Austar is located in the South Maitland Coalfield of the Maitland Group which forms part of the Newcastle Coalfields. The mid Permian Age Greta Coal Measures outcrop around the Lochinvar Anticline, which is the dominant structural feature in the Cessnock area. Austar Mine Complex is located on the nose of the Anticline. Coal in the Stage 2 Extension Area will be sourced from the Greta Seam at depths of approximately 530 to 560 metres below the
surface.

The Greta Seam is overlain by the Branxton Formation, which comprises a series of interbedded sandstone and siltstone layers up to 20 metres thick. The Pelton Seam, which is less than 0.5 metres thick, lies at the top of the Branxton Formation and forms the upper limit of the Greta Coal Measures.

The Austar Coal resource covers a large area of the Greta Seam in the Newcastle Coalfield. The Bellbird South reserves are situated north-east of and adjoin the original Ellalong Colliery.

Longwall panel A2 in the Stage 1 mining area was completed in November 2008, with production in Stage 2 (A3-A5a) beginning in February 2009. Longwall A3 was completed in March 2010. Longwall A4 was the only longwall extracted during the AEMR period and was completed in May 2011. The completion of the Stage 1 mining activities and the combined A3 and A4 mining in Stage 2 has supported predicted subsidence levels developed by MSEC, in that actual total subsidence was equal to or less than maximum predicