The Dark Star deposit is considered to be Carlin-type, sedimentary-rock-hosted deposits. Precious metal mineralization is generally submicroscopic, disseminated, and hosted principally in sedimentary rocks, with some mineralization in felsic dikes and sills as well.
The Dark Star Main (“Dark Star Main”) and Dark Star North (“Dark Star North”) zones, which comprise the Dark Star deposit, are hosted primarily within Pennsylvanian-Permian rocks, with minor amounts of gold mineralization found in the Chainman Formation and Tertiary conglomerates. The deposits are centered along the roughly north-south Dark Star fault corridor, within which is a horst block and associated silicified zone bounded by the West fault and Dark Star fault. Gold mineralization in the horst block is hosted in the middle, coarse-grained conglomeratic and bioclastic limestone-bearing unit of a Pennsylvanian-Permian undifferentiated sequence interpreted to be equivalent to the Tomera Formation. Mineralization dips steeply to the west near the surface at Dark Star Main and Dark Star North, but dips less steeply at depth at Dark Star Main.
The mineral reserve estimate for Dark Star is based on an open pit mine plan and production schedule and a gold price of $1,275 per ounce. The Dark Star mineral reserve estimate comprises a Probable Mineral Reserve of 23.88 million tonnes averaging 0.83 g/t Au, representing a total of 640,000 contained ounces of gold and a Proven Mineral Reserve of 5.43 million tonnes averaging 1.39 g/t Au, representing a total of 243,000 contained ounces of gold.
The mineral resource estimate for Dark Star was constrained within a $1,500 per ounce of gold optimized pit shell using gold cut-off grades of 0.14 g/t Au for heap leach material (oxide and transitional) and 1.0 g/t Au for sulphide material. The Dark Star mineral resource estimate comprises a Measured Mineral Resource of 5.86 million tonnes averaging 1.31 g/t Au, representing a total of 246,000 contained ounces of gold, an Indicated Mineral Resource of 26.86 million tonnes averaging 0.78 g/t Au, representing a total of 675,000 contained ounces of gold, and an additional Inferred Mineral Resource of 2.48 million tonnes averaging 0.70 g/t Au, representing a further 56,000 contained ounces of gold. Mineral Resources are inclusive of Mineral Reserves.