Ann Mason is hosted by several phases of the Jurassic-age Yerington batholith, and younger quartz monzonite porphyry dykes (Jqmp-a, Jqmp-b and Jqmp-c). Copper mineralization primarily occurs within a broad zone of main-stage potassic alteration containing chalcopyrite and bornite. An assemblage of chalcopyrite-epidote or chalcopyrite-epidotequartz mineralization locally overprints main-stage potassic alteration and copper mineralization.

Within the Yerington district, Tertiary volcanic rocks, Mesozoic host rocks and coppermolybdenum porphyry deposits have been rotated 60 degrees to 90 degrees westward by Miocene normal faulting and extension. As a result, mineralized intercepts in vertical drill holes through Ann Mason represent approximately horizontal intervals across the original pre-tilt geometry of the deposit.

The Ann Mason deposit has the characteristics of a typical, large copper-molybdenum porphyry system. Projected to the surface, the 0.15% Cu envelope covers an area approximately 2.8 km northwest and up to 1.3 km northeast. At depth, this envelope extends more than a kilometre below surface. The mineralization remains open in most directions.

Within the 0.15% Cu envelope the highest grades occur within a 200 m to 800 m thick, westplunging zone that surrounds the intrusive contact between granodiorite (Jgd) and porphyritic quartz monzonite (Jpqm). Within this zone, copper grade is dependent on vein density, sulphide species, frequenc ........

The Mason deposit is a large tonnage, copper-molybdenum deposit and is planned to be a traditional open pit shovel/truck operation with a copper sulphide mineral processing plant producing commercial grade copper and molybdenum concentrate.

Mining operations in the pit are designed to be performed from 15 and 30-metre-high benches using large-scale mining equipment including 10 5/8-inch diameter rotary blast hole drills, 74 cubic-yard electric mining shovels, a 55 cubic-yard hydraulic shovel, a 37 cubic-yard front-end loader and 290-tonne capacity haul trucks. During the 27-year operation, the mine plan achieves peak mining rates until year 13, then reduces by about half of the original mining rate from year 14 to 20 as the strip ratio drops. The remaining seven years assumes the processing of rehandled ore from stockpiles.

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