The Fosterville Goldfield is located within the Bendigo Structural Zone in the Lachlan Fold Belt. The deposit is hosted by an interbedded turbidite sequence of sandstones, siltstones and shales. This sequence has been metamorphosed to sub-greenschist facies and folded into a set of upright, open to closed folds. Mineralization at Fosterville is controlled by late brittle faulting. These faults are generally steeply west-dipping reverse faults with a series of moderately west-dipping reverse splay faults formed in the footwall of the main fault. There are also moderately east-dipping faults which have become more significant footwall to the anticlinal offsets along the west dipping faults. Primary gold mineralization occurs as disseminated arsenopyrite and pyrite forming as a selvage to veins in a quartz-carbonate veinlet stockwork. The mineralization is structurally controlled with highgrade zones localized by the geometric relationship between bedding and faulting. Mineralized shoots are typically 4 to 15 metres thick, 50 to 150 metres up/down dip and 300 to 1,500 metres down plunge, and have average grades of 5 to 10 g/t gold, with individual assays up to 60 g/t gold. Primary gold at Fosterville also occurs as visible gold that variably overprints sulphide mineralization and is found as disseminated fine specks of gold within host quartz veins. The visible gold is spatially associated with antimony mineralization in the form of stibnite that occurs with quartz and varies from replacement and infill of earlier quartz-carbonate stockwork veins, to massive stibnite-only veins of up to 0.5 metres in width. The stibnite-quartz event occurs in favourable structural locations, such as the Phoenix, Eagle and Lower Phoenix structures. The occurrence of visible gold is becoming increasingly significant at depth and is observed more frequently below approximately 800 metres depth, down-plunge within the Lower Phoenix and Harrier gold systems. In the Lower Phoenix system, the high-grade Eagle Zone is 0.5 to 6 metre in width, 50 to 80 metres in dip length and has a down-plunge extent of 700 metres while the Swan Zone — currently the highest-grade mineralized zone at Fosterville — is 2 to 5 metres in width, dips west and is presently defined over a 275-metre strike and a 200-metre vertical extent. The Eagle and Swan zones remain open down-plunge for potential mineral-resource expansion.

Mining activities at Fosterville are currently focused on the Central, Phoenix and Harrier underground ore zones. All areas are extracted using open stoping techniques with the application of Cemented Rock Fill where practical. Selection of the specific mining method within the open stoping regime is based upon previous experience at the Fosterville mine and expectations of ore zone geometry and geotechnical conditions. In 2020, work on a twin exploration drive, capable of supporting production activities, commenced to connect the existing Fosterville mine to Robbin’s Hill, which is expected to be established as a second mining operation to feed the Fosterville mill over the next few years. The twin drive had advanced over 7,800 metres as at December 31, 2021 and remains on track for completion in mid-2022. Underground mining is conducted using a conventional fleet including jumbos, production drills, loaders, trucks and ancillary equipment. Open Cut mining (when required) is conducted using a conventional fleet including excavators and trucks with a contract mining fleet and workforce. The Phoenix to 4240mRL, Harrier below 4500mRL, Central and Robin orebodies are accessed from a footwall decline position while the Phoenix below 4240mRL and Harrier orebody above 4500mRL are accessed from the hangingwall. All areas are planned to be extracted using open stoping techniques, primarily in a top down sequence, with the application of cemented rock fill or paste fill where applicable and practical. Selection of the specific mining method and extraction sequence within the open stoping regime is based upon previous experience at the Fosterville mine and expectations of ore zone geometry and geotechnical conditions. A standard level interval of 20 vertical metres can be applied across all mining areas however, this can be and is varied as is required to maximize the extraction of the economic material. Underground mining is conducted using a conventional fleet of trackless diesel equipment including development jumbos, production drills, loaders, trucks and ancillary equipment. Production tonnage rates within the Phoenix and Harrier orebodies are expected to increase over the coming years as ventilation upgrades take effect and both areas open up through previous development and sequencing. With the addition of ore from the Robbin’s Hill orebody, peak production output within the life of mine plan is expected to increase to over 800,000 tonnes per annum.

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Since the commissioning of the processing plant in 2004, all processing models for the mill have been based on actual plant performances. The processing budget takes into consideration the mining schedule (ore source location, tonnes to be mined and gold grade), and predicted sulfur grades to be processed.

The process plant incorporates the following unit operations:
- Single stage crushing with a primary jaw crusher;
- Open stockpile with reclaim tunnel;
- 20ft diameter by 20ft length Semi-autogenous grinding (SAG) mill;
- A gravity circuit to recover coarse gold from the grinding circuit recirculating load;
- Flotation circuit to produce a gold bearing sulfide mineral concentrate and a barren residue;
- 8ft diameter by 13ft length flotation concentrate regrind mill;
- A gravity circuit to recover coarse gold from the flotation concentrate with gravity circuit concentrate being direct smelted;
- A Bio-oxidation circuit consisting of ........