An interim mineralogical report on Asra Minerals’ Yttria deposit at its Mt Stirling project in Western Australia’s eastern Goldfields has confirmed the heavy rare earths discovery is suitable for low-cost processing.
Asra submitted 10 samples containing elevated rare earths and yttrium from its recent discovery to the University of Queensland’s Julius Kruttschnitt Mineral Research Centre for a mineralogical characterisation study.
The initial examination has revealed rare earths, along with yttrium and scandium at Yttria are mostly hosted by secondary oxide minerals common in the regolith such as asbolane, goethite and cerianite, that have been found to be easier to separate.
The seemingly idle association gives rise to the high concentrations initially detected using the aqua regia digest assaying technique that first led to the deposit’s discovery.
Importantly, the study indicated high refractory rare earths minerals xenotime, monazite and bastnaesite, known to inhibit digestion and separation, are only present as very fine-grained inclusions in silicate minerals.
Asra’s Rare Earth Consultant, Ken Collerson said: “It is unlikely that the REEs and yttrium are associated with the highly refractory minerals xenotime and monazite as these minerals would not have dissolved in the initial Aqua Regia leach assays.”
“The initial mineralogy results are therefore extremely positive for the development of a cost-effective critical metals separation process at Yttria.”
Collerson says the initial findings indicate Yttria is a regolith hosted deposit, in contrast with the more common hard-rock style, such as Lynas Rare Earths’ Mt Weld deposit or ionic clay style deposits found throughout China.
Further higher resolution mineralogical studies on the rare earths yttrium and scandium are continuing in tandem with metallurgical test work to evaluate recovery of the metals.
Approvals are also in place for a 50,000m drilling bonanza intended to evaluate and define the extent of the unique inventory of critical minerals and heavy rare earths at the Mt Stirling project.
Asra says its proposed campaign will include resource definition drilling at the Yttria heavy rare earths prospect, in preparation for a maiden mineral resource estimate at the target.
Additionally, drilling is planned to define and extend the mineralisation at its nearby Wishbone prospect, stretch the mineralisation between Yttria and Wishbone and sniff out regional-scale rare earths and critical mineral accumulations that are thought to be speckled around the project’s Arktos fault.
Asra’s flagship Mt Stirling project offers a unique and potentially lucrative cocktail of critical rare earths — dysprosium, terbium, neodymium and praseodymium — that, along with the low radioactive composition, put the project among only a few in the world.
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By Matt Birney
