Gold mineralization at Fort Knox Mine is hosted entirely within the Late Cretaceous (~92 Ma), Fort Knox granite pluton. The contact with the Fairbanks Schist is abrupt. Drilling indicates that the pluton contacts plunge steeply to the north and south and moderately to the east and west. The surface exposure of the pluton is approximately 1,100 m (3,609 ft) in the east-west direction and 600 m (1,969 ft) northsouth.

The Fort Knox Pluton has been subdivided into three phases based on grain-size and textural differences. Intrusion of a biotite-rich fine-grained granodiorite was followed by medium- grained porphyritic granite. The youngest intrusive phase is coarse-grained, porphyritic granite (Bakke, 1995). The texture is dominantly porphyritic, with megacrysts of quartz and k- feldspar, which become more sporadic in the fine- grained phase. The pluton is granite-granodiorite in composition, and the mineralogy of all phases is generally sub-equal amounts of quartz (30%), plagioclase (30-40%), and k-feldspar (20 to 30%) (Bakke, 1995; Blum, 1983).

The major structural trends controlling shear vein orientation and mineralization at the deposit- scale are defined by NW-trending, moderately to shallowly SW-dipping fault zones. The fault zones are typically filled with granulated white quartz, and range in thickness from 0.3 to 1.5 m. The zones have mixed groundmass alteration, with a range of phyllic and argillic alteration assemblages. In the vicinity of the fault zones, vein abundance increases and vein orientations are predominantly sub-parallel to the fault direction. The Monte Cristo Fault and Melba Fault zones are regional in extent and offset the Gilmore Dome Pluton south of Fort Knox and affect the orientation and geometry of the Fort Knox granite.

Gold occurs within and along the margins of pegmatite vein swarms and quartz veins and veinlets. Numerous SW-dipping fault zones influence the orientation of the vein swarms and the geometry of ore zones. Weak to moderate development of vein- andfracture-controlled phyllic, potassic, albitic, and argillic alteration styles is present. Gold is closely associated with bismuth (Bakke, 1995; McCoy et al., 1997). Gold occurs attached to bismuth- minerals, sulfide, and non-sulfide gangue, and as complex intergrowth or solid solution/exsolution texture grains with native bismuth, maldonite, bismuthinite, and/or molybdenite.

The overall sulfide content of the orebody is <0.10%. The orebody is oxidized to the depths of the drilling primarily along NW-trending, SW-dipping fault zones which contain abundant iron oxide and clay gouge along the margins.

Vein-types and associated alteration styles by abundance and relative importance to gold mineralization found at Fort Knox are:

1. Stockwork quartz veins and veinlets, ranging in thickness from micro-scale to 15 cm. These veins possess thin albitic alteration halos. Phyllic alteration envelopes that range in thickness from centimetre to multi-metre scale occur where stockwork veining is abundant near NW fault zones.

2. Pegmatite veins and veinlets: ranging in thickness from micro-scale to 8 cm. Composed of clear to grey quartz, large K-spar megacrysts, and micaceous clots. Potassic alteration halos, rarely exceeding 1 cm thickness, consist of an assemblage of variable amounts of secondary biotite and K- spar overgrowths on primary K-spar within the granite matrix. Veins variably altered with phyllic (quartz-sericite-pyrite) assemblage.

3. Low temperature fracture coatings and chalcedonic veins and breccia composed of zeolite- calcite-clay-chalcedony. Pervasive throughout the deposit in the form of fracture coatings and breccia zones. Argillic alteration halos as much as 7 m in width are developed adjacent to the larger chalcedonic breccia zones. These zones have been largely mined out to-date.

The Fort Knox deposit is classified as an Intrusion-Hosted Mesozonal deposit in the Reduced Intrusion-Related Gold Deposit (RIRG) style (Hart, 2005)

The Fort Knox Gilmore expansion will be an extension of current operations from 2021 to 2027. The existing operation is a conventional hard-rock open pit using drilling, blasting, loading, hauling and support functions.

Two new pushbacks have been designed and scheduled for the Gilmore expansion area: Phase 9 and Phase 10. Phase 9 contains approximately 156 million tonnes of ore and waste, while Phase 10 contains approximately 230 million tonnes of ore and waste, for a total 386 million tonnes of additional mining.

Initial mining of Gilmore is planned for 2019 as surplus mining equipment capacity is released from the Phase 8 East mining areas. Mining rates increase significantly in 2021 and 2022 as tonnages mined from Phase 8 East decrease. The mining of ore from Phase 9 roughly corresponds to the commissioning of the new Barnes Creek heap leach facility, which is the planned processing destination for the majority of the ore mined from both Phase 9 and 10. Phase 9 contains significant quantities of ore at shallow depths. Some ore mined from Phase 9 in 2019 through 2021 will be processed at the Walter Creek heap leach facility as sufficient capacity would not yet be available at Barnes Creek. Mining of Phase 9 is planned for completion in 2024.

Phase 10 mining is planned to start in 2022 when space and vertical advance constraints restrict the development of the Phase 9 pushback. Phase 10 contains little ore in its higher elevations and will not generate significant ore tonnages until 2025. Phase 10 will be completed in 2027, which represents the end of the extended mine life.

Fort Knox currently operates two ore processing lines: a mill operation consisting of crushing, grinding, gravity concentration, agitated cyanide leaching, and a carbon-inpulp (CIP) circuit; and a run-of-mine valley-fill cyanide heap leaching operation where gold is recovered using two parallel carbon-in-column (CIC) circuits. In the near future, an additional valley-fill heap leach pad will be constructed and operated in series with the existing heap leach pad. Gold is recovered from solution by electrowinning and poured into doré bars at the mill refinery.

The mill CIL processing facility is planned for closure in 2020, after which Fort Knox will become a 100% heap leaching operation. In post mill closure stage, it is planned that all ore materials will be directly processed without the use of stockpiles. All existing ore stockpiles at Fort Knox are scheduled for placement on the leaching facilities before the completion of mining, and as such there is no planned period ........