The Cortez deposits are Carlin-type sedimentary rock-hosted deposits.
A secondary deposit model that is applicable to the Cortez Complex is an intrusion-related gold model.
Cortez mineralization occurs approximately between elevations 1,630–1,240 m, is approximately 400 m wide northeast–southwest by 1,219 m long northwest–southeast, and ranges in thickness from approximately 90–455 m.
Mineralization is hosted within the Roberts Mountains Formation and the Hanson Creek Formation.
A series of north–northwest trending and northeast trending faults cut the lithologies, with mineralization forming where these faults intersect shallow east-dipping thrust breccia zones (thrust duplexes).
Most of the Cortez NW Deep higher-grade gold mineralization (<3.43 g/t Au) occurs in two zones lying between the 1,280–1,325 m elevations beneath the old Cortez open pit floor. One zone consists of an oxidized and strongly altered thrust zone within the Roberts Mountains Formation and the other is an unoxidized, sulfide-bearing thrust zone at the top of the Hanson Creek Formation.
Mineralization becomes dominantly refractory at about 1,280–1,325 m elevation.
Breccia gold mineralization is hosted in hydrothermally brecciated and fractured rocks that are spatially associated with the WSW dipping faults and attendant structures. Altered, matrixsupported breccia bodies contain the highest gold grades and are surrounded by “crackle” breccias and highly-fractured rock with moderate gold grades continuing outwards to lessfractured rocks with lower grades. Most of the Breccia mineralization dips moderately southwest enveloping the west–southwest-dipping faults.

PIPELINE
The main Pipeline deposit is a 15–90 m thick, tabular zone lying at about 150–180 m beneath the surface. The deposit dips at a low angle to the east and extends over an area of 230 m north– south by 460 m east–west. Drilling indicates the deposit extends to at least 427 m depth.
South Pipeline consists of two zones, a shallow zone starting at 20–46 m depth and a deep zone starting at 300 m. The shallow zone occupies an area of approximately 550 m by 610 m, north and east respectively, and exhibits both low-angle and high-angle structural controls on gold distribution. The deep zone occupies an area 60 m north–south by 180+ m east–west, is up to 76 m thick and is more closely associated with high-angle structures.
Within the Pipeline deposit, gold is hosted in both sheared and unsheared rocks, and in association with all alteration types. Gold occurs in association with silica, pyrite, hematite, and illitic or sericitic matrix material. Gold grains are coarser in open spaces and in fracture fillings, and finer-grained when associated with silica, pyrite and hematite.
At South Pipeline, microscopic gold is commonly associated with silica, in replaced matrix and quartz veinlets, and in association with limonite after pyrite.
Mineralization is predominantly characterized by oxides, and sulphidic and carbonaceous refractory material. Carbon content in the deposits is highly variable and occurs generally in the Devonian Wenban Limestone and Roberts Mountain Formation.
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.

CROSSROADS
Crossroads is to the south of, and along strike with, the Pipeline deposit, but is at a greater depth, consistent with the south–southeasterly dip of the host formations into the basin.
The deposit has dimensions of 1,700 m by 500 m along strike and extends from about 1,320 m to 890 m in elevation above sea level. The Crossroads deposit consists of two mineralized zones: an upper stratiform zone along the Horse Canyon–Wenban Formation contact and a deeper zone controlled by an east– northeast-striking, west dipping (20° to 25°) structural zone that cuts across stratigraphy.
Gold mineralization is associated with anomalous arsenic, antimony, and thallium. Gold occurs in solid solution within arsenian rims on hydrothermal pyrite in primary ore, and as sub-micron sized free gold particles in ores which have been oxidized. Common gangue minerals include pyrite, abundant calcite, oxide and arsenate minerals, as well as clays.

GOLD ACRES
The Gold Acres deposit lies just to the north-west of the Pipeline Open Pit, in an exposed window of the upper plate of the Roberts Mountain Thrust. The deposit has dimensions of 450 m by 900 m along strike and extends from approximately 1,650 m to about 1,430 m in elevation above sea level.
Two mineralizing phases are recognized. The first consists of skarn calc-silicates and sulfide assemblages; the second comprises gold mineralization within the imbricate fault zone. Some gold was also deposited in the high angle structures and along the Roberts Mountains Thrust above the imbricate fault zone. Gold is present as disseminated submicroscopic particles. Gangue minerals include pyrite, calcite, quartz, melanterite, azurite, jarosite, realgar and various base metal sulfides and calc-silicate minerals related to the skarns.

ROBERTSON
The deposit is about 2285 m long, 910 m wide, and approximately 400 m thick. Robertson is an igneous related gold system. Gold mineralization is found in Upper Plate siliciclastics of the Devonian Slaven and Silurian Elder formations, as well as inside Eocene intermediate composition igneous rocks, primarily diorite and granodiorite. Mineralization is primarily concentrated around the Tenabo Stock in three main areas: Gold Pan in the northwest, Porphyry in the east to northeast, and Altenburg Hill in the southeast. Gold mineralization overprints an initial contact metamorphic hornfels event and a subsequent chalcopyrite– pyrrhotite–pyrite–chlorite–actinolite skarn event.

