The mafic/ultramafic intrusions of the Lac Rocher Suite are intruded into gneissic rocks of the Rocher Complex. They occur as isolated, typically strongly magnetic bodies ranging from less than 1 km to over 2.5 km in size. Work on the Lac Rocher intrusion itself suggests they are zoned with an inner ultramafic core comprised of pyroxenite/peridotite and an outer gabbroic rim (click here to view the Lac Rocher deposit geology map).
At the Lac Rocher deposit, nickel sulphide mineralization appears to occur in an embayment in the outer gabbroic rim of the intrusion. Nickel sulphides occurs as disseminated to locally massive accumulations both in the lower pyroxenite and outer gabbroic phases of the intrusion and in the proximal paragneiss unit. Massive sulphide accumulation is limited to and occurs in the paragneiss with assay results exceed 10% nickel in the massive sulphides.
A 2008 PEA completed for Victory Nickel on the Lac Rocher deposit outlined a small, high-grade, ramp-accessible resource of 0.3 million tonnes grading 1.57% nickel, 0.58% copper and 0.053% cobalt. While this resource is too small to support attractive economics, it does demonstrate the high grade potential of the intrusive bodies in this area.
In 2019 Balmoral announced the discovery of the Bluenose Zone on the RUM North property. The Bluenose Zone is characterized by disseminated nickel-copper-PGE sulphide mineralization an ultramafic host discovered in isolated outcrop on the southern portion of the RUM North Property. The previous metal rich nickel sulphide mineralization at Bluenose exhibits significantly higher PGE:Ni and Au:Ni ratios than the nearby Lac Rocher deposit. The host intrusion is one of four intrusions on the RUM North property and has never been drill tested.