Clean Air Metals (TSX-V:AIR) believes there is scope to increase the tonnage of the “high-grade” sections of the resource at Thunder Bay North Critical Minerals Project after receiving the latest drill results.
Drilling at the Current deposit has returned intersections of 50.7m @ 4.52 grams per tonne (g/t) platinum, 4.38g/t palladium, 0.99% copper and 0.53% nickel – or 13.74g/t platinum equivalent and 4.36% copper equivalent – from 82m.
This intercept included a higher grade section spanning 30.7m @ 6.35g/t platinum, 6.10g/t palladium, 1.32% copper, and 0.69% nickel from 102m.
Clean Air reported grades of up to 20.4g/t platinum, 21g/t palladium, 4.2% copper and 2.18% nickel from a 0.5m interval at 188.9m depth.
This hole was the second in the 10-hole program to intersect massive sulphides near the base of the intrusion.
CEO Mike Garbutt says the new results confirm Clean Air’s belief that the tonnage of the highest-grade parts of the Current deposit is likely underestimated by the most recent resource model – largely because of an inadequate drilling density in these areas.
“Additional geophysical modeling and tightly-spaced drilling is expected to allow us to quantify the highest value mineralisation within both the Current and Escape deposits,” he says.
“We believe that a more robust, low-tonnage high-grade production model anchored by these high-grade areas is attainable.”
The summer drilling program targeted near-surface, high-grade zones within the Current deposit to better define their lateral continuity and tonnage potential.
Thunder Bay North has an indicated resource of 14 million tonnes containing 1.2 million ounces of platinum and palladium, 56,800 tonnes of copper, and 33,800 tonnes of nickel.
Clean Air says nine of the 10 holes completed in the program intersected “significant widths of high-grade mineralisation”, averaging over 6g/t combined platinum and palladium.
The revised geological model for the high-grade areas at Thunder Bay North employs flow processes similar to those associated with alluvial gold processes.
According to Clean Air, these results provide confidence and “proof of concept” that continued success in the expansion of the high-grade pods along strike is possible with tighter drilling.
Vice President of Exploration Lionnel Djon says the results of the proof-of-concept drilling at Current provide a high level of confidence that the high-grade pods have a regular periodicity that can be predicted using 3D geophysical models and that their tonnage potential is likely greater than previously appreciated.
“We are excited to follow up on these encouraging results and begin the job of delineating these high-grade domains to support an independent estimation of their tonnage and grade,” he says.
Thunder Bay North is known to carry massive sulphides in pockets and embayments at both the Current and Escape deposits.
Clean Air says these occurrences demonstrate the potential for these deposits to host additional massive sulphide, and continued exploration work is needed to identify the feeder zone for this material.
The company is in the process of developing a follow-up exploration program designed to discover new high-grade zones within the two deposits, which are located 3km apart, and a resource delineation program to support an independent resource estimate of the highest-grade domains in both deposits.
Clean Air is investigating the potential for a smaller tonnage, high-grade and low-capital cost mine, which it believes is supported by the results of the recent drilling program.
The higher-grade mineralisation is spatially distributed in distinct and separable zones that allow for targeted extraction using traditional open-stope mining methods.
This approach will form the foundation for a future technical study.
To further de-risk Thunder Bay North, Clean Air is considering the potential extraction of a bulk sample.
The aim is to validate the high-grade mining approach, as well as quantify the metallurgical performance of a toll milling scenario on a larger scale.
The Thunder Bay North Project sits about 50km northeast of the city of Thunder Bay in Ontario, Canada.
Write to Angela East at Mining.com.au
Images: Clean Air Metals
