Australian explorer Mount Burgess Mining (ASX: MTB) has consolidated all drill hole data relating to the polymetallic Nxuu deposit in Western Ngamiland, Botswana, in response to a request to show more clearly the known mineralised domain and continuity of mineralisation.
The company’s drill hole map originally showing five separate targets – the South West Area, South East Area, Mid West Area, Mid East Area and the Northern Area – has now been reduced to just two and highlights only those holes drilled to date.
South West Area shows just the mineralised domains of four holes (NXDD037, NXRC027, NXDD003 and NXDD036) and their assay grades, while the other 20 holes are shown in the remaining area.
By presenting the data in this way, Mount Burgess believes it has shown more clearly the continuity of the mineralised domain and assay grades of Nxuu.
Nxuu is a basin-shaped deposit where the zinc-lead mineralisation in a totally oxidised quartz wacke extends to a maximum depth of 60m.
Extractive metallurgical test work has shown that grades of up to 93% zinc can be recovered in 12 hours via an acid leach process, with potential to produce zinc metal on-site.
Metallurgical work on a similar deposit in Australia showed lead carbonate could be successfully extracted using methane sulphonic acid, allowing for lead to also be recovered on-site.
This test work has yet to be conducted on samples from the Nxuu deposit.
Recent metallurgical test work on Nxuu mineralisation has shown that vanadium pentoxide grading up to 80.4% can be recovered on-site through a standard oxide flotation process using a hydroxamate collector for recovery.
Of the 24 holes drilled to date into the Nxuu deposit, approximately 58% of every hole has been shown to contain recoverable zinc-lead-vanadium mineralisation.
Of the remaining 42%, approximately 17% consists of Kalahari sand cover, leaving only 25% as insignificantly-mineralised quartz wacke.
The average depth to the base of the 24 holes so far drilled is 40m, confirming the deposit’s shallow nature.
A review of results from earlier drilling campaigns, which included assaying for vanadium, has shown that Nxuu’s content extends beyond the zones of zinc-lead mineralisation and increases the overall metal-endowed domains within the mineralised quartz wacke.
Mount Burgess said it is evident that vanadium will represent a substantial additional credit to the Nxuu development.
During the COVID-19 lockdown period, Nxuu samples containing the silvery white metalloid germanium were sent to the University of Naples for testing to determine the nature and structure of the host mineral.
If germanium is shown to be recoverable as part of normal mining operations, it could represent a further credit for the project as the metal is currently trading at $2,615 per kilogram.
Further samples have also been sent to the Commonwealth Scientific and Industrial Research Organisation (CSIRO) for host mineral test work.
Mount Burgess plans to develop the Nxuu deposit as a potentially shallow, low-risk and low-cost operation.