Mount Ridley Mines’ first TIMA automated mineralogy study at Grass Patch reveals rare earth elements are locked in discrete phosphate minerals, supporting flotation as a key beneficiation step ahead of leaching and Phase 1 metallurgical testwork.
- Rare earths hosted in xenotime, crandallite, monazite/rhabdophane phosphates
- Phosphates occur within shallow regolith, amenable to flotation concentration
- Flotation testwork fast-tracked to reduce material volume for processing
- JORC-compliant resource estimates confirm significant gallium, scandium, and rare earth oxide tonnages
- Results provide critical input for developing processing flowsheet options
TIMA Study Identifies Rare Earth Mineral Hosts at Grass Patch
Mount Ridley Mines Ltd (ASX:MRD) has taken a significant step forward in understanding its Grass Patch rare earth deposit with results from the first TESCAN Integrated Mineral Analyzer (TIMA) study. The automated mineralogy analysis confirms that rare earth elements (REEs) at Grass Patch are almost entirely hosted within three discrete phosphate minerals: xenotime, crandallite group phosphates, and monazite/rhabdophane. This mineralogical insight is crucial because it directly influences the processing strategy for the deposit.
Unlike ionic clay deposits where REEs are loosely adsorbed on clay surfaces and typically extracted by simple salt leaching, the presence of discrete phosphate minerals opens the door to physical concentration techniques such as flotation. This could allow Mount Ridley to concentrate rare earths before leaching, potentially reducing the volume of material needing chemical processing during its Phase 1 metallurgical testwork.
Phosphates Situated in Shallow Regolith Profile
The TIMA analysis reveals these phosphate minerals are fine-grained and closely associated with clay in the shallow, weathered regolith profile characteristic of Grass Patch. Xenotime, noted for hosting valuable heavy rare earths (HREEs), was the most prevalent phosphate mineral identified. This mineralogical setting supports flotation as a promising beneficiation technique to produce a higher-grade concentrate, which the company is now fast-tracking through bench-scale testwork.
Mount Ridley’s Managing Director Allister Caird highlighted the significance of these findings, noting that peers with comparable regolith-hosted HREE deposits have achieved excellent results applying flotation. He emphasised that flotation could provide optionality in managing the extraction phase and will integrate closely with ongoing Phase 1 metallurgical testwork outcomes.
Robust Resource Base Underpins Processing Plans
Grass Patch’s resource base remains substantial, with JORC-compliant estimates including 838.7 million tonnes at 29.3 ppm gallium, 367.9 million tonnes at 57.3 ppm scandium, and 122.5 million tonnes at 889 ppm total rare earth oxides (TREO). The presence of 44,610 tonnes of heavy rare earth oxides further enhances the project's strategic value. These figures underscore the importance of efficient beneficiation and processing strategies to unlock value from this large-scale deposit.
The company’s approach reflects a broader strategy to develop both upstream exploration and downstream processing capabilities, positioning Mount Ridley as an emerging player in critical minerals supply chains.
Next Steps Focus on Flotation Testwork and Metallurgical Integration
Following the TIMA results, Mount Ridley is advancing bench-scale flotation testwork across various grind sizes to evaluate achievable concentrate grades and recoveries. This work will inform the beneficiation flowsheet ahead of further metallurgical testwork planned for the Grass Patch Project. The flotation pathway could materially impact the economics and operational design of the project by reducing the mass of material requiring leaching.
While no new drilling or resource upgrades are reported in this announcement, the company continues to assess multiple high-priority drill targets identified through historical data and geophysical surveys, with plans for further drilling in 2026. The integration of mineralogical data with metallurgical and resource models will be key to refining project development plans.
Bottom Line?
Mount Ridley’s mineralogical breakthrough at Grass Patch sets the stage for flotation to play a pivotal role in rare earth extraction, but the success of this pathway hinges on upcoming bench-scale testwork results.
Questions in the middle?
- How effectively will flotation concentrate rare earth phosphates in practice at Grass Patch?
- What impact will flotation have on the overall processing costs and project economics?
- Will upcoming drilling and assay results support resource upgrades or extensions in 2026?