Si6 Metals has nailed high-grade hits of up to 5475 parts per million total rare earth oxides (TREO) from surface, including magnet rare earth oxides (MREO) up to 36 per cent, at its Caldera joint venture (JV) project in the notable mining region of Minas Gerais in Brazil.
The company has today reported that its seven-hole auger drilling program intersected mineralisation in every hole from the project that sits inside the Poços de Caldas Alkaline Complex – one of the world’s biggest geological intrusive systems.
Management says the high-grade intercepts from surface indicate the potential for an ionic-adsorption clay (IAC) discovery, with drilling consistently intersecting saprolite clays.
Hits from surface included 5m at 4526ppm TREO with 34 per cent MREO including 2m at 5475ppm and 36 per cent MREO. A further slice from surface of 9m at 2579ppm TREO with 25 per cent MREO included 2m at 4265ppm TREO and 36 per cent MREO.
A thicker 16m at 2179ppm TREO from surface was intersected with 30 per cent MREO.
The valuable rare earths neodymium and praseodymium (NdPr) made up a significant portion of the magnet rare earths, with low levels of the heavy rare earths dysprosium and terbium also found.
The highly sought-after NdPr rare earths are a primary component of industrial magnets widely used in electric and hybrid motors and generators, clean energy technologies and wind turbines.
Si6 Metals managing director Jim Malone said: “The excellent first batch of auger results reported here is demonstrating that our Caldera joint venture prospect has the potential to develop into a discovery zone with every hole drilled intercepting clay-hosted rare earth mineralisation. Importantly, the drilling has returned significantly high proportions of high value and strategically critical magnet rare earth oxides up to 36 per cent.”
The company says there are some assays still pending for the auger drilling at Caldera, in addition to outstanding assays from the Caldera South rare earths prospect and the Padre Paraiso deposit’s lithium drill program.
Si6 now plans to test the depth of mineralisation at Caldera further, as several holes ended in mineralisation from the shallow depths drilled. It intends to review data from all three drill programs when they are complete and depending on funding requirements, it will then determine the best targets for reverse-circulation (RC) drilling to greater depths in a bid to ascertain the true potential of its rare earths and lithium prospects.
The Caldera, Caldera South and Padre Paraiso projects are operating in a 50:50 JV structure with Foxfire Metals as part of the original deal struck on 10 existing Brazilian licences for rare earths and lithium. Si6 also recently negotiated to hold 70 per cent of any future licences that are agreed to between the two parties and placed into the Brazilian critical minerals JV.
Under the terms of the new deal, Si6 will fund the expenditure incurred on applying for or acquiring any new ground through to a feasibility study, in accordance with the original JV agreement. The costs will form part of the $1 million minimum expenditure commitment for the first 12 months of the JV.
Foxfire – which brings significant on-ground Brazilian geological expertise to the JV – will have the first right of refusal on any new turf.
Si6 recently secured a further 54-square-kilometre plot of highly-prospective land to add to its original Caldera licence, giving it a second licence to enable a serious pursuit in its search for high-grade rare earths.
The additional land borders Meteoric Resources’ Caldeira project where high-grade ionic-clay rare earths have been discovered and an inferred mineral resource of 409 million tonnes at 2626ppm TREO has been announced.
Si6’s project is also near Viridis Mining & Minerals’ compelling Colossus project where that company has produced several ridiculous ionic-clay hits as high as 25,075ppm and 24,894ppm. It has also discovered even higher grades at depth.
The company believes ionic-adsorption clay deposits generally have lower grades near surface and improve with depth, with average magnet-based rare earths grades typically increasing with deeper drilling.
Si6 believes it may be just scratching the surface of what may be at Caldera and is keen to move to the next stage of drilling to hopefully confirm a “fully-fledged” ionic-adsorption clay-style discovery.
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By Craig Nolan
