Gwalia Deeps is an underground and open-pit mine, owned and operated by St Barbara Ltd. Gwalia Deeps is located in the Leonora Region of Western Australia, approximately 240 kilometers north of Kalgoorlie.

The processing plant is a conventional carbon-in-pulp (CIP) circuit and has a nominal capacity of 1.2 million tonnes per year of hard rock and up to 1.8 million tonnes per year, when softer material is blended. Other surface infrastructure includes a gas-fired power station, a paste-fill plant, and a refrigeration plant to cool the underground environment. Central to the mine ventilation system is a 5.5 meter ventilation shaft, which at 800 meters long is the largest raise bored shaft ever drilled in Australia.