Mount Ridley unveils major heavy rare earth prize in WA

Mount Ridley Mines appears to be assembling an intriguing critical minerals combo in Western Australia’s southeast, after chalking up a major heavy rare earths mineral resource estimate at its namesake project, 55 kilometres northeast of Esperance.

The new inferred resource has weighed in at an impressive 122.56 million tonnes grading 889 parts per million (ppm) total rare earth oxides (TREO), hosting 108,954 tonnes of contained TREO. Notably, 44,610 tonnes of that sits in the heavy rare earth (HREO) basket, giving the resource a head-turning 41 per cent heavy rare earth oxides ratio.

The company says the estimate is rich in the magnet metals dysprosium and terbium, with 4,272 tonnes of dysprosium oxide and 719 tonnes of terbium oxide.

Terbium and dysprosium, along with the less well-known rare earths metal samarium, are used in the manufacture of powerful high-temperature resistant permanent magnets, such as those used in electric motors - especially for electric vehicles - and in wind turbines for power generation.

The resource is split between a central zone, Block 1, with 35.36 million tonnes at 746ppm TREO and a northern zone, Block 2, with 87.18 million tonnes at 947ppm TREO.

Adding a neat kicker to the story, the Mt Ridley rare earths appear to sit in the same regolith clay horizons the company has already been mapping out for its other scandium and gallium metals.

Management believes that useful co-location could give Mount Ridley some future optionality with processing, material handling and mining schedules as it figures which metal, or perhaps a combination of which metals, could offer the clearest path to value.

The delivery of a JORC Inferred REE mineral resource of 122.54Mt at 889 ppm TREO represents another defining milestone for Mount Ridley Mines and firmly positions the Mount Ridley project among the most significant rare earths and critical mineral regolith-hosted deposits in Australia.

In October last year, Mount Ridley tabled a maiden gallium mineral resource of 838.7 million tonnes at 29.3ppm for 24,584 tonnes of contained gallium, employing a 25ppm cut-off grade.

In November, the company followed up by defining a 33-kilometre-long corridor of new rare-earth and gallium targets from a geophysical reinterpretation, hinting that the current already massive resource footprint may be only the start.

Management has flagged its Mt Ridley project as a rare example of a Western Australian multi-element regolith-hosted system, where gallium, scandium and rare earths appear to occur together in near-surface saprolitic clay and lateritic horizons.

At the start of the new year, Mount Ridley then added a sizeable scandium resource of almost 368 million tonnes at 57.3ppm scandium for 18,855 tonnes of contained scandium metal from a separate prospect, also near Esperance.

However, the company says its core focus remains defining high-grade heavy rare earth zones, as they are likely to be the primary revenue generator, with scandium and gallium viewed as potential by-products.

Now armed with heavy rare earths alongside gallium and scandium, Mount Ridley’s next task is to keep the drill bit spinning and conduct metallurgical studies.

As the testwork progresses, the company’s attention will be centred on proving how the metals can be recovered, in what sequence, or whether a streamlined process can economically unlock a valuable suite of all of them from the system.

If the company can keep adding scale while firming up potential processing pathways, Mt Ridley is likely to stay firmly on the radar of punters watching out for the next strategically important supply story.

Is your ASX-listed company doing something interesting? Contact: matt.birney@wanews.com.au