Mount Ridley’s Huge Scandium Resource Raises Questions on Processing and Expansion

• Maiden Inferred Mineral Resource of 367.98Mt at 57.3 ppm scandium
• Resource contains 18,855 tonnes of scandium metal and 28,920 tonnes of scandium oxide
• Co-located with significant gallium and heavy rare earth element mineralisation
• Resource spans three blocks within the Grass Patch Complex with extensive untested targets
• Metallurgical testwork underway to evaluate integrated multi-element processing

A Landmark Scandium Discovery

Mount Ridley Mines Limited (ASX, MRD) has taken a significant step forward in the critical minerals sector with the announcement of its maiden scandium mineral resource estimate at the Mount Ridley Project, located 25 kilometres northeast of Esperance in Western Australia. The Inferred Mineral Resource totals an impressive 367.98 million tonnes at 57.3 parts per million (ppm) scandium, equating to 18,855 tonnes of contained scandium metal and 28,920 tonnes of scandium oxide (Sc2O3). This positions Mount Ridley among the largest publicly reported scandium resources globally.

The resource is distributed across three blocks; 1A, 1B, and 2; within the Grass Patch Complex, a geological corridor known for hosting multi-element critical mineralisation. Notably, the scandium mineralisation is spatially associated with gallium and heavy rare earth elements (HREEs), enhancing the project’s strategic value.

Strategic Multi-Element Potential

The co-location of scandium with gallium and rare earth elements within the same regolith-hosted clay and saprolitic horizons offers a compelling opportunity for integrated mining and processing. This synergy could lead to capital efficiencies and operational simplicity, as the minerals can potentially be extracted through a single processing flowsheet.

Mount Ridley’s CEO, Allister Caird, highlighted the significance of this discovery, noting that the project’s unique geology and critical mineral richness could have global implications. The resource’s proximity to established infrastructure, including the deepwater port at Esperance, further supports its development potential.

Exploration and Metallurgical Advances

The scandium resource was delineated through extensive drilling; 395 holes totaling over 14,000 metres; using aircore and diamond drilling techniques. The mineralisation extends over 15.5 kilometres in strike length and up to 1.5 kilometres in width, with consistent thicknesses suitable for bulk-tonnage open-pit mining.

Metallurgical testwork conducted between 2022 and 2023 demonstrated promising results, particularly with hydrochloric acid leaching achieving up to 85% recovery of magnet rare earth elements, including scandium. These findings underpin ongoing efforts to refine processing pathways that could efficiently recover scandium alongside gallium and rare earths.

Geopolitical and Market Context

Scandium is a rare metal prized for its ability to enhance aluminium alloys used in aerospace, defence, and advanced manufacturing. Global supply is highly concentrated, with approximately 95% of production sourced from China, Russia, and Kazakhstan, raising supply chain security concerns for Western allied nations.

In this context, Mount Ridley’s large-scale scandium resource aligns with strategic initiatives such as the 2025 Australia-United States Framework for Securing Supply of Critical Minerals. The project’s multi-element critical mineral portfolio positions it as a potential key supplier to allied markets seeking to diversify away from geopolitically sensitive sources.

Future Outlook and Growth Potential

Despite the substantial maiden resource, more than 75% of the Mount Ridley tenure remains untested for scandium, gallium, and rare earth elements. The company has identified multiple high-priority gravity and magnetic target zones along a 33-kilometre corridor, which could significantly expand the resource base.

Mount Ridley is advancing resource definition drilling, metallurgical studies, and strategic partnerships with technical experts and allied governments. These efforts aim to unlock the full economic potential of the project and support its evolution into a major multi-element critical minerals operation.

Bottom Line?

Mount Ridley’s maiden scandium resource cements its role in the critical minerals landscape, but metallurgical validation and exploration success will be key to unlocking its full value.

Questions in the middle?

• How will ongoing metallurgical testwork impact the economic viability of scandium recovery?
• What are the timelines and capital requirements for advancing Mount Ridley towards development?
• Can further drilling along the newly identified target corridors significantly increase the scandium and rare earth resource?