The Bannockburn deposit is located along the western margin within the central portion of the Norseman-Wiluna greenstone belt. Locally the project area is dominated by an extensive sequence of tholeiitic, high-Mg and komatiitic basalts with intercalated sedimentary and intermediate volcaniclastic horizons. Dolerite and gabbro sills intrude the sequence. The deposit is complex with multiple controlling factors. The gross geometry of the deposit is controlled by the Bannockburn fault, a steeply dipping NNW trending fault that is continuous over at least 2.3km on the western margin of the orebody. The fault separates an ultramafic unit in the west from the Bannockburn host sequence in the east. It dips steeply east, rolling to vertical and steep west dipping in the northern part of the orebody. The Bannockburn fault is effectively the western boundary to the orebody with very little mineralisation penetrating the western side of the fault. The Central fault which hosts the Central orebody has a shallow northerly plunge and is the orebody on which the majority of the underground workings is focused. There are a series of steeply east dipping lodes in the hangingwall of the central lode; these are interpreted as either tensional veins of reverse faults with shearing present along the veins. Black graphic shale units present within the stratigraphy have acted as a localised control on the mineralisation. The black shale units have taken up some of the deformation with stratigraphy parallel shearing and mafic sequences between the shales have extended to form steep east dipping extension veins.

The Bannockburn gold deposit has a strike of 340° (NNW) and has a shallow plunge 5-10° to the NNW. The Bannockburn Shear dips steeply to the east, whilst the Central thrust varies from 30°dip to the west and east but is predominantly flat.

The Bannockburn deposit is amenable to mining by both open pit and underground methods. The deposit has been mined by open pit and underground methods historically. There are reasonable grounds to assume that in the future this deposit will again be mined by conventional open pit load and haul operations.

Mining Method The mining method to be employed at Bannockburn deposit is conventional open pit mining with a hydraulic excavator, dump truck fleet, and drill and blast activity.

Bannockburn reserve pit is designed as a large pit and will be mined in several stages to improve the stripping ratio. The Reserve pit will be mined such that it meets the operation efficiency, safety and production rate.

Single stage crushing:
- SAG and ball mill grinding circuit.

Thunderbox mill to be expanded to 3.5Mtpa during FY22. The secondary crushing circuit will deliver a finer product size to the grinding circuit. Saracen has purchased two Sandvik crushers that will be utilised (currently in storage).

It is expected that any future mining of the Bannockburn deposit will be processed at the Thunderbox processing facility.

The Thunderbox mill employs a conventional crushing, grinding and CIL leaching process to extract the gold. The mill operated successfully between 2002 and 2007, processing in excess of 9Mt of ore. The conventional plant displayed excellent performance with gold recoveries between 93.4 to 96.6 % over the life of the mine. It has since been upgraded to include a gravity recovery circuit facilitating continued high recoveries with increased throughput rates. Ongoing supply of Thunderbox ore to the processing facility will continue to be sourced from a combination of open pit oxide and fresh rock from the underground operations.