McArthur River Mine (formerly known as HYC) Zinc-lead-silver mineralisation occurs predominantly as ultrafine bedded parallel sphalerite and galena rich bands hosted by dolomitic and carbonaceous pyritic siltstones, graded beds and chaotic debris flow breccias. The HYC mineralisation covers an area of about two km2 and has an average thickness of about 55 m. It is 1.5 km west of the Emu Fault and separated from the fault by the Cooley Dolomite Member of the Barney Creek Formation and the Western Fault Block. The western margin of the deposit has been folded and eroded and the eastern margin is faulted against the Cooley Dolomite Member. The northern margin interfingers with sedimentary slump breccia derived from older McArthur River Group sediments to the north of the deposit. The southern margin, which has been down faulted by 100 to 200 m by the northeast trending Woyzbun Fault, is transitional into barren pyritic shale. The deposit is divided into seven mineralised intervals referred to as orebodies. Orebodies comprise shale with lesser amounts of sedimentary breccia and tuff. Number 1 orebody is used to refer to an interval of weak silver-lead-zinc mineralisation hosted by nodular dolomitic shale in the footwall sequence. In addition, there is a broad interval of weak silver-lead-zinc mineralisation hosted by nodular dolomitic shale in the immediate hanging wall, along the eastern margin of the deposit. The hanging wall sequence comprises interbedded dolomitic shale, ........

The open pit excavation is being undertaken in six stages, with the first three targeting the shallowest ore. Conventional drilling, blasting, loading and haulage methods are used.

After blasting, the overburden is excavated in horizontal benches to expose the target ore, which we then remove for processing. Separating the ore and waste at the mining stage ensures a relatively pure ore is fed to the processing plant.

Excavators with up to 550 tonne capacity load 175-220 tonne haul trucks with ore or waste to be taken to stockpiles or the waste rock piles. The majority of the overburden rock from the open pit is stored at the North Overburden Emplacement Facility, or waste rock pile.

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