SerpentinizationI was interested in Canada Nickel's news release of April 13, 2023. In it, they discussed one of their drill holes in their Midlothian Township program:
"MID23-01 was collared toward the centre of the intrusion and intersected 343 metres of highly serpentinized dunite starting at 2.0 metres and ending at 345 metres. Selected samples were taken for metallurgical testing (QEMSCAN) that confirmed the samples were well-serpentinized with varying amounts of heazlewoodite and awaruite. The hole encountered two narrow (~0.5 metres) dikes".
Awaruite is something that RT Minerals should keep an eye on within their Kenogaming-Pharand1- Pharand2 properties. Awarite is derived from serpentinized peridotite, while heazlewoodite is found in serpentinized dunite and peridotite.
A potential example of the relationship between what may be weakly serpentinized peridotite/dunite ultramafic rocks (RT Minerals-Kenogaming Twp) and a highly serpentinized ultramafic sill (Canada Nickel (CNC)-Midlothian Twp) is presented on magnetic maps Map 81379 and Map 60424 respectively.
The magnetic total field Intensity of the Kenogaming anomaly vs the Midlothian anomaly is approximately 1000 nanoTeslas vs 7000 nanoTeslas respectively.
Overlaying Map 60424 on Canada Nickel's map (Figure 1, from their news release of April 13), I note that Holes 1,2 and 3 were drilled into a magnetic low, while Hole 4 was drilled into the north conductor, which has direct magnetic correlation. Holes 1,2 and 3 intersected only dunite, while Hole 4 intersected pyroxenite, peridotite and dunite. To me then, the north conductor (and high magnetite) is related to the first two rock types, pyroxenite and peridotite, which are relatively unaltered. I also suspect that the dunite (core) is weakly magnetic, compared to the outer peridotite and pyroxenite, because it has been highly serpentinized. Also, could the magnetic low in the middle of the magnetic anomaly be considered a suture zone? If anyone has any other thoughts on this, comments would be much appreciated.
Is there a correlation between either the intensity of serpentinization (alteration) or brucite and nickel grade?
Do the 2 strong east-west conductors on Map 60424, which also have direct magnetic correlation, represent two horizons of high concentrations of magnetite?? Is this why CNC went after the magnetic low, because of its alteration to serpentinite??
If you look at the south side of the Midlothian Twp anomaly, you will note an isolated EM response that has a correlated magnetic anomaly. If this latter data was processed into a second vertical derivative, the anomaly would be more clear as an isolated response. This particular area could also be an embayment or trough within the lower lithology, making this EM response a very attractive target. The ultramafic sill is dipping slightly to the south.
An isolated example to what CNC may also be seeing at their Midlothian Twp property could be the following, taken from FPX Nickel's website:
"The FPX Nickel (FPX) District, near Fort St. James, BC, which is the company’s (FPX) flagship nickel property, is a greenfield discovery of nickel mineralization in the form of a naturally occurring nickel-iron alloy called awaruite. It represents a promising target for bulk-tonnage, open-pit mining. This deposit contains little or no sulphides, meaning it has little or no capacity to generate acid mine drainage. Initial metallurgical test work demonstrates the nickel-iron alloy is recoverable using conventional two-stage grinding and magnetic separation, followed by gravity concentration – and does not require chemical reagents thereby significantly reducing another potential environmental impact".