The Mitchells Flat project area is located in the Hunter Coalfield of New South Wales, about 15 kilometres northwest of Branxton and 12 kilometres east of Singleton. Plans for the development of an underground coal mine and associated infrastructure were approved in 1991 and a mining lease granted in 1993.

Mitchells Flat has Indicated Resources estimated to be 112 million tonnes, and Inferred Resources estimated to be 160 million tonnes. The mine will be able to produce steaming coal and soft coking coal.

The deposit lies within the Wittingham Coal Measures, part of the Upper Permian sediments of the Singleton Super-Group. It is structurally isolated from the remainder of the Hunter Valley measures by the Hunter Thrust to the north and east, and the West Brook fault to the west. It is a multi-seam deposit (8-10 coal seams) in a complex geological setting with potential open cut and underground resources.