The Ellen Open Pit, formerly known as the Crean Hill No.2, is located near the mutual contact of the Sudbury Nickel Irruptive, the Creighton granite, and the older Middle Precambrian mafic metavolcanics of the Elsie Mountain formation.

The ore is found in breccia at the nickel irruptive contact where this contact swings sharply northward. There is also sulphide mineralization along the contact to the east, Graham Township, and there is mineralization to the west in Denison Township. The norite contact dips about 80° north to the west of the pit and about 50° northwest to the northeast of the pit. The norite is sheared and brecciated along the contact and ore is found in both brecciated greenstone and norite. The ore is "rocky", containing abundant rock and mineral inclusions. The affinity of chalcopyrite for rock fragments is well-displayed. There is a quartz-carbonate vein exposed in the west wall of the pit. The carbonates are evidently ankeritic because they weather brown. Blebs and masses of chalcopyrite are found in the vein.

The mineralization occurs mostly in the leucocratic tonalitic sub-layer breccia at the base of the Sudbury Irruptive. The hanging wall consist of late Middle Precambrian norite and quartz diorite type norite while footwall rocks are Early Precambrian mafic and granite gneisses. The orebody can be subdivided into three zones: The Hanging wall zone, which makes up about 10% of the ore, is a series of discontinuous sulphide lenses in the hanging wall norite breccia. Most of the ore occurs as disseminated blebs but stringers and massive ore are also present. The Main zone, which contains 70% of the ore, consists of a series of ore lenses in a tonalitic breccia with numerous inclusions of gneiss and norite. The ore occurs mostly as breccia ore which consist of patches and stringers of sulphides. The Deep zone, which makes up the other 20% of the ore, is an irregular shaped concentration of massive sulphide stringers which are wholly enclosed in rocks of the granitic complex. This zone is separate from the main zone by at least 30.5 meters of granitic gneiss.

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 ........