The Betze-Post mineralization, the largest deposit in the Carlin Trend, is subdivided into sub-deposits which, from east to west, are the Deep Post, Post, Betze, West Betze, and Screamer. Other zones within the pit are North Betze, West Barrel, and North Screamer.

Overall, the open pit deposits consist of five stacked zones which, when combined, average 500 ft thick and 600 ft wide but may attain a thickness of 700 ft, a width of 1,100 ft, and a length of 3,400 ft.

Five generations of pyrite mineralization have been recognized at the Betze-Post open pit. Early stages of diagenetic pyrite, and coarse grained pyrite in the metamorphic aureole of the Goldstrike diorite, are barren. Early hydrothermal, very fine grained pyrite and marcasite grains of the third generation are coated by a 25 µm thick rind and cut by micro-veinlets of arsenic and gold bearing pyrite of the fourth generation. Barren, late hydrothermal coarse grained pyrite and marcasite is accompanied by barite and stibnite. Sulphides make up approximately 5% by weight of the ore, locally up to 20%.

The gold bearing arsenian pyrite may be subdivided into coarse grained sulphides at ±200 µm diameter and fined grained at 10 µm to 20 µm, with the latter carrying proportionately much more gold. Gold at 0.05 µm to 0.1 µm is occluded in the iron sulphides. Approximately 10% to 20% of the gold is free, 20% to 30% is held in the fine grained pyrite/marcasite, a few percent is contained in coarse pyrite, and the balance is in very fine pyrite associated with clay.

The Betze-Post open pit is a truck and shovel operation. With completion of the 3rd NW phase targeted for March 2019, the open pit has three remaining phases (4th NW, West Barrel, and 5th NW). The ultimate pit will measure approximately two miles east to west, 1.5 miles north to south, and have an average depth of approximately 1,300 ft.

The Bazza Waste Dump is located to the southwest of the open pit. The Life of Mine (LOM) plan includes the Clydesdale Dump to the west and backfilling of the southwest and southeast portions of the open pit. Internal to the pit is the Betze Portal, which connects to the Rodeo underground mine; the North Post Portal, which connects to North Post and Rodeo underground; and the Betze Portal 2, which is used for ventilation.

Previously the Post Portal connected to Newmont’s Deep Post underground mine, however, this area has since been backfilled.

The pit design is based on 40 ft benches in the waste and, where possible, 60 ft benches in the ore mined in 20 ft cuts. Slopes vary based on location.

Goldstrike process facilities provide the capability to treat single refractory ore (sulphidic) and double refractory ore (sulphidic and carbonaceous) through roasting or pressure oxidation. The roaster circuit accommodates Goldstrike open-pit and underground ore as well as Cortez Hills Open Pit (CHOP) and Cortez Hills Underground (CHUG) ore. A blended feed to the roaster is required to control the circuit heat balance. Pressure oxidation also receives a blended feed from stockpiles and operates as either alkaline or acid POX dependent upon feed carbonate/sulphide ratios. Pressure oxidation is followed by CaTS leaching, also referred to as the Thiosulphate Leach Conversion (TLC) with an RIL adsorption circuit for gold recovery. Respective facilities include:

1. An autoclave circuit consisting of:
• Primary crushing
• Two parallel SAG Mill-Ball Mill grinding circuits with pebble crushing
• Five parallel autoclaves capable of alkaline or acid POX
• Two parallel CaTS leaching circuits including RIL and electrowinning for gold recovery
• A refinery producing doré bullion from both autoclave and roaster circuits

2. A roaster circuit consisting of:
• Primary and secondary crushing
• Two parallel dry grinding circuits
• Two parallel dual stage fluid bed roasters
• Roaster off-gas handling and mercury recovery systems
• A slurry neutralization circuit
• A CIL circuit with carbon stripping, carbon acid wash, carbon regeneration (ADR) and electrowinning for gold recovery
• Cyanide destruction circuit


Tailings impoundment and reclaim water from CIL versus RIL processing are kept separate with Roaster-CIL tailings stored in the North Block Tailings Dam Facility (NBTDF) and POXCaTS-RIL tailings stored in Tailings Storage Facility 3 (TSF3).