Significant economic Ni-Cu-PGE-Au mineralization occurs within quartz diorite offset dykes at Copper Cliff Mine offset orebodies and the Totten Mine orebodies. They can extend for many kilometres into the Sudbury Structure wall rock, and may be radial or concentric to the contact of the SIC with distinct, sharp contacts. Quartz diorite is the main component of South Range offsets, and of distal (>3 km from sic contact) portions of North Range offsets. Footwall breccia also occurs here as sheets and discontinuous lenses concentrated along the lower contact of the SIC, and as a major component of some of the offset dykes.

Mineralization consists of zones of disseminated blebby and massive Ni-Cu-PGE-Au sulphide that is spatially associated with inclusion-rich phases of quartz diorite, as well as with local structural complexities of the dykes. Ni-Cu-PGE-Au deposits have longer dip lengths then strike length and contain at least 5% sulphide. Areas between orebodies consist of barren quartz diorite or weakly mineralized inclusion-rich quartz diorite.

The Copper Cliff Mine uses Vertical Retreat Mining, Blasthole Stoping (slot-slash variation) for the bulk of the production. Sill pillars are recovered using Uppers Retreat Mining. The Copper Cliff Mine Life Of Mine Plan also makes provision for limited use of mechanized cut-and-fill mining.

Ore is transported from the Ontario Operations mines and third party ore suppliers by rail and/or truck to Clarabelle Mill where it is blended together. The ore is crushed and ground, with the majority of the pyrrhotite removed through magnetic separation and sent to a designated waste storage area in the Copper Cliff tailings impoundment area. The remaining ore undergoes selective flotation to produce a bulk nickel and copper concentrate grading 14% Ni equivalent and approximately 8.5% Cu and 11% Ni. The concentrate is dewatered, mixed with custom concentrate feed and high-grade silica flux and conveyed to the smelter. The rock tailings are used for mine backfill, building dams in the Tailings area, or disposed of in the Copper Cliff tailings impoundment area.

Concentrate produced from the flotation process is used to generate a high copper concentrate by depressing the pentlandite, thus allowing the copper to float. The concentrate is then filtered to produce a filter cak ........