The Cadia gold copper deposits are hosted by a late Ordovician to early Silurian shoshonitic volcano-intrusive complex which forms part of the larger zone of arc-related volcanic and associated intrusive rocks in the eastern Lachlan Fold Belt. Mineralisation at Cadia is hosted by the mid to late Ordovician Forest Reefs Volcanics and the underlying Weemalla Formation and by the late Ordovician early Silurian Cadia Intrusive Complex. Post-mineral cover comprises Silurian Cadia Coach Shale and a relatively thin capping of Tertiary basalts and gravels in some areas. Recognised structural controls include the regional northwest corridor – dilation zone thought to control the emplacement of the Cadia Intrusive Complex and post-mineral faulting in two dominant orientations striking northwest and north-south.

The Cadia East deposit is hosted within the Forest Reef Volcanics and porphyry intrusions. A north-east trending mass of narrow sheet like dykes of monzonitic to dioritic compositions intrude the lower parts of the FRV at Cadia East. These intrusives are largely restricted to the eastern half of the deposit although some narrow dykes and isolated bodies of monzonite have been recognised in the western end. At the upper western end of the deposit immediately underneath the Gibb Fault, isolated narrow intersections have been identified with south dipping mineralised quartz veining. These occurrences are interpreted to be the Cadia Hill Monzonite.

Mineralisation at Cadia East can be divided into two broad overlapping zones: an upper, copper rich disseminated zone and a deeper gold-rich zone associated with sheeted veins. The upper zone forms a relatively small cap to the overall mineralised envelope and has a core of disseminated chalcopyrite, capped by chalcopyrite-pyrite mineralisation. The upper zone mineralisation is stratigraphically controlled within the volcaniclastic unit. This zone is transitional to the deeper vein style mineralization. The deeper zone is localised around a core of steeply dipping sheeted quartz-calcite-bornite-chalcopyrite-molybdenite, with the highest gold grades associated with the bornitebearing veins. Copper and molybdenite form a mineralised blanket above and to the east of the higher-grade gold envelope.

The geology model for the Cadia East deposit includes lithology, alteration, and structural faults. Modelling of the fault planes and lithological boundaries comprises data obtained from drill core and underground mapping. The major faults are used as estimation domains, with semi-soft boundaries. The factor most influencing grade continuity is that Cadia East is a porphyry copper-gold mineralisation exhibiting properties of the diffusion model.

Mining studies and current underground cave mining activities at Cadia East support the appropriateness of the selected mining methods as the basis of the forward Ore Reserve estimate. Ongoing geotechnical studies and monitoring utilising experience and data from the current underground operations provide ongoing key direction for stability, design, and schedule sequence parameters.

Processing of the Cadia East underground ore stream will be through the Cadia Valley Operations Ore Treatment Plant Concentrators 1 & 2. Metal recovery is through gravity and conventional flotation to a copper/gold concentrate. This circuit processes Cadia East material with similarly styled material to future ore sources. Cadia East is the sole source of feed for both Concentrator 1 and Concentrator 2. Production of up to 36mtpa11 is anticipated to be produced through the concentrators. While the scale of the processing is expected to position the operation amongst the world’s largest gold mines, the technology associated with the ore processing is industry standard for this style of deposit and is already custom and in practice at Cadia Valley Operations.

An update to the process plant infrastructure and metallurgical recovery assumptions were completed during the Cadia Expansion Feasibility Study (2019) and Cadia Expansion Project - Stage 2 (2020) including propose ........