The Afton deposits are copper-gold silica-saturated, alkalic porphyry-style deposits of a type that are found throughout British Columbia.

Copper-gold-silver mineralization occurs as disseminations and fracture-filling sulphide grains occurring in three roughly tabular east-west striking, steep dipping bodies. The Main Zone, as its name suggests, is the principal zone of mineralization. Present mining operations are located within the Main Zone. It is flanked to the east and south by two smaller bodies called the Hanging Wall Zones.

The mineralization at New Afton is grouped into three broad categories: hypogene, secondary hypogene, and supergene. The terms describing these zones date to the early days of exploration on the Project and are recognized now to be inaccurate. They have been retained, however, for consistency in order to minimize confusion. Hypogene was originally ascribed to primary copper sulphide mineralization that had not undergone significant oxidation. Presently, hypogene refers to chalcopyrite and accessory bornite mineralization which forms the core of the deposit and is dominated by biotite alteration. This is noted to typically occur along the northern margins of the monzonite stock in the Main Zone and discontinuous monzonite dykes in the HW Zones. For logging purposes, hypogene mineralization is defined as having greater than 1% sulphides, or 0.5% sulphides in bornitedominant zones.

Mesogene is used to describe a later overprint of secondary hypogene mineralization upon primary sulphide mineralization by tennantite-tetrahedrite with possible bornite and chalcocite. The secondary overprint is associated with bleached sericite-dolomite alteration localized along narrow fault zones and is responsible for the introduction of the deleterious elements arsenic, antimony, and mercury. It is thought to be related to late-stage, lower temperature low-pH fluids that ascended along high-angle structures and remobilized copper from primary sulphides to form sulphosalts and high-sulphidation state sulphide minerals. Secondary hypogene mineralization appears as sooty steel grey to bluish grey reaction rims on chalcopyrite blebs and stringer fractures. The distribution of mesogene mineralization is very narrow and discontinuous and commonly restricted to faults such as the HW, J, and D faults, particularly where they intersect. It is always associated with carbonate-rich phyllic alteration and only occurs where host structures intersect primary hypogene mineralization.

The supergene mineralization type has been assigned to oxidized portions of the deposit, where sulphide minerals have largely been replaced by native copper. The domain is roughly conical in shape and centred below the New Afton pit, limited to the east by the M fault. The supergene domain is defined for logging purposes as having 0.5% or greater native copper, or, in the absence of native copper, intervals of strong oxidation with a threshold assay of 0.2% Cu. Recent mapping by New Afton Mine geologists indicates the spatial distribution of supergene mineralization at the apex level of the block cave is also controlled by the E and K Faults.

The mineralized zone, as it is delineated to date, is a sub-vertically dipping, generally continuous, tabular body extending downwards from the base of the existing pit for approximately 1,250 m. The body plunges to the southwest at an angle of 50°, and extends 1,570 m from surface to the lowest drill hole intercept. The Main Zone measures approximately 220 m across strike at its widest point, and it tapers with depth and along strike. Two smaller satellite bodies are located on the hanging wall side of the Main Zone, bringing the maximum width of mineralization subtended by all bodies to just over 470 m.

New Afton is a block cave which utilizes a unique New Afton style undercut with an apex level and an undercut level. The apex level, located at the major apex of the pillars, provides a geographic window for bell and undercut blasting, and allows for post-blast inspection and assurance that undercut blasts are breaking over the major apex as designed.

The extraction level at New Afton employs straight-through drawpoints. This layout was favoured over the previously planned herring-bone layout primarily for geotechnical, ventilation, and access reasons, however, factors such as simplicity of design and rate of development were also considered.

Crushed ore from the underground mine is reclaimed from the surface stockpile by two 1.8 m × 11.0 m apron feeders located within the reclaim tunnel directly beneath the stockpile. The apron feeders discharge on to a 1.1 m wide conveyor belt which carries the ore into the mill grinding circuit.

The primary grinding circuit consists of an 8.3 m diameter × 4.0 m grinding length, 5,222 kW SAG mill in closed circuit with a single deck vibrating screen and a cone crusher. The cone crusher product discharges directly on to the mill feed conveyor, to be carried back into the SAG mill.

The secondary grinding circuit consists of a 5.5 m diameter x 9.8 m grinding length, 5,222 kW ball mill in a closed circuit with the grinding cyclopac. The SAG discharge screen undersize and ball mill discharge are pumped to the cyclopac, where the ore particles are classified by size. The cyclone underflow, containing the coarser ore particles distributes the slurry to the flash flotation cell, the primary gravity concentration circuit, and the ball mill. Both the SAG and ball mill circuit control is supported with an Expert control system.

The grinding cyclone overflow flows by gravity into the rougher flotation circuit, which consists of six 100 m3 flotation tank cells in series. The concentrate from the rougher flotation cells is collected in launders and flows by gravity to the regrind circuit; the tailings from the final rougher cell is discharged into the tailings pumpbox.

The regrind circuit grinds the rougher flotation concentrate, to decrease the particle size to 80% passing 35 µm to 40 µm, prior to it being processed in the cleaner flotation cells. The regrind circuit consists of a 932 kW Vertimill in closed circuit with the regrind cyclopac. The underflow stream from one of the operating regrind cyclones is processed through a XD-40 Knelson concentrator, to recover liberated gold from the regrind circuit. The Knelson concentrate discharges to the 3rd cleaner concentrate pumpbox, where it is pumped to the concentrate thickener. The Knelson concentrator tailings are discharged back to the regrind cyclone feed pumpbox. The regrind cyclone overflow discharges into the cleaner flotation circuit and the tailings flow to the cleaner scavenger flotation.

Concentrate is pumped to the thickener, where the solids achieve an underflow slurry density of approximately 55% solids. The slurry is pumped to an agitated tank and subsequently pumped into one of the two filter presses, where the concentrate is dewatered to less than 8% moisture. The dewatered concentrate is discharged from the filter presses directly into the concentrate storage shed, before being loaded onto trucks and transported to the Port of Vancouver for shipping.