Mount Polley is an alkalic porphyry copper-gold deposit. It lies in the tectono-stratigraphic Quesnel terrane or Quesnellia, which is characterized by a Middle Triassic to Early Jurassic assemblage of volcanic, sedimentary and plutonic rocks which formed in an island arc tectonic setting outboard of the ancestral North American continental margin. Quesnellia hosts several major porphyry copper deposits such as Highland Valley, Copper Mountain, AftonAjax, Gibraltar and Mount Milligan, all generated by early Mesozoic, calc-alkalic or alkalic arc magmatism.

In the Mount Polley region, the Triassic arc rocks are assigned to the Nicola Group and comprise alkalic basaltic to andesitic volcanics and sedimentary rocks, which are intruded by sub-volcanic stocks; all are overlain by post-Nicola, Early Jurassic clastic rocks and rare volcanics. Mount Polley itself is a complex of alkalic intermediate porphyritic intrusions and related magmatic-hydrothermal breccias. It was emplaced into the Nicola Group in the Late Triassic around 205 million years ago. The intrusive complex is about 6 km long (north-northwest) and 3 km wide, lying between Polley Lake in the east and Bootjack Lake in the west. The intrusions range from diorite (oldest) to monzonite (youngest) and are marginally undersaturated in silica. The Mount Polley Intrusive Complex is in the centre of the Mount Polley property; the remainder of the property is underlain mainly by Nicola Group volcanics and p ........

Mount Polley mine operations were suspended in May 2019, and the mine restarted operations in late June 2022. Mining Methods - conventional shovel, truck and open pit mine. With a developing underground mine. Open Pit Mining Equipment The current open pit mining operation at Mount Polley utilizes a conventional truck and shovel fleet with drilling and blasting prior to excavation. The fleet includes a mixture of diesel and electrically powered equipment for drilling, excavating and dewatering. Material Handling Ore mined from the pits is hauled to either the primary gyratory crusher located immediately adjacent to the mill or to nearby stockpiles. Waste material at Mount Polley occurs in one of two types: non-acid generating waste (NAG), and potentially acid-generating waste (PAG). NAG/PAG designations are made on the basis of the neutralizing potential ratio (NPR) of a given material. This NPR is calculated by performing acid-base accounting (ABA) using carbon and sulfur assays from blasthole cutting samples. Sampling is performed on a one sample per 20,000 tonnes basis. All rock with an NPR less than 2.0 and a sulfur content greater than 0.1% is designated as PAG and stockpiled. PAG waste is estimated to constitute approximately 27% of the waste tonnage in the life-of-mine plan. PAG waste, as a condition of operating permits, must be submerged for long-term storage at the end of mine life. As such, all PAG rock is selectively mined and temporarily stored ........

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