Mount Ridley Confirms World’s Largest Scandium Resource at 946Mt in WA
World’s largest publicly reported scandium resource confirmed at Grass Patch
Mount Ridley Mines (ASX: MRD) has upgraded its Grass Patch scandium resource to 946Mt @ 50.1 ppm scandium (76.8 ppm Sc₂O₃), positioning the project as the largest publicly reported JORC (2012) scandium resource globally. The resource sits co-located with the company’s existing gallium and heavy rare earth resources, strengthening the multi-element critical minerals story at Grass Patch. The upgrade was driven by re-assay of historical drill data rather than new drilling, a capital-efficient strategy that extends mineralisation well beyond prior boundaries.
The upgraded resource now contains 47,357 tonnes of contained scandium metal (72,637 tonnes of contained Sc₂O₃), reported at a 25 ppm cut-off. The deposit is located 25km northeast of Esperance, WA, proximal to deepwater port, road, and power infrastructure. Mount Ridley is progressing its wholly owned, patent-pending Selectro™ Process — a potential pathway to recover scandium, heavy rare earth elements, and gallium simultaneously from a single leach circuit. Initial testwork has returned 80% scandium recovery, with further optimisation underway.
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Inside the resource: two blocks along one corridor
The scandium resource comprises two distinct blocks along the same geological corridor within the Grass Patch Complex. Both blocks host co-located gallium and heavy rare earth resources, and mineralisation is shallow, extending from surface to approximately 70m depth across a strike length exceeding 25km. The system remains open at depth and laterally across the project area, with approximately 80% of tenure completely untested.
| Block | Tonnage | Grade (ppm Sc) | Contained Sc Metal (t) | Contained Sc₂O₃ (t) |
|---|---|---|---|---|
| Block 1 | 367.45Mt | 50.3 | 18,475 | 28,337 |
| Block 2 | 578.63Mt | 49.9 | 28,882 | 44,300 |
| Total | 946Mt | 50.1 | 47,357 | 72,637 |
A capital-efficient path to growth
Mount Ridley’s re-assay approach unlocked significant value from the company’s historical drilling database. A total of 3,271 historical drill pulps were re-assayed, returning numerous near-surface scandium intersections that consistently exceeded the existing average resource grades. Many drillholes terminated in mineralisation, confirming that the scandium system remains open in multiple directions. The re-assay program demonstrated that previous analytical work had not fully captured the extent and continuity of scandium mineralisation across Grass Patch, providing a strong technical basis for incorporating substantial additional mineralised volumes into the updated JORC Mineral Resource Estimate.
Why scandium matters
Scandium is one of the world’s most supply-constrained critical minerals, used in aerospace alloys, defence applications, and solid oxide fuel cells. Global primary scandium production remains limited and is insufficient to meet forecast demand, with existing supply supplemented by inventories and secondary sources. Independent industry forecasts project scandium demand to increase materially over the coming decade as commercial adoption accelerates.
Strategic tailwinds for scandium supply are strengthening. In August 2026, the US Department of War committed a US$400 million conditional loan to Sunrise Energy Metals (ASX: SRL) for its Syerston scandium project. This serves as third-party validation of the scandium supply-shortage thesis. That level of government support underscores the global strategic priority attached to developing new, diversified scandium supply outside China.
The Selectro™ Process: a single-circuit recovery pathway
Mount Ridley’s wholly owned, patent-pending Selectro™ Process provides a potential pathway to recover scandium, heavy rare earth elements, and gallium simultaneously from a single leach circuit. Initial testwork conducted by Nagrom Pty Ltd on a 16.8kg homogenised composite prepared from five historical diamond drill holes demonstrated the simultaneous recovery of multiple critical metals from unbeneficiated Grass Patch material through a single hydrometallurgical process.
Selectro™ Test 2 achieved 80% scandium recovery, approximately 77–83% recovery across the principal heavy rare earth elements tested, approximately 70–77% across the principal light rare earth elements tested, and approximately 56% gallium recovery. These results relate to the tested composite only and were generated from approximately 90g dry-weight aliquots taken from the composite. The results are first-pass, laboratory-scale testwork on a limited sample size. They do not represent commercial-scale or project-wide recoveries, but they demonstrate a fundamentally different metallurgical response compared to conventional hydrochloric acid (HCl) leaching.
Allister Caird, Managing Director & CEO
“This significant scandium resource upgrade is a clear signal that we continue to advance the project across multiple fronts in a systematic and accelerated manner. We’ve now established the world’s largest publicly reported JORC compliant scandium resource, at a time when the commodity is under intense focus from governments and industry seeking to secure supply outside China. Holding the largest scandium resource in the world, alongside our proprietary Selectro™ Process, provides a genuine pathway for Mount Ridley to commercialise this resource together with our broader commodity base at Grass Patch.”
The Selectro™ Process is being developed as a single-feed, multi-commodity hydrometallurgical process rather than requiring completely separate leach pathways for rare earth elements, scandium, and gallium. The process incorporates lower-cost reagents and reagent recycling within a closed-loop configuration. The company considers that this has the potential to reduce reagent consumption and environmental impacts relative to conventional HCl-based processing. Further metallurgical optimisation, beneficiation, separation, and larger-scale testwork is required.
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What’s next: pathway to development
Mount Ridley’s near-term objective is to advance the Selectro™ Process toward pilot-scale validation and commercial development. The company has outlined the following forward workplan:
- Selectro™ demonstration plant — Scoping study discussions are underway with multiple reputable engineering firms to inform the design and costing of a planned demonstration plant, which will validate the Selectro™ flowsheet at larger scale.
- Density testwork — Additional density testwork is planned to support upgrading portions of the resource to higher JORC confidence categories.
- Phase 2 re-assay program — The Phase 2 re-assay program is continuing across the Grass Patch Complex, targeting further near-term resource upgrades.
- Institutional engagement — Mount Ridley has executed a Materials Transfer Agreement with Oak Ridge National Laboratory, with ongoing engagement with Lawrence Livermore National Laboratory and Fraunhofer (Germany).
- Flotation and Selectro™ testwork — Flotation testwork is planned to validate TIMA mineralogical findings, with subsequent Selectro™ leach testing to assess recovery improvements on beneficiated ore. Continued Selectro™ testwork on other deposits and metals will evaluate the broader applicability of the underlying chemistry.
Mount Ridley combines the largest publicly reported scandium resource with proprietary processing technology and strong logistics. The project sits 25km northeast of Esperance with proximity to deepwater port, road, and power infrastructure. The company’s tenement package covers approximately 1,000 km², of which approximately 80% remains completely untested for scandium mineralisation. Seven untested gravity target zones extend over a combined ~33km of strike, including targets immediately adjacent to the existing resource areas. This is a genuine multi-element critical minerals development story with significant untested exploration upside.
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