Goldstrike Complex.
The Goldstrike deposits are Carlin style deposits. Carlin deposits comprise stratabound disseminated gold mineralization hosted by Silurian-Devonian carbonate rocks that have been metamorphosed to varying extents. The deposits are hydrothermal in origin and are usually structurally controlled. The carbonate host rocks are part of an autochthonous miogeoclinal carbonate sequence exposed as tectonic windows beneath the Roberts Mountains allochthon.

Cortez.
The Cortez deposits are “Carlin” style sedimentary rock-hosted and porphyry/epithermal deposits. Deposits are localized at contacts between contrasting lithologies, metamorphosed to varying extents. They can also be discordant or breccia-related. The deposits are hydrothermal in origin, are usually structurally controlled and at Cortez are hosted in Lower Plate carbonate strata exposed by two erosional windows through allochthonous Upper Plate siliclastic units; the windows are on either side of Crescent Valley.

Mineralization consists primarily of submicron to micrometre-sized gold particles, very fine sulphide grains, and gold in solid solution in pyrite. Gold is disseminated throughout the host rock matrix in zones of silicified and decarbonatized, argillized, silty calcareous rocks and associated jasperoids. Gold may occur around limonite pseudomorphs of authigenic pyrite and arsenopyrite. Major ore minerals include native gold, pyrite, arsenopyrite, stibnite, realgar, orpiment, cinnabar, fluorite, barite, and rare thallium minerals. Gangue minerals typically comprise fine-grained quartz, barite, clay minerals, carbonaceous matter, and late-stage calcite veins.

In the Cortez district, the favoured host rocks for gold mineralization are the Wenban Limestone, followed by the Horse Canyon and Roberts Mountain formations. Mineralization reflects an interplay between structural and lithological ore controls in which hydrothermal solutions from intrusives moved to favourable porous decalcified limestone. Mineralized host rocks are predominantly characterized as oxides, along with sulphidic and carbonaceous refractory material. Carbon content in the deposits is highly variable and occurs generally in the Wenban and Roberts Mountain Formations.

Supergene alteration extends up to 656 ft depth resulting in oxide ores which overlie the refractory sulphides. Alteration has liberated gold by the destruction of pyrite and resulted in the formation of oxide and secondary sulphate minerals which include goethite, hematite, jarosite, scorodite, alunite, and gypsum.

Goldstrike Complex.
Conventional open pit and underground mining consisting of the Betze-Post open pit and the Meikle and Rodeo underground mines.

Meikle is a high-grade ore body which is mined by transverse longhole stoping, underhand drift and fill mining methods. Rodeo is a trackless operation, using two different underground mining methods: long-hole open stoping and drift-and-fill.

Cortez.
The Cortez Hills underground mine is accessed by twin declines portaled in the old Cortez Gold F canyon pit. The Pipeline and South Pipeline deposits are mined by conventional open-pit methods.

Cortez Hills pit dimensions: 2km long x 1km wide x 400m deep and Typical bench height 15m.

The underground mining method is underhand cut and fill with a cemented rock fill. Ore is drilled with two boom jumbos, blasted on a round by round basis, loaded into haul trucks, and hauled to surface. Parallel 5m wide by 5.5m high and 3 km declines with crosscuts at every 150m.

Historically, Cortez ore was processed in a 1,800 stpd CIL plant called Mill No. 1, as crushed ore on heap leach pads, and refractory ore was pre-oxidized in a circulating fluid bed roaster. The crushing and leaching circuits were built in 1969; the roasting circuit was completed in 1990. The Mill No. 1 processing facilities were placed on care and maintenance in 1999.

Ore from Cortez can either be processed on site in the oxide processing facilities or transported to the Goldstrike operation for refractory ore treatment.

OXIDE ORE MILLING
Mill No. 2, or the Pipeline mill, was commissioned in 1997 to process oxide ore from the Pipeline open pit mine. The treatment plant currently includes crushing, SAG mill, ball mill, grind thickener, carbon-in-column (CIC) circuit for the grind thickener overflow solution, CIL circuit, tailings counter-current-decantation (CCD) wash thickener circuit, carbon stripping and reactivation circuits, and a refinery to produce ........