted plunging antiformal axis with a coincident historical copper-in-soil anomaly covering 4 km^2^. Licence PL 197/2025 highlights the target D’Kar/Ngwako formational contact, which has a combined horizontal distance of 10.5 km, with a historical copper-in-soil anomaly occurring on the western border of the licence.

Outlook

ATN is positioned to take advantage of ever more urgent demand for copper, lithium, tantalum and other critical metals.

Last month the Pentagon sought to procure up to $1bn worth of critical minerals to bolster America’s national stockpile to counter Chinese dominance of metals so essential for defence manufacturers. China has imposed export restrictions on many rare earths in response to tariffs. The US plans to buy up $100m of tantalum, $500mn of cobalt, up to $245mn of antimony and a combined $45mn of scandium.

The US and Australia have acknowledged the importance of maintaining sovereign processing capacity by signing the US-Australia Critical Minerals and Rare Earths Framework. And Europe is moving to secure industrial competitiveness and security by developing its capacity to smelt and refine critical minerals, not just import them.

ATN enters 2026 well placed to pursue its dual mission of moving its exploration assets towards commercialisation and scaling its mineral trading for sustainable profitability. Significant progress has been made this year to establish revenue-generating mineral trading operations in Rwanda and to define the potential of its assets in Morocco and Botswana. Rio Tinto’s exit has given it full control of the exploration of the HCK Project.

Since declaring a cash position of approximately £120,000 to the end of June, ATN has strengthened its financial position through strategic partnerships and funding initiatives.

The company’s share price has risen some 5pc to 38p over the past month, taking ATN’s market cap to £6m, signalling investor recognition of the opportunities opened by the closing of the Rio JV.