Northern Minerals Ltd (ASX:NTU) will prioritise exploration in 2020 on high-grade unconformity targets of Browns Range Rare Earth Project in WA after recent success at Dazzler deposit confirmed the prospectivity of these targets.
The company has undertaken a trial gravity survey over Dazzler that revealed a distinct gravity feature, most likely related to hydrothermal alteration of the host rocks.
Hyperspectral studies have also been undertaken on diamond drill core from Dazzler that indicates a distinct hydrothermal alteration signature.
Based on the anomalous surface geochemistry at Dazzler and the fact that it has a distinct gravity and hyperspectral signature, these methods will be used as targeting tools for the next phase of exploration.
Northern Minerals’ managing director and CEO George Bauk said that exploration would continue to be a value-add for the company in 2020 at the project in the East Kimberley region.
With regards to the hyperspectral analysis, the company is investigating whether previously acquired airborne hyperspectral data can be interrogated in the hunt for Dazzler lookalikes.
Unconfirmity target potential
The potential for unconformity-related mineralisation is significant.
There is an 11-kilometre-long scarp where the unconformity outcrops that extends from Dazzler towards and across the Northern Territory border.
A further 130 kilometres of either exposed or likely to be shallow unconformity occurs within Northern Minerals tenure, centred on the Browns Range Dome.
Since the discovery of Dazzler in mid-2018, the company has been assessing and investigating the potential of unconformity-related deposits in and around Browns Range.
This work initially focused on the area around Dazzler and Iceman, including a mineralised zone between the two prospects.
Hydrothermal unconformity related rare earth deposit genetic model.
As a new discovery, Northern Minerals wanted to better understand the controls on mineralisation in order to assist with future targeting.
Company geologists first postulated the unconformity as a mineralisation target following anomalous geochemistry results in and around the scarp slope that highlights the unconformable contact.
Drilling in 2018 encountered mineralisation in the Gardiner Sandstone, above the unconformable contact with the Browns Range Metamorphics.
This was unexpected as all previous intercepts were within the older metamorphic unit.
Drilling also highlighted that the mineralisation in and around the contact was of a significantly higher grade than the other Browns Range deposits discovered to date.
Mineralisation is believed to be structurally controlled, with northwest-trending structures identified as being most likely to control mineralisation.
Drilling program underway
Following recent success at Dazzler, the company has today started a 4,000-metre reverse circulation (RC) program.
Around 60% of the program will be focused on infill and step-out drilling at the Gambit West and Cyclops deposits ahead of a planned mineral resource update in 2020.
The remaining program will assess greenfields exploration targets, including the Rogue prospect, about 6 kilometres along strike from Dazzler-Iceman, two gravity anomalies along strike from Dazzler-Iceman and Banshee South.
The drilling program is expected to take approximately 3-4 weeks to complete with assay results expected towards the end of the year.
Bauk said, “The implementation of ore sorting technology has highlighted the potential to increase the grade of feed going into the plant by approximately two times.
“The blending of higher-grade Dazzler-style ore into the run-of-mine feed has the potential to be a game-changer by significantly improve the economics of Browns Range.
“We look forward to supporting the exploration team as they continue to deliver for Northern Minerals and our shareholders.”
Pilot plant project
Production of heavy rare earth carbonate has started from the Browns Range Heavy Rare Earth Pilot Plant Project.
This three-year pilot plant project will assist the company to evaluate the economic and technical feasibility of mining at Browns Range and will provide the opportunity to gain production experience and surety of supply for the offtake partner.
Through this development, Northern Minerals aims to build the Western Australian operation into the first significant world producer of dysprosium outside of China.
The project has several deposits and prospects containing high-value dysprosium and other HREs, hosted in xenotime mineralisation.