The poly-metallic mineralization of the GC deposit belongs to the mesothermal vein infill style of deposit and exhibits the following characteristics:

• The mineralization occurs as veins which are structurally controlled within broader alteration zones. The alteration can reach more than a few metres along the faults distributing in both hangingwall and footwall.
• The veins have a sharp contact with the host rocks and steeply dip at angles between 60 – 85°.

In general, the Ag-Zn-Pb mineralization occurs along the strike of the faults. The veins have true widths varying from just over 0.1 m to over 10 m. They have been traced for over 1,250 m along strike, and approximately 550 m down dip.

Ag-Zn-Pb mineralization at the GC deposit can be divided into two types: primary and oxidized. The primary mineralization is mainly composed of galena-sphalerite-silver minerals which occur sparsely, as disseminations, veinlets and lumps. Primary mineralization accounts for 95% of the entire Mineral Resource. Oxide mineralization occurs on and near the surface.

Mineralized veins in the GC area occur in relatively permeable fault-breccia zones. These zones are extensively oxidized from the surface to depths of about 40 m. Veins in this zone exhibit open space and boxwork lattice textures resulting from the leaching and oxidation of sulphide minerals. Secondary minerals present in varying amounts in this zone include kaolinite, hematite, and l ........

Mining has been conducted in two stages that are horizontally defined by mine sections and vertically by elevations, with a general description as follows:
1 Stage 1: +150 mRL to -50 mRL between local Mine Sections 10 to 36 for development and 12 to 32 for production - west side of project.
2 Stage 2: +100 mRL to -50 mRL between Mine Sections 36 to 54 for development and 32 to 54 for production. From -50 m RL to -300 mRL between Mine Sections 12 to 50 for both development and production.

Stage 1 essentially targeted bringing the project into production as soon as practicable using mobile rubber-tired diesel-powered equipment (development jumbo, loader, and truck) with surface declines access down to -50 mRL.

Stage 2 development from -50 mRL down to -300 mRL employs conventional tracked equipment (battery powered locomotives, rail cars, electric rocker shovels and pneumatic handheld drills) via a surface shaft access.

Selective stoping methods - shrinkage and resuing - are employed with stope production drilling conducted with pneumatic jackleg drilling. In-stope rock movement is by gravity to draw points or hand-carting to steel-lined passes.

Stage 1 production mucking used load-haul-dump loaders (LHD) with trucks hauling ore to the surface ROM stockpile, and ore was re-handled from the ROM stockpile to the primary crusher feed bin using a ROM front-end-loader (FEL).

Stage 2 and ongoing product ........

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The overall process consists of crushing, grinding, sequential flotation of lead, zinc, and pyrite concentrates, and concentrate dewatering by disc filtration. An experimental tin recovery gravity separation circuit is installed on pyrite flotation tails.

Two-stage crushing is carried out, with the second stage in closed circuit. Run of mine ore at -350 mm is reduced to crusher product at -10 mm. This is followed by two-stage grinding in ball mills to a product size of 80% passing 75 µm (P80 of 75 µm).

The flotation process consists of a standard flotation of lead, with three-stage cleaning of the lead concentrate, then flotation of zinc concentrate with three-stage cleaning; leaving pyrite tailings as S concentrate. Concentrates are dewatered by conventional thickening and filtration.

The experimental tin recovery circuit treats Zn scavenger flotation tailings. It comprises spiral classification, followed by coarse and fine gravity concentration using ........