CORTEZ HILLS COMPLEX
The Cortez Hills Complex consists of two in-situ and connected Carlin-type orebodies with differing geometries and an exotic satellite deposit (Pediment deposit) that was eroded and redeposited adjacent to the sub-cropping Cortez Hills orebody.
The underground portion of the Cortez Hills deposit consists of the Breccia Zone, the Middle Zone and the Lower Zone (subdivided into Lower Zone A, B, C and D).
The conical-shaped Breccia Zone mineralization extends from a near surface elevation of 1,783–1,240 m, terminating just east of the Middle Zone. It is approximately 300 m wide with a northwest trend, and varies in width from 75–580 m.
The Middle Zone occurs between elevations 1,318–1,166 m, is approximately 550 m wide northwest–southeast by 400 m long northeast–southwest, and ranges in thickness from 3– 80 m.
The Lower Zone lies at an elevation of 1,298 m to the northwest and 933 m to the southeast, extends 1,310 m northwest–southeast, varies in width from 440 m in the north to 150 m in the south, and ranges in thickness from 20–80 m. An emerging area below Lower Zones C and D has mineralization extending to 759 m elevation along the Hanson Fault.
The Pediment deposit covered an area of 900 m x 180 m, ranged in elevation from 1,785– 1,615 m, and was about 75 m thick.
Breccia gold mineralization is hosted in hydrothermally brecciated and fractured rocks that are spatially associated with the Voodoo Fault and its attendant structures. Mineralization within the Middle and Lower Zones lies at depth to the west and southwest of the Breccia Zone, occurring as tabular, sub-horizontal to shallow dipping zones. Mineralization in the Lower Zone is typically refractory in the north, transitioning to dominantly oxide as the zone plunges deeper to the south.

The Cortez Complex consists of both open pit and underground mines. Open pit mines consist of Pipeline, Crossroads, and Cortez pits, while underground operations consist of Cortez Hills Underground (Middle Zone, Lower Zone, and Deep South), and Goldrush Underground operations (Red Hill, Crow’s Nest, 3 ½, Ranch, Meadow).

Open pit mining is conducted using conventional open pit techniques and equipment.

Cortez Hills Underground is a mechanized decline access underground mine based upon the mining of up to 4,700 t/d of ore and waste. The Middle Zone is being exploited using cut-and-fill mining methods and minor amounts of longhole stoping; while the Lower and Deep South Zones are planned to be mined by longhole stoping.

Goldrush underground is a mechanized decline access underground mine with intensive lateral development required to open up the orebody. The primary mining method will be longhole stoping with minor amounts of cut-and-fill where the orebody geometry does not allow for longhole stopes.

As the permitting process progresses, mine development has continued in the Red Hill mining zone at Goldrush. Development is currently focused on the upper portions of Red Hill, where dewatering of the ore body is not required. Test mining of underground longhole stopes commenced in November 2021.

OPEN PITS
Open pit ore is mined by a conventional shovel-truck process at the rate of approximately 12.4 Mt/a with a LOM stripping ratio of 6.5:1 (waste to ore ratio). Mining occurs in two separate areas approximately 19 km apart, at the Cortez Pits, and the Pipeline/Crossroads open pits.

Mining at Cortez Hills (CHOP) was completed in May 2019, and the ramp between the Pediment open pit and Cortez Hills remains to ensure completion of Buttress.

The following design criteria are used for the Pipeline and Crossroads open pits:
• Pipeline: 15 m bench height;
• Crossroads: 12 m bench height with 24 m double benching in favorable rock formations;
• Alluvium inter-ramp wall slope angle varying from 35–42°;
• Fresh rock inter-ramp wall slope angles ranging from 37–45° depending on material type and wall orientation;
• Bench face angles ranging from 65–70° depending on material type;
• 10% maximum haul road grade;
• 36.6 m wide haul roads.

The Crossroads open pit operations will cease in 2026, at which stage the pit will be 1485 m long, 1,645 m wide, and 535 m deep.

The Pipeline open pit has one phase remaining, PL10. PL10 at completion will be 835 m long, 720 m wide, and 365 m deep.

Cortez Pits will be mined out in 2024, after three years of active mining. There are two remaining phases, CP01 and CP02. CP01/CP02 will be 915 m long, 915 m wide, and 365 m deep.

The various open pits are scheduled considering the ore and waste quantities, ore grades, and the centralization of activity to the extent possible. Average total daily open pit mine production from the Cortez Complex is estimated to be 389,000 t/d in 2022, an average of 273,000 t/d for 2023–2025, and 74,000 t/d for the year 2026. All daily average production rates include a combination of ore and waste.

