The Côté Gold deposit is a new Archean low-grade, high-tonnage gold (± copper) discovery. It is described as a synvolcanic intrusion-related and stockwork disseminated gold deposit (Kontak et al., 2012, Katz et al., 2015, Dubé et al., 2015, Katz, 2016).

The Côté Gold deposit appears to correspond to the porphyry style. It is located in the southern limb of the Swayze greenstone belt part of the gold-rich Abitibi subprovince. At Côté, the zones of mineralization are centred on multi-phase magmatic and hydrothermal breccias, including a mineralized Au-Cu±Mo±Ag hydrothermal breccia that intrudes tonalitic and dioritic phases of the CIC (Katz et al., 2015). U-Pb zircon and titanite and ReOs molybdenite dating highlights the co-temporal link between magmatism and hydrothermal events (Katz, 2016). The hydrothermal breccia is itself overprinted by several types of hydrothermal alteration associated with mineralization.

Two different types of gold mineralization are recognized on IAMGOLD’s Chester township properties. The historically important mineralization can be termed quartz vein and fracture associated (Type 1), while the new Côté Gold deposit is interpreted by Kontak et al. (2012) as an Archean intrusion-related Au(-Cu) deposit (Type 2).

The Côté, Type 2, gold mineralization consists of low- to moderate-grade gold (±copper) mineralization associated with brecciated and altered tonalite and diorite rocks.

Several styles of Au mineralization are recognized within the Côté Gold deposit, and include disseminated, breccia-hosted and vein-type, all of which are co-spatial with biotite (± chlorite), sericite and sodic alteration.

Disseminated mineralization in the hydrothermal matrix of the breccia is the most important style of Au(-Cu) mineralization. This style consists of disseminated pyrite, chalcopyrite, magnetite, gold (often in native form), and molybdenite in the matrix of the breccia and is associated with primary hydrothermal biotite and chlorite after biotite.

The nature of the veins and fractures vary from stockworks to closely spaced, planar, subparallel sheeted vein sets. Stockwork mineralization cuts through all major rock types, but is most prominent in the more brittle tonalitic phases versus the dioritic phases and formed during the biotite alteration event (Katz et al., 2015; Katz, 2016). The mineralized sheeted veins and stockwork zones cut the hydrothermal breccia and therefore post-date the breccia-controlled mineralization.

Visible gold is observed in several settings within the deposit:

• Quartz ± carbonate ± biotite/chlorite veins: gold is observed to be hosted within the vein quartz and also along fractures cutting the vein. Sulphides include pyrite, chalcopyrite and pyrrhotite.

• Sheeted syn-intrusion-related veins: a set of subparallel, sheeted, millimeter to decimeter scale quartz ± carbonate ± chlorite veins with 0.5% to >50% pyrite ± chalcopyrite ± pyrhotite that commonly contain millimeter to centimeter scale barren sericite alteration haloes. These veins have been interpretated to be syn-intrusion in timing (Smith, 2016) and are also found outside the deposit within the CIC (e.g., Chester 1, 2 and 3).

• Magmatic-hydrothermal breccia: gold is more commonly observed in larger, welldeveloped shoots but is also observed in submillimeter veinlets of obvious hydrothermal provenance. At hand sample scale, gold appears to have some correlation with chlorite, sulphides, and magnetite.

• Miaroles: gold is observed hosted within miarole quartz, in fractures cutting primary miarole minerals, and within the host rock, proximal to the host/miarole interface commonly within a moderate to intense silica and/or sericite alteration halo. Importantly, the hydrothermal system is observed to replace the common carbonate cores of miaroles, which may subsequently host gold.

• Alteration related/ /disseminated: gold is observed proximal to veining and within apparent sodic ± sericite ± biotite/chlorite alteration halos. It is also found as isolated grains with no apparent control or related structure most commonly in tonalites, but also in diorites, commonly with moderate to intense sodic and/or sericite alteration of the host. It may also be associated with biotite/chlorite.

The hydrothermal breccia and the associated hydrothermal alteration zones are the material component of the mineralization providing the mineable widths and grades to the deposit. Areas outside of its significant development are likely not a significant contribution to economically important mineralization. The various gold-bearing quartz vein systems, also found immediately adjacent to the pit, serve to upgrade the hydrothermal envelope where they are present. The amount of gold contributed by these quartz vein systems to the deposit is difficult to determine but is thought to be of some significance to overall metal content.

The Côté Gold Project is designed as a conventional truck-shovel operation assuming 220 t trucks and 34 m3 shovels. The pit design includes four nested phases to balance stripping requirements while satisfying the processing plant requirements.

