The Pogo deposit consists of three distinct zones: the Liese, East Deep, and North Zone vein systems. The Liese and East Deep consist of stacked, shallow-dipping quartz veins, whereas the North Zone veins are steep and could be feeders to the Liese and East Deep. Individual veins range from 0 to 65 feet thick and have a variety of quartz vein filling and replacement textures, suggesting multiple episodes of mineralization. Gold occurs as 1–25 micron grains in arsenopyrite, along fractures, and as inclusions in native bismuth and other gold–lead–bismuth–tellurium minerals. The age of the mineralization overlaps with nearby granitic intrusions at around 104 million years. There is lack of consensus over the origin of the veins, with evidence for both orogenic-vein and deep-seated intrusion-related-vein genesis.

The economically significant gold mineralisation on the project occurs in two gently dipping, sub-parallel, massive quartz veins, each of up to 30 m in thickness (generally 4 to 12 m), L1 and L2 of the Liese Zone, while a third, L3 has been indicated at depth. These veins are within mylonitic shear zones associated with thrusting, and are locally accompanied by sheeted, en echelon or stockwork developments. The princpal hosts are biotite-quartz-feldspar paragneiss, although all other lithologies are cut. Where the veins cross intrusives they tend to split and become stockwork zones. Each vein is made up of 0.5 to 5 cm thick bands, parallel to the vein margins, composed of quartz with pyrite-arsenopyrite ±pyrrhotite ±chalcopyrite, cut by dolomite-sericite and Fe-Mg carbonate. Approximately 96% of the gold is free. The veins contain around 3% sulphides (arsenopyrite, pyrite, pyrrhotite, loellingite, chalcopyrite, bismithunite, sphalerite, galena, molybdenite, tetradymite, maldonite and a variety of Bi-Pb-Ag sulphosalts.

The Pogo Mine is an underground cut-and-fill operation using gravity, flotation, and cyanide leaching processes to recover gold.

Pogo is an underground mine with a vast network of more than 90 miles of underground roads winding to depths more than 1,000 feet below the surface. Ore is drilled, blasted, loaded onto underground haul trucks and delivered to an underground ore bin. From there, the ore is transported along a 2,500-foot-long conveyor belt to the surface ore bin.

The onsite mill processes up to 3,500 tons of ore daily. Gold is recovered using several unit operations.

Once the ore is delivered to the mill, the grinding circuit reduces the ore to a very fine particle size (about half of the size of a grain of table salt). This is the first step in separating the gold from the rest of the rock.

GRAVITY: Approximately 1/4th of the gold is recovered using gravity methods. Imagine a really big sluice box or gold pan.

FLOTATION: The remaining gold and sulfides are concentrated through flotation. The flotation concentrate is then reground to a powder consistency to expose the finer gold particles.

LEACH CIRCUIT: The exposed gold is extracted using chemistry that makes the gold particles go into solution.

CARBON-IN-PULP: The Carbon-in-Pulp (CIP) process pulls the gold in solution out of the slurry and loads it onto small pieces of carbon. The carbon is then stripped of the gold using a combination of reagents, heat and pressure. Following the CIP, the slurry is detoxified and placed underground as paste backfill to fill the void created during mining.

ELECTROWINNING: The gold in solution is electrodeposited as gold sludge by electrowinning. The gold sludge is then smelted in an onsite induction furnace at temperatures above 2000* F and then poured into large gold bars weighing upwards of 50 pounds.

CYANIDE DESTRUCTION: All materials that have come into contact with cyanide undergo the INCO SO2 process (a chemical process) to destroy the cyanide.