Encounter Resources Expands Aileron Niobium Resource by Over 50% to 120 Million Tonnes

Resource Surge Positions Aileron as Major Niobium Contender

Encounter Resources (ASX:ENR) has delivered a substantial upgrade to its Aileron niobium project, announcing a 54% increase in the combined inferred mineral resource estimate (MRE) to 120 million tonnes grading 0.77% Nb2O5. This follows an intensive 2025 drilling program that expanded the Green deposit’s contained niobium by 83%, now sitting at 100Mt at 0.71% Nb2O5, reinforcing Aileron’s status as one of the world’s largest undeveloped niobium deposits.

The scale and grade improvements at Green, the project’s flagship deposit, provide a robust foundation for Encounter’s ambition to develop a long-life, high-grade mining operation. Executive Chairman Will Robinson highlighted the resource growth along strike and at depth, underscoring the potential for a multi-decade mine life supported by strong grades and expanding tonnage.

Pre-Development and Exploration Momentum

With the resource base significantly enlarged, Encounter is pivoting towards pre-development activities, including metallurgy, mining, environmental, geotechnical, and hydrogeological studies. Metallurgical test work is prioritising the Green deposit, focusing on beneficiation and impurity removal to optimise processing flowsheets. Environmental baseline surveys and heritage assessments are underway, with no material impediments reported so far.

Drilling efforts continue to focus on upgrading resource classification, particularly targeting high-grade starter pits through infill drilling planned to commence in May 2026. The current resource remains classified as Inferred, reflecting relatively broad drill spacing, but infill programs aim to reduce uncertainty and improve grade continuity.

Beyond Green, Encounter is advancing exploration across approximately 15 regional prospects within the West Arunta tenure, aiming to expand the niobium and rare earth element (REE) resource base. The company has already identified high-grade REE intersections on the margins of the niobium deposits, indicating potential for separate REE-dominant deposits within the carbonatite complexes.

Geological and Market Context

The Aileron Project sits within the Proterozoic West Arunta Province, a geologically underexplored region hosting carbonatite-related niobium deposits at Green, Emily, and Crean. The mineralisation is oxide-enriched, derived from weathered primary carbonatites, and occurs beneath 20 to 60 metres of cover extending 80 to 180 metres below surface. Encounter’s updated MRE reflects refined geological modelling and variography, with Snowden Optiro preparing the estimate in compliance with the JORC Code (2012).

Niobium is a critical mineral essential for high-strength low-alloy steels, superconductors, aerospace, and emerging battery technologies. Global supply is heavily concentrated in Brazil, with the Araxá mine accounting for over three-quarters of production. Aileron’s grades, ranging between 1.5% and 2.0% Nb2O5 in key deposits, are comparable to world-class benchmarks, positioning the project as a potentially significant new source for the market.

This resource upgrade follows Encounter’s earlier announcement of high-grade niobium and rare earth element intersections at Green, which extended mineralisation over a 4km strike and set the stage for the current MRE expansion. The company’s systematic approach to exploration and development is reflected in its focus on both niobium and REE domains, leveraging the multi-phase nature of the carbonatite intrusions for diverse critical mineral opportunities.

Technical and Operational Considerations

The MRE update is based on over 16,000 metres of drilling at Green in 2025, with a drill spacing of approximately 200m by 80m, locally as close as 40m. Despite improved resolution, the spacing remains broad for detailed grade estimation, prompting planned infill drilling to enhance confidence and resource classification.

Sampling and assay protocols follow industry best practices, with rigorous QAQC and independent verification by Snowden Optiro. Bulk density measurements employ advanced 3D scanning techniques to accurately capture sample volumes, and metallurgical studies indicate favourable liberation characteristics of pyrochlore, the dominant niobium mineral.

Environmental and heritage assessments to date have not identified significant constraints, supporting the potential for future project development pending further studies and regulatory approvals.