Jindalee Lithium (ASX:JLL) strengthens geological and metallurgical confidence at McDermitt through 2025 core drilling

Jindalee Lithium Managing Director and Chief Executive Officer Ian Rodger addresses the outcomes of the 2025 large diameter PQ3 core drilling program at the McDermitt Lithium Project, with a focus on grade continuity, the scale and shallow nature of lithium and magnesium mineralisation, the implications for metallurgical optimisation, and the technical foundations being established for future resource definition and Feasibility level studies.

How do the 2025 PQ3 core drilling results at McDermitt compare with prior reverse circulation drilling in terms of grade continuity and geological confidence?

The 2025 program was designed to validate earlier reverse circulation drilling while also delivering large diameter core for metallurgical and geotechnical purposes, and the comparison between the two datasets has therefore been a central technical objective.

Three of the five PQ3 core holes, R94, R95 and R96, were collared to twin historic RC holes MDRC 24, MDRC 21 and MDRC 22 respectively, enabling a direct, spatially coincident assessment of grade and thickness continuity within the same stratigraphic positions.

The close alignment between the two drilling methods is evident in both grade tenor and intercept thickness, with R94 returning 66.0 m at 1599 ppm Li from 0.4 m compared with 68.6 m at 1131 ppm Li from surface in MDRC 24, R95 intersecting 29.5 m at 1917 ppm Li from 23.0 m against 29.0 m at 1801 ppm Li from 24.4 m in MDRC 21, and R96 recording 20.1 m at 1514 ppm Li from 0.4 m versus 21.4 m at 1590 ppm Li from surface in MDRC 22.

Within this context, the drilling has confirmed that the mineralised horizons display strong vertical consistency.

“The close correlation between core and RC intercepts supports the reliability of the existing geological and grade model and reinforces confidence in the continuity of shallow lithium mineralisation across the deposit.”

This continuity provides a robust technical foundation for subsequent resource definition and engineering studies, while the Company will now progress detailed geostatistical analysis to further quantify the relationship between drilling methods and to determine the most appropriate drilling approach for future infill and resource upgrade programs.

What do the reported lithium and magnesium intercepts indicate regarding the scale and near surface nature of mineralisation within the McDermitt deposit?

All five PQ3 core holes intersected significant lithium and magnesium mineralisation from shallow depths, confirming that the upper portions of the McDermitt deposit host broad, laterally continuous mineralisation commencing close to surface and extending over substantial true thicknesses.

R92 returned multiple mineralised intervals including 36.5 m at 1951 ppm Li and 5.23 % Mg from 24.5 m, while R94 intersected 66.0 m at 1599 ppm Li and 4.12 % Mg from 0.4 m, and R95 delivered 110.6 m at 1519 ppm Li and 4.80 % Mg from 23.0 m, representing one of the thickest continuous intersections drilled at McDermitt.

Given the flat lying lacustrine stratigraphy and the vertical orientation of drilling, the reported downhole widths are representative of true thickness.

“The presence of thick, near surface lithium and magnesium intervals across all holes confirms the scale and tabular geometry of the mineralised system within the Indicated and Inferred Resource domains.”

R93 and R96 further reinforce this interpretation, with multiple zones grading above 1400 ppm Li and magnesium commonly in the range of 4 % to 6 %, demonstrating that both metals are consistently distributed throughout the same shallow stratigraphic package

How will the high quality core samples be utilised to advance metallurgical and process optimisation work?

The selection of PQ3 diameter core, at approximately 8.5 cm, was driven by the requirement to obtain large, intact samples suitable for advanced metallurgical and geotechnical testing.

The core has been systematically logged, photographed and quartered, with representative samples prepared for assaying and retained for comprehensive metallurgical test programs.

Building on the Pre-Feasibility Study, which demonstrated that McDermitt mineralisation can be beneficiated using attrition scrubbing followed by sulphuric acid leaching at moderate temperature and atmospheric pressure to produce battery grade lithium carbonate, the current program enables further refinement of process parameters, variability testing across lithological domains and assessment of impurity deportment.

“The availability of large diameter core allows more representative comminution, leach kinetics and solution chemistry testing, providing engineering level data to support flowsheet optimisation and recovery improvement.”

In parallel, the same core material will be utilised to evaluate processing routes for magnesium, allowing integrated assessment of lithium and potential by product recovery within a single flowsheet framework.

What is the significance of confirming both lithium and magnesium grades in the context of the Company’s value optimisation strategy?

The 2025 drilling has confirmed that magnesium is a pervasive and continuous component of the mineralised system, occurring within the same shallow, laterally extensive horizons that host the lithium mineralisation.

Magnesium grades commonly range between approximately 4 % and 6 %, including 5.23 % in R92, 5.45 % in R93, 4.12 % in R94, 4.80 % in R95 and 5.29 % in R96, demonstrating consistent grade and thickness across multiple holes.

This geological continuity directly underpins the value optimisation program announced in October 2025, which is focused on assessing the potential for magnesium recovery as a by-product alongside lithium carbonate.

“The confirmation that elevated magnesium grades are spatially coincident with the main lithium horizons provides the foundation for evaluating co product recovery and its potential contribution to overall project economics.”

With representative core now available, metallurgical testwork can advance to assess magnesium deportment, recovery pathways and purification requirements within the broader processing flowsheet.

How do the geological and geotechnical data from the 2025 core program contribute to future development and study work at McDermitt?

Beyond assay and metallurgical outcomes, the PQ3 core program has delivered high quality geological and geotechnical datasets that are essential for advancing the project through subsequent study phases.

Core recovery in the zones of interest was typically greater than 95 %, enabling continuous logging of lithology, sedimentary textures, alteration and structural features, as well as the collection of representative samples for density and rock strength testing.

Downhole surveys confirmed that deviations from vertical were generally less than 1°, with a maximum of 1.9°, ensuring confidence in the spatial positioning of geological contacts and grade intervals, while comprehensive photographic and geotechnical logging supports refinement of the geological model within the existing Indicated and Inferred Resource.

“The combination of grade continuity, high core recovery and detailed geotechnical characterisation provides critical input for mine design, slope stability assessment and infrastructure planning as the project advances toward Feasibility level evaluation.”

Advancing McDermitt toward feasibility with strengthened technical foundations

The 2025 large diameter core drilling program has reinforced Jindalee Lithium’s confidence in the continuity, thickness and shallow nature of lithium and magnesium mineralisation at McDermitt, while also delivering the geological, metallurgical and geotechnical datasets required to support the next phase of technical and economic evaluation.

With strong correlation to historic reverse circulation drilling, confirmation of broad mineralised horizons from surface, and the availability of representative core for advanced flowsheet optimisation and potential magnesium co product assessment, the Project is positioned to progress through infill drilling, continued metallurgical refinement and the commencement of Feasibility level studies, underpinned by a strengthened geological model and an expanded understanding of its processing characteristics.

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