Terrain Minerals Confirms 83% Rare Earth Recovery at Larin’s Lane
Key Takeaways
- Curtin University's C3MET Research Group confirmed total REE recovery of 83% using 3 M methanesulphonic acid at 50°C, rising to up to 99% with calcination pre-treatment at 600°C.
- Scandium recovery reached approximately 67–79% under elevated-temperature and calcined conditions, confirming it as a recoverable credit rather than a trace byproduct.
- Gallium recovery jumped from 12–25% under mild conditions to up to 89% with thermal pre-treatment and 3 M MSA at 80°C, though head grades of 20–24 ppm mean economic viability requires further optimisation.
- MSA's biodegradability and absence of chlorine off-gases position Larin's Lane for a potentially lower-impact processing route compared to HCl-based peer projects, which could support future permitting and partner discussions.
- The 9 km × 3 km interpreted mineralisation footprint remains open in all directions with no Mineral Resource Estimate yet defined — the project is at Exploration Target stage under JORC 2012.
Larin’s Lane metallurgical results confirm high rare-earth recovery with scandium and gallium upside
Terrain Minerals (ASX: TMX) has reached a first-stage technical milestone at its 100%-owned Larin’s Lane Prospect, part of the Smokebush Project located approximately 350 km north of Perth, Western Australia. Leaching test work conducted by Curtin University’s C3MET Research Group under MRIWA Research Project M10528 returned a total REE recovery of 83% using 3 M methanesulphonic acid (MSA) at 50°C, rising to up to 99% with thermal pre-treatment (calcination). The results also confirmed scandium as a recoverable credit and identified gallium as a potential additional product stream subject to further study. These are bench-scale results; no assumptions should be made as to the economic viability of recovery at this stage.
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What Curtin University’s leaching test work revealed
Two representative composite samples (D1 and D2) from Larin’s Lane air core drilling were submitted to Curtin University’s C3MET for leaching tests across a range of reagents, acid strengths, temperatures, solid-to-liquid ratios, and durations.
The headline recovery outcomes from the test work were:
- Total REE recovery: 83% (3 M MSA, 50°C, 1 wt% solid-to-liquid, 24 h) — rising to up to 99% with thermal pre-treatment (calcination at 600°C prior to leaching at 80°C)
- Scandium: approximately 46% recovery under mild conditions, rising to approximately 67–79% under elevated-temperature and calcined conditions
- Gallium: approximately 12–25% under mild conditions, improving to up to 89% with thermal pre-treatment combined with 3 M MSA at 80°C (note: head Ga grades in the samples tested are modest at 20–24 ppm; economic recovery remains subject to significant further optimisation and study)
- Ammonium sulphate: less than 2% REE recovery, confirming the mineralisation is not ion-exchangeable and requires an acid-based leaching approach
The table below summarises best-case recovery by leach condition for Sample D1 at 24 hours, reproduced directly from the source announcement.
| Condition (Sample D1) | REE | Sc | Ga | Gangue (Al/Fe) |
|---|---|---|---|---|
| 3M MSA, 50°C, 1 wt%, 24 h | 83% | 52% | 12% | Low |
| 3M MSA, 80°C, 1 wt% | 86% | 68% | 29% (37% after 48 h) | Elevated |
| 3M MSA, 80°C, 1 wt% + thermal pre-treatment | 99% | 79% | 89% | High |
| 3M ammonium sulphate, 50°C, 1 wt% | <2% | 7% | Below detection limit | Low |
REE recovery is largely uniform across the REE suite, with the highest recoveries (greater than 80%) noted for the middle REEs at approximately Nd–Ho. Diagram 1 in the source announcement presents individual element recovery figures as a bar chart; readers are directed to the original ASX announcement for the visual representation.
Why MSA matters — a lower-impact processing route
Methanesulphonic acid (MSA) is a strong organic acid that outperformed the citric and tartaric organic acids also assessed in this test work. For investors unfamiliar with the chemistry, MSA is commercially mature and available off-the-shelf from major industrial suppliers, including BASF, where it is sold under the Lutropur® brand.
What makes MSA particularly relevant here is how it compares to hydrochloric acid (HCl), the reagent on which many peer clay-hosted REE recoveries are reported. Unlike HCl, MSA is readily biodegradable, non-oxidising, and breaks down within the natural sulfur cycle. It does not generate the chlorine-bearing off-gases associated with HCl leaching, pointing to a potentially lower-impact and lower-hazard processing route.
A further encouraging finding is that increasing the pulp density (adding more clay to the reactor while maintaining the same lixiviant volume) did not result in a noticeable reduction in recovery. This suggests acid consumption per tonne of clay treated could potentially be reduced by operating at higher pulp density without material loss in recovery, a variable worth testing further. Recovery is driven primarily by acid strength rather than acid quantity, though higher recoveries were accompanied by increased co-dissolution of gangue elements (aluminium and iron), meaning future optimisation will need to balance REE extraction against reagent consumption and gangue dissolution.
For investors, a potentially lower-impact, lower-hazard processing route could support future permitting processes and partner discussions.
Justin Virgin, Executive Director, Terrain Minerals
“This test work gives Terrain a genuine technical foundation to advance the Project towards resource and scoping-level studies, and to progress discussions with potential partners.”
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What comes next for Larin’s Lane
With rare earth and scandium recovery confirmed at bench scale, Terrain has outlined the following forward program:
- Optimisation test work to define the preferred leaching agents and leach conditions, balancing REE and scandium recovery against reagent consumption and gangue co-dissolution
- Further evaluation of the recoverable scandium credit, and of gallium recovery and head grade
- Integration of metallurgical recovery assumptions into future Mineral Resource and scoping-level studies for Larin’s Lane
- Continued progression of any discussions with potential partners in relation to the critical mineral mineralisation at Larin’s Lane
Larin’s Lane sits within Terrain’s 100%-owned Smokebush Project in the Yalgoo Mineral Field. The same tenement package also hosts the Lightning Gold Prospect, for which a maiden Mineral Resource Estimate (MRE) was released on 27 July 2026, representing the flagship focus of the company’s portfolio. Larin’s Lane represents the critical minerals optionality within that same project.
In terms of scale, maiden air core drilling conducted in late 2023 intersected clay-hosted REE and gallium mineralisation over an interpreted strike of approximately 9 km × 3 km, which remains open horizontally in all directions. The Company released an Exploration Target for the project, reported in accordance with the JORC Code (2012), in November 2024. Note that an Exploration Target is a JORC-defined term distinct from a Mineral Resource Estimate; no Mineral Resource exists for Larin’s Lane at this time.
The MRIWA M10528 research program was co-funded by the Western Australian Government, the Curtin University Resources Technology and Critical Minerals (RTCM) Trailblazer program, and industry co-sponsors, underscoring the external scientific validation attached to this work.
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