AVZ Minerals has laid claim to having the world’s biggest hard-rock lithium deposit after pumping up the resource at its Manono play in the Democratic Republic of Congo to a whopping 574 million tonnes at 1.63 per cent lithium oxide.
The eye-popping figures come on the back of the company tabling a maiden resource for its Carrière de L’Este pegmatite of 173 million tonnes at 1.58 per cent lithium oxide for 2.73 million tonnes of lithium oxide. The total Manono resource also includes the 401 million tonnes at 1.65 per cent lithium oxide at its existing Roche Dure deposit at the south-western end of the main southern pegmatite exposure known as the Kitotolo Sector.
The Carrière resource estimate is based on mapping, sampling, initial metallurgical testwork and 11 diamond drillholes in fence pairs at a section spacing ranging from 200m to 250m for a total of 3853.31m of drilling along a pegmatite strike length of 1.2km.
AVZ says the selected drillhole layout was adopted to simplify wireframes and facilitate the fleshing out of the important aspects of the Carrière pegmatite, including its lithology, size, shape and orientation and the tenor of mineralisation. It adds that an updated geological model will subsequently be used to design future drilling programs or mine designs.
The areas of historical mining at the site, mostly for tin, and the persistent strike and width of the pegmatite outcrop that is almost 500m wide along the 1.2km strike, suggests the resource area remains grossly under-evaluated and has potential to be grown further – potentially by orders of magnitude.
The company believes the entire 13km strike of the collective Manono pegmatite will need testing by well-spaced deep holes to help resolve the possibly varying orientations between zones to identify thick depth extensions and likely the feeder systems.
The northernmost Manono Sector is the longest strike exposure at more than 6.5km, while the southern Kitololo Sector is about 4.8km long. The Carrière zone is at the south-western end of the northern main pegmatite exposure in the Manono Sector and about 7.5km north-east from the existing Roche Dure lithium resource at the south-west extremity of the Kitololo Sector.
The two sectors are separated by an intervening 2km zone of no pegmatite exposure, including the partial cover of the 2.2km-diameter Lake Lukushi and its surrounding recent sediments. AVZ says high-grade surface samples have been recovered from the spillway of the Lake Lukushi dam, south-west of the most southerly drilling on Carrière.
It appears almost certain that the unexposed pegmatite in the lake area has been downfaulted, implying that potential exists for the intrusive to extend along strike to the south-west beneath the lake towards the northernmost Tempete pegmatite in the Kitololo Sector.
All the intervening zone is well outside the company’s current geological model boundary, which provides management with the confidence that pegmatite-hosted resource extensions might exist and could greatly extend the potential resource base for the project.
The project is about 500km due north of Lubumbashi, the capital of the Katanga Province, in the south-east of the DRC. It is adjacent to the Manono and Kitatolo townships.
Tin was first discovered at Manono in 1910 and the area was prospected between 1910 and 1920. The original developer, Géomines, was granted a mining licence and production began in 1919. The weathered pegmatite was discovered in 1925 during an exploration program that had been focused on eluvial tin deposits.
Since the 1960s and up to as late as the 1980s, little additional exploration was undertaken, except for the prospecting of old mine dumps for tin and spodumene.
However, the most intense period of tin mining took place between 1919 and 1980, during which more than 100 million cubic metres of ore was processed to yield 185,000 tonnes of tin as cassiterite concentrate at an average grade of 1.33kg per cubic metre.
In 2019, AVZ took 54 samples of lithium-mineralised and non-mineralised pegmatite, with grades in the range of 0.009 to 4.13 per cent lithium oxide and an average grade of 1.46 per cent lithium oxide, from three diamond drillholes. The work ultimately showed that the Carrière mineralogy was similar to Roche Dure.
Later, initial metallurgical testwork on diamond-core samples gave the company the confidence that it could produce a potentially saleable spodumene concentrate from the Carrière pegmatite.
The Manono pegmatites are hosted by quartz-mica schists and are homogeneous mineralogically, with tin grades up to 2kg per cubic metre, tantalum up to 100g per cubic metre and for the lithium ore mineral spodumene, up to 25 per cent or 1.6 per cent lithium oxide.
The project comprises a single tenement that covers about 188 square kilometres. It was granted in December 2016 for a period of five years and is renewable in accordance with the DRC’s Mining Code.
A significant part of the originally granted project area, amounting to more than 60 per cent of the entire north-east corner of the company’s original permit, has been subsumed by a competing claim.
The company is vigorously defending its rights to the Manono project and in May last year, it entered voluntary suspension in relation to the ongoing dispute that has been subject to several additional extension requests for arbitration and voluntary suspension.
This giant lithium resource seems to have plenty more to give if AVZ can get a clear run at its complete evaluation and it could also turn out to be a game-changer for global lithium supply at a time when it is most needed.
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By Doug Bright
