Underground operations at Mt Morgans are sourced from the Westralia mine area which comprises the Beresford and Allanson deposits. The deposits are ~15km from the Mt Morgans treatment plant.
The deposits occur over a horizontal strike distance of 2.8km and lies within 700m of the surface. Previous mining and on-site treatment of the deposit has demonstrated that the gold is free milling with recoveries of 91%-93% achieved historically from conventional site-based CIP/CIL processing.
The gold at Westralia occurs within a banded iron formation (BIF) unit from which approximately 900,000 ounces at 4.5 g/t gold was produced up to 1998; with the majority being sourced from the Westralia open pit and historic underground workings.
Underground mining at Westralia is by Long-Hole Stoping methods (LHS), retreating to three separate declines – two at Beresford and one at Allanson.