The inclusion of recent infill and extension drilling data and a revision of the marginal cut-off grade has resulted in a 53% increase to the maiden mineral resource estimate at Ionic Rare Earths’ (ASX: IXR) flagship Makuutu project in the Republic of Uganda.
The resource now stands at 78.6 million tonnes at 840 parts per million total contained rare earth oxide (TREO) at a cut-off grade of 300ppm TREO minus cerium oxide, eclipsing the original March estimate of 47.3Mt at 910ppm TREO at a 500ppm cut-off.
The revised cut-off grade has been considered consistent with peer ionic adsorption rare earth element clay projects using similar processing technologies.
Ionic said the updated estimate was based on a total 903m of core drilling conducted within the Makuutu central zone, which covers less than 20% of the larger Makuutu prospective area.
An in-situ TREO content comprising heavy rare earth oxide (25%) and critical rare earth oxide (37%) confirms Makuutu as a globally significant project, with the potential to offset diminishing Chinese ionic adsorption clay reserves.
Ionic chairman Tony Rovira said the new resource estimate was enabled by metallurgical optimisation and preliminary economic assessment activities conducted during a March haitus to the company’s drilling program brought about by COVID-19.
“The updated estimate demonstrates Makuutu’s potential to be a globally significant and strategic alternative supplier of heavy and critical rare earths,” he said.
“We aim to further increase these figures when drilling recommences in July, and [we believe] the potential to expand the mineral resource size and confidence category is substantive,” Mr Rovira added.
The resource grade has been maintained at the upper end of expectations defined in the project’s exploration target, estimated using a combination of existing drilling results and a projection of criteria such as grade and thickness of mineralisation in untested yet prospective areas.
“The cut-off changes derived from project specific inputs have been validated as consistent with peer ionic adsorption rare earth projects and further reinforce our expectations [for Makuutu] to be a low-cost rare earth oxide producer,” Mr Rovira said.
One of biggest ionic clay deposits outside of China
Comprising two granted retention licences and one exploration licence, the Makuutu project is 100% owned by Uganda’s Rwenzori Rare Metals.
Ionic currently has a 31% shareholding in Rwenzori and has previously entered into a deal to increase this to 60% by meeting pre-determined expenditure commitments.
Makuutu is significant in size and believed to be potentially one of the largest ionic clay deposits outside of China, with grades consistent with these types of deposits.
Ionic clay-hosted rare earth deposits are a substantive source of existing critical and heavy rare earth production in China.
The mining and processing of these deposits is generally simpler than hard rock deposits, which provides significant operating cost advantages.
Resumption of drilling
Mr Rovira said a resumption of drilling activities will include infill work within Makuutu’s central zone to upgrade resource confidence, and testing of the full 26km mineralisation corridor from the eastern to western zones.
Samples will be provided for metallurgical testwork over a broader area of the project.
At mid-morning, shares in Ionic Rare Earths were up 10% to $0.011.