The design parameters include a ramp width of 35 m, road grades of 10%, bench height of 12 m, targeted mining width of 100 m, berm interval of 24 m, variable slope angles by sector and a minimum mining width of 40 m.

The smoothed final pit design contains approximately 196 Mt of ore and 559 Mt of waste for a resulting stripping ratio of 2.85:1. Within the 196 Mt of ore, the average grade is 0.94 g/t Au. These tonnages and grades were derived by following an elevated cut-off strategy in the production schedule.

The process plant will consist of a primary (gyratory) crusher, secondary crushing circuit, coarse ore stockpile (COS), tertiary HPGR crusher, ball mill , pre-leach thickening, whole ore cyanide leaching, CIP recovery of precious metals from solution, elution of precious metals from carbon, and recovery of precious metals by EW followed by smelting to doré. The plant will have facilities for carbon regeneration, tailings thickening and cyanide destruction.

The major design considerations in the plant layout were maintaining a single grinding line with gravity concentrators while minimizing pumping and piping requirements, and arranging the facilities efficiently considering the physical footprint limitations imposed by site geography.

Run-of-mine mill feed will be transported by 220t haul trucks to the gyratory crusher, where each truck will dump into the apron feeder system which feeds the gyratory crusher. The crushed material from the crusher will be discharged onto an apron feeder. This apron feeder will discharge onto the gyratory crusher discharge conveyor, which fills a secondary crusher screen feed silo. The contents of the silo will be fed to a set of secondary crusher screens by belt feeder; oversize (O/S) material from this screen will be sent to the secondary crusher and then routed back onto the gyratory crusher discharge conveyor; undersize material will be conveyed to the Coarse Ore Stockpile (COS) by the stockpile feed conveyor. The secondary crusher screen will also have the means to divert oversized material to a smaller emergency secondary screen O/S stockpile, to provide relief to the secondary crusher as needed.

Reclaimed crushed material from the COS will be conveyed to the HPGR along a belt outfitted with a scale to track tonnage. The HPGR circuit will have two screens to control grind size; oversize material will be recycled back to the HPGR feed belt. The first O/S recycle conveyor will have belt magnets and a metal detector to protect the HPGR from trash metal, as well as a belt scale to monitor recycled tonnage. Appropriately sized material will serve as cyclone feed within the ball mill circuit.

Underflow leaving the ball mill cyclones can go in one of two circuits. If low-grade mill feed is being processed, it can be sent directly to the ball mill, which operates in a closed circuit with the cyclone cluster to produce a product size of 80% passing 100 µm. Lime is fed into the ball mill as needed.

A 15% split of the cyclone underflow stream will be directed to the gravity circuit, distributed between two gravity concentrator screens, followed by a dedicated gravity concentrator assigned to each screen. Fluidization water and screen wash water, together with gravity concentrator tailings, will be collected in a launder and sent back to the cyclone feed pumpbox. Gravity concentrate will be collected in the storage hopper of an intensive cyanidation reactor. This reactor will be operated periodically to prepare material that discharges into an intensive cyanidation reactor. Cyanide and leaching aids will be added to the intensive cyanidation solution tank, and the resulting pregnant solution will be pumped to the pregnant solution holding tank.

Sized material from the cyclone overflow will be sent to one of two trash screens. Undersize from these screens will be sent directly to the pre-leach thickener feed tank. O/S will be routed to one of two trash dewatering screens, where the trash will be collected off the surface of the screen into bins. Undersize from the dewatering screens will also be sent to the pre-leach thickener feed tank.

The pre-leach thickener will initiate the gold leaching process. Further lime will be added to maintain pH at 10.5 to 11, to prepare for cyanide leaching. The slurry will be thickened, producing an underflow at 50% solids that will report to the leach circuit. The slurry will be split between two trains of leach tanks to achieve a leach residence time of 29 hours. Discharge from the leach trains will be recombined and sent to a CIP tank train in the carousel arrangement, for gold adsorption.

Loaded carbon from the CIP tanks will be pumped to the pressure elution circuit with two 10 t stripping vessels. Once gold has been desorbed, the carbon will be sent for regeneration in a 0.5 tph electric kiln. Quenching and screening will prepare the reactivated carbon for reintroduction into the CIP circuit.

Gold eluate, meanwhile, along with intensive cyanidation eluate, will be sent to EW cells to produce a gold-silver precipitate sludge. Loaded cathodes will be pressure-washed in place to produce a sludge containing the precious metals. The sludge will be filtered, dried, and then mixed with fluxes and smelted onsite to produce gold-silver bars.