Gold mineralisation at Cowal is most concentrated to a north-south orientated corridor hosted in second and third order structures marginal to and parallel to the Gilmore Suture. The gold deposits are hosted by a shallowing-upwards sequence of semi-conformable sedimentary, volcaniclastic, and volcanic rocks of trachydacitic and trachyandesitic composition that have been intruded by a diorite sill, andesite dome, and various dykes. The sequence strikes northeast–southwest and dips moderately 30° to 40° to the northwest.

The mineralisation at CGO comprises four deposits: E41, E42, E46 and GRE46.

The E41 West mineralisation strikes north-northeast and dips -70° east, and measures 750m along strike and 250m across strike. Individual mineralized zones are 35-50m wide and extend down dip for 125m. The E41 East mineralisation strikes east-west and dips -35° to -80° south, and measures 475m along strike and 500m across strike. Individual mineralized zones are 35-50m wide and extend down dip for 225m.

The GRE46 zone trends north-south, dips vertical to -70° west, and extends approximately 2km along strike, 200m across strike and at least 1km down dip. Individual lenses in the GRE46 mineralised zone are 1-15m wide, 25-250m long, and extend 50-200m down dip. Lenses consist of narrow high-grade quartz carbonate, pyrite and base metal veins controlled within a structural north-south corridor, broad zones of alteration around lithology contacts and occasional zones of grade enrichment occur in dilatant structures within the deposit known as Quartz Sulphide Breccias. Host lithology varies from poorly mineralised massive intrusive diorite and fine volcaniclastic sediments through to the preferential mineralised trachydacitic lava in the north, lenses of coarse to conglomeritic volcaniclastic sediments and the andesitic Dalwhinnie lava unit to the east. Lithological contacts with strong competency contrasts also provide broad areas of mineralisation. The trachydacite is brittle with common hyaloclastite and peperitic textures, commonly brecciated to peperitic and is both a good geochemical and rheological host for Au mineralisation.

Vein orientation at the GRE46 deposit displays a distinct change in orientation on a nominal northing of 37,000mN. Vein in the south of the deposit are generally orientated at 50°/120°. Veins in the north of the deposit rotate clockwise and steep to a general dip direction of 70°/180°. The E42 deposit trends north-south and dips -35° to -45° west. Four domains are separated by the Western, Central and Cowal faults. A further two lithological domains are comprised of the primitive outer rind of the Muddy Lake diorite and the fractionated Monzodiorite core Overall, the E42 Main Zone mineralisation is approximately 850 m by 850 m and extends 500m down dip. The E46 open pit mineralisation trends north-northeast, dips -40° west to flat lying, and measures approximately 650m along strike and 17m across strike. Individual zones are approximately 50m wide and extend 100 m down dip. Mineralisation is predominantly hosted in oxide material and is generally poor in primary lithologies.

Mining method assessments indicated that sub-level open stoping (SLOS) with pastefill was the most appropriate mining method for the GRE46 underground deposit. This ensured maximum extraction of the economic portion of the deposit, while ensuring no surface subsidence due to the deposit being under Lake Cowal.

Mineable stope shapes were created using the Mineable Shape Optimiser (MSO) software from Datamine, according to stope design parameters established in the PFS. Stope shapes were created using Au grade as the MSO optimisation field at an incremental cut-off grade.

Stope shapes were informed by geotechnical assessment to determine stable stope spans. The typical sublevel interval is 30m, strike length of 20m and stope width of up to 20m.

All stopes above the 1080 mRL have been excluded from the design to ensure the oxide boundary is not intersected, reducing the likelihood of surface subsidence.

An Equivalent Linear Overbreak Sloughing (ELOS) stope dilution of 0.2m footwall and 0.2m hangingwall was applied in the MSO shape parameters. A further 5% stope dilution has been applied in the schedule to account for any further dilution that may occur.

Ore drive development had no dilution applied to prevent overestimation of metal. Other development has a dilution factor of 10% applied.

Mining recoveries were set at 100% for development activities, and 95% for stoping activities.

All material mined underground will be trucked to surface to the Run of Mine (ROM) pad or waste dump.

As Cowal is an established mine site, all major infrastructure is already in place (i.e. processing plant, power, water, magazine etc.); modifications and/or expansions to these facilities are accounted for in the PFS. Provision for construction and operation of a pastefill plant has also been included.

The ore is to be processed through an existing flotation, CIP/CIL process plant with the inclusion of the newly built Float Tails Leach circuit. The current average Au recovery is 84%.

Geometallurgical testwork completed as part of the GRE46 Underground Pre-Feasibility Study (PFS) indicates an average Au recovery of 87%. This recovery factor has been applied to the underground ore in line with the FY21 LOM plan.

The following process plant modifications have been included in the GRE46 Underground PFS:

- a second primary jaw crusher dedicated to the treatment of underground ore. This crusher will remove tramp metal from the underground ore feed;

- an additional FTL elution circuit and carbon regeneration kiln;

- a deslimed tailings circuit located at the process plant's tailings area to supply tailings to the surface pastefill plant for operational backfill activities. Pastefill plant parameters have been based on an average production rate of 150m³/h.