Goldstrike mineralization is best described to be in the class of sedimentary rock-hosted Carlinstyle deposits. The Carlin-style class of gold deposits are not unique to the eastern Great Basin. They are characterized by concentrations of very finely disseminated gold in silty, carbonaceous, and calcareous rocks. The gold is present as micron-size to sub-micron-size disseminated grains, often internal to iron-sulphide minerals (arsenical pyrite is most common) or with carbonaceous material in the host rock. Free particulate gold, and particularly visible free gold, is not a common characteristic of these deposits; significant placer alluvial concentrations of gold are therefore not commonly associated with eroded Carlin-style gold deposits.

All Carlin-style deposits in the Great Basin have some general characteristics in common, although there is a wide spectrum of variants. Anomalous concentrations of arsenic, antimony, and mercury are typically associated with the gold mineralization; thallium, tungsten, and molybdenum may also be present in trace amounts. Alteration of the gold-bearing host rocks of Carlin-type deposits is typically manifested by decalcification, often with the addition of silica, fine-grained disseminated sulphide minerals, remobilization and/or the addition of carbon, and late-stage barite and/or calcite veining. Small amounts of white clays (illite) can also be present. Decalcification of the host produces volume loss, with incipient collapse brecciation that enhances the pathways of the mineralizing fluids. Due to the lack of free particulate gold, Carlin-style deposits generally do not have a coarse-gold assay problem common in many other types of gold deposits.

Deposit configurations and shapes are quite variable. Carlin-type deposits are typically at least somewhat stratiform in nature, with mineralization localized within specific favourable stratigraphic units. Fault and solution breccias can also be primary hosts to mineralization.

Most of the gold discovered at Goldstrike can be characterized as finely-disseminated “micron gold”, incorporated in the lattice of arsenical pyrite grains, in association with strong pervasive silicification. Very little of the mineralization at Goldstrike is preserved in this form, as most of the pyrite has been oxidized to iron oxides including hematite, goethite and limonite. As discussed above, gold is paragenetically late with respect to silicification, such that most of it is concentrated along fractures. Gold is geochemically correlated with arsenic, silver, antimony, thallium and mercury, although oxidation tends to disperse elements such as arsenic, making the correlation less strong.

Faults associated with gold mineralization typically have large zones of calcite veining or calcite vein breccias developed along them. These calcite zones can be up to 15.2 m wide in places. It is assumed that these calcite veins are late with respect to Carlin-style mineralization, and barren, although early reports of gold production state that coarse gold was associated with the calcite veins. These same fault zones are in places intruded by thin basaltic dikes and sills that locally host coarse gold along their margins and internal steep sheers.

Extensive mineralization is also found in favourable Paleozoic carbonate, sandstone and shale units, particularly where they are in proximity to the basal Claron Formation unconformity or large faults. In general, the Paleozoic rock units at the unconformity young east to west in the Main Zone Covington Pit area, with the Redwall Limestone in contact with the Claron Formation in the eastern Main and Hamburg pit areas and the Queantoweap Sandstone in contact with the Claron Formation north of the Covington Pit. The Callville Limestone is in contact with the Claron Formation in the Moosehead pit area and probably at Beavertail. In general, the upper portion of the Callville Limestone is the most favourable unit to host mineralization, while the Redwall, Scotty Wash, Chainman and the middle sandy member of the Pakoon Dolomite also host mineralization. The Queantoweap Sandstone and the upper and lower dolostone members of the Pakoon Dolomite tend to be barren of mineralization. As well, the basal Claron Formation adjacent to these units tends to be less well endowed with gold mineralization than when it is adjacent to more favourable Paleozoic units. This generalization can be extended to locations in the southeast part of the property where the Claron Formation is in contact with the Grapevine Wash Conglomerate. It is possible that the relative lack of calcite associated with these formations may be a factor in the lack of gold mineralization, or lack of a permeability/porosity contrast.

The style of disseminated mineralization at Goldstrike is similar to other sediment-hosted gold deposits in the Great Basin, where elemental gold is located within the lattice of arsenical rims on pyrite grains. Mineralization drilled and mined to date is oxidized, and thus the original presence of arsenical pyrite is inferred from the presence of scorodite with iron oxides and by the elevated arsenic content of mineralized rocks. Few other minerals have been noted in association with gold. These include very local occurrences of orpiment, realgar, stibnite and stibiconite.

The PEA Study utilizes open pit mining with mine planning based on economic pit shells generated by mine planning software. Mine production is planned at 22,500 tonnes per day or 8.2 million tonnes per year of leach feed (mineralized) material. With an average waste to leach feed material strip ratio of 1.2 to 1, the average mining rate is approximately 50,000 tonnes per day of leach feed and waste material. The open pit mining at Goldstrike was designed utilizing an owner-operated, conventional mine fleet of front end loaders and trucks.

The project consists of a ROM heap leach with a carbon plant for solution recovery and on-site smelting of gold and silver into doré bars.

ROM material will be transported directly from the open pits to the heap and dumped by mine haul trucks. Before stacking on the heap, lime will be added to the trucks at a rate of 1.2 kg lime per tonne in a dedicated staging area along the mine haul road.

Material will be stacked in 9-meter high lifts. Stacking will be assisted by a low-pressure track dozer to push and spread material in preparation for leaching. Dozer ripping to facilitate improved percolation will also be performed after each lift has been stacked to the determined height.

The annual tonnage of ROM material stacked is approximately 8.1 million tonnes.

After each leach cell has been stacked and dozer ripped, the irrigation system will be installed. Dripline emitters will be used to apply a dilute cyanide solution, at an average appli ........