CGO is located in the Achaean Murchison Province, a granite-greenstone terrane in the northwest of the Yilgarn Craton. Greenstone belts trending north-northeast are separated by granite-gneiss domes, with smaller granite plutons also present within or on the margins of the belts.

Mineralisation at Big Bell is hosted in the shear zone (Mine Sequence) and is associated with the post-peak metamorphic retrograde assemblages. Stibnite, native antimony and trace arsenopyrite are disseminated through the K-feldspar-rich lode schist. These are intergrown with pyrite and pyrrhotite and chalcopyrite. Mineralisation outside the typical Big Bell host rocks (KPSH), for example 1,600N and Shocker, also display a very strong W-As-Sb geochemical halo.

Numerous gold deposits occur within the Cuddingwarra Project area, the majority of which are hosted within the central mafic-ultramafic ± felsic porphyry sequence. Within this broad framework, mineralisation is shown to be spatially controlled by competency contrasts across, and flexures along, layer-parallel D2 shear zones, and is maximised when transected by corridors of northeast striking D3 faults and fractures.

The Great Fingall Dolerite hosts the majority gold mineralisation within the portion of the greenstone belt proximal to Cue (The Day Dawn Project Area). Unit AGF3 is the most brittle of all the five units and this characteristic is responsible for its role as the most favourable lithological host to ........

In FY22, the Tuckabianna plant received underground ore from the large Big Bell underground and the smaller Comet underground mine as well ore from the Cuddingwarra open pits.

While Big Bell was the primary producer of ore to the Tuckabianna mill, the Comet underground mine provided supplementary feed during the year.

After four years of dewatering, mine rehabilitation, refurbishment and ramp up, the Big Bell mine achieved commercial production in April 2022 and production rates have been growing since.

Several open pits were mined around Cue in FY22. With large stockpiles accumulated, the open pit program ceased at the end of the financial year.

Exploration and viability studies were carried out during FY22 at the previously mined Fender open pit mine on the southern limits of the Big Bell shear to evaluate the economics of an underground operation. An exploration decline was commenced then paused due with the higher tonnages coming from Big Bell.


Open Pit
A majority of the open pits have a final design wall angle of 39-46 degrees. Dilution of the ore through the mining process has been accounted for within the Ore Reserve quoted inventory. Various dilution ratios are used to represent the style of mineralisation. Minimum mining widths have been accounted for in the designs, with the utilisation of 40t or 90t trucking parameters depending upon the size of the pit excavation.

Underground
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CGO (Cue Gold Operations) incorporates the 1.2-1.4 Mtpa Tuckabianna processing hub.

CGO has an existing conventional CIL processing plant.

Gold extraction is achieved using two staged crushing, ball milling with gravity concentration and Carbon in Leach.

A high portion of the Reserve mill feed have extensive data when processed at other plants in the past 2-3 decades. This long history of processing demonstrates the appropriateness of the process to the styles of mineralisation considered.

No deleterious elements are considered, as a long history of processing has shown this to be not a material concern.