UNDERGROUND
Cortez Hills Underground Mining is mechanized, with large-scale equipment using a combination of cutand-fill mining with cemented rockfill, and primary and secondary longhole stoping with cemented and uncemented backfill. The Middle Zone is primarily mined through cut-and-fill mining methods. The Lower Zone, including Deep South Zone, is mined through longhole stoping methods.

In the cut-and-fill stopes, headings are cycled using conventional drill/blast/muck/support on a round-by-round basis. Material is loaded into haul trucks and hauled to the materials handling system which crushes and conveys the material to surface. Top-cut headings are typically 5.5 m wide by 4.6 m high and undercut widths vary from 5.5 m to 9.1 m, depending on ground conditions and ore geometry, with 4.6 m heights.

Longhole stopes are being mined using 18 m sublevels with a series of primary and secondary longhole stopes. Development will typically be 5.5 m high and the primary and secondary stopes are planned to be 7.6 m wide and 10.7 m wide, respectively. Primary stopes will be mined in shortsections to maintain stability and each section will be filled with CRF after mining. Secondary stopes will be mined after primary stopes have been completed. Where the ore zone is more than 18 m high, the stopes will be stacked vertically, as needed, to extract the ore. Longholes are planned to be vertical down holes from the upper sublevel.

The Deep South Zone mining plan is based on longhole stoping, with delayed backfill, in a sequence of primary and secondary stopes.

Cortez Hills Underground Mining is conducted using drill and blast development and drilled and blasted long hole stopes. At present, blasting is conducted using emulsion as the primary explosive in both development and stoping. Stopes are blasted using an 89 mm blast hole, and development is conducted using 48 mm blast holes. All explosives are stored following all regulations in the underground powder magazine.

Based on Mineral Reserves only, the current Cortez Hills Underground production schedule is based upon the mining of up to 4,700 t/d of ore and waste from the Middle, Lower, and Deep South Zones.

Based on Mineral Reserves only, the current underground mine life is estimated to be nine years (2022–2030).

Access
The Cortez Hills underground operations are accessed by twin declines driven to the upper level of the deposit. The two declines from the F-Canyon extend for approximately 2,134 m at a -6% grade to the 1,454 m level. Access for the Middle and Lower Zones is by a spiral ramp adjacent to the orebody giving access to the Middle Zone at the 1,195 m level and onto the Lower Zones A at 1,227 m and Zone C at 1,222 m.

The twin declines are interconnected at regular intervals and these connections contain air doors to separate the intake and exhaust airways. An additional set of twin declines, called the rangefront declines, for access to the Lower Zone and the Deep South Zone, have been developed. The western range-front decline provides additional means of egress and the eastern range-front decline contains the materials handling system where a conveyor is installed throughout the entire length of the decline.

Ore and Waste Haulage
With the conveyor installed in the range-front declines, there are ore passes for material, where practical, and ore haulage from other areas to a series of four bins that are located at the base of the conveyor system. The bins enable segregation of the oxide and refractory ore types.

Waste material that is generated typically is hauled by truck to mining areas that are queued for waste backfilling.

Backfill
A dual purpose CRF/shotcrete batch plant is located at the mine portal in F-Canyon. Mine trucks are loaded at the portal elevation and the backfill is taken into the mine as a back haul. The backfill portion of this plant is only in service when the underground batch plant is down or if haulage were to redirected out of F-Canyon declines in the event the underground materials handling system or underground batch plant has maintenance activities. There is also a shotcrete batch plant located at the portal. Mix trucks haul the prepared shotcrete mix to the mining face.

As part of the development plan for the Middle, Lower and Deep South Zones, a CRF plant was constructed closer to working areas underground. The plant has been set up so that rock and cement can be delivered from surface via boreholes.

All production openings are currently backfilled with a designed backfill with a 4.826 Mpa unconfined compressive strength based on -5.1 cm crushed rock, 35% fines, and 6% cement binder. Cylinder tests indicate that the cemented rockfill strength consistently exceeds the design strength.

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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. Mill No. 1 was placed on care and maintenance at the end of October 1999. The roaster has been inactive since 1995 and has been demolished. Mill No. 2, also referred to as the Pipeline Mill, was constructed in 1997, and is operational.

Ore from the Cortez Complex can either be processed on site in the oxide processing facilities
or transported to the Goldstrike roaster, Goldstrike autoclave, or Gold Quarry roaster, parts of the Carlin Complex, for refractory ore treatment.

HIGHER-GRADE OXIDE ORE MILLING
Mill No. 2, or the Pipeline mill currently includes crushing, semi-autogenous grind (SAG) mill, ball mill, grind thickener, carbon-in-column (CIC) circuit for the grind thickener overflow solution, CIL circuit, carbon stripping and reactivation circuits, and a refine ........