Viridis Mining & Minerals (ASX: VMM) has widened the high-grade rare earths footprint of the Cupim South deposit at its Colossus project in the Brazilian State of Minas Gerais, with new discoveries delivered from outside the operation’s known mineralised area.
Recent auger step-out drilling on an adjoining mining licence revealed multiple zones grading higher than 7000 parts per million total rare earth oxides (TREO), including the valuable heavy rare earths, dysprosium and terbium. The company says both the high-grade TREO intersections and the newly-discovered heavy rare earths were from surface or near-surface, with many drillholes ending in even higher-grade mineralisation.
Importantly, the Cupim South Extension remains open in all directions, with the highest-grade portion of the deposit extending south-east onto its adjoining licence and the bulk of the area still to be tested. Management believes the Cupim South deposit and its extension are only a fraction of the total mineralised system within the licence area.
Recent assays returned from the campaign showed 8m at 7856ppm TREO from 2m, with the last 4m going 10,980ppm and including higher-grade dysprosium and terbium oxide at 117ppm.
Further hits of 12m at 5427ppm TREO from surface and ending in 5171ppm included 12m at 126ppm dysprosium and terbium and 14m at 3060ppm TREO from surface, ending in 2682ppm including 6m at 166ppm of the two heavy rare earths.
The consistent and high-grade results across the extension of the Cupim South Deposit are remarkable and showcase the homogenous nature of the mineralisation which encompasses the area well beyond the current Resource.
Viridis Mining & Minerals chief executive officer Rafael Moreno
The company says it has begun a reverse-circulation (RC) drill program to fully test the thickness and grades of its compelling Cupim South and the extension zone.
Viridis earlier this month unveiled a significant maiden resource of 201 million tonnes at a stellar 2590ppm TREO at its Colossus ionic-adsorption-clay (IAC) project. As part of its resource reveal, the company noted that magnet rare earth oxides (MREO) came in at 668ppm – an impressive 26 per cent of the TREO.
Management says Cupim South was the “standout” among its deposits, producing 28 million tonnes at a world-class grade for an IAC project of 3061ppm. The deposit comprising the bulk of the resource is its Northern Concessions area, with 147 million tonnes at 2516ppm TREO and a MREO content coming in at about 26 per cent.
Assays from the recent drilling of the Northern Concessions show elevated heavy rare earths, in addition to higher grades than previously seen in the area. Results included 16m at 6231ppm TREO from 2m including 8m at 7336ppm with 37 per cent MREO and 70ppm dysprosium-terbium.
Additional hits show 13m at 4368ppm TREO from 4m including 6m at 5305ppm with a healthy 41per cent MREO and 98ppm dysprosium-terbium and 23m at 3743ppm TREO from 1m including 9m at 6391ppm with a whopping 48 per cent MREO and 126ppm of the two heavy rare earths.
Another of Viridis’ promising deposits is Fazenda Cocal, which had a previous hit of 13m at 7632ppm ending with the last 5m at 10,689ppm and 82ppm dysprosium-terbium.
Management says mineralisation at the deposit appears widespread, with drilling conducted 4km east of the discovery zone returning 5m at 3861ppm TREO from 2m and ending 5760ppm within the last 1m. It also noted that Fazenda Cocal and its Centro Sul deposits are prioritised for further drilling, with aggressive exploration to continue to help management understand the extent and grade of the mineralisation so a subsequent resource upgrade can be established.
Colossus sits within the Poços De Caldas Alkaline Complex in south-east Brazil. Management rates the play as the world’s premier IAC project, with its high-grade TREO and the MREO showing an important dysprosium and terbium content of 32ppm.
There is also the potential for the heavy rare earth component to be increased on the back of the latest results. With previous exceptional bulk-sample magnet metallurgical recoveries and the possibility of expanding the resource, especially at Cupim South, the project seems to be continually growing.
IAC rare earths projects have many advantages over their hard-rock counterparts. Despite lower grades and lower recoveries, their extraction is levels cheaper from an operational and capital perspective.
Benefits include mineralisation occurring at surface, minimal stripping, clay-hosted soft material requiring no blasting, no crushing and milling and a simple one-step leaching process. There is also no requirement for a tailings dam, low levels of uranium and thorium and no radioactive tailings.
The company plans to conduct infill drilling at its known deposits, continue greenfields exploration seeking higher-value rare earths and undertake metallurgical testing to assist with mine planning. A much-anticipated scoping study is expected in the coming months and further work will be carried out on permitting activities.
With an ever-growing project on its hands, Viridis seems to be in a good place with the demand for rare earths looking set to increase in the not-too-distant future.
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