The Muswellbrook mine sits within the Permian aged sediments of the Greta Coal Measures in the Hunter Coal Field.
The coal measures within the region form part of the Muswellbrook Anticline, which is truncated to the east by the Aberdeen Thrust. The Muswellbrook Anticline causes the Greta Coal Measures to be exposed at Muswellbrook. The Aberdeen Thrust is exposed in the highwall of the No. 2 Open Cut.
Existing operations target the Fleming, Hallet, Muswellbrook, St Helliers, Lewis and Loader seams. These seams range in thickness from 1m to 9.5m and dip to the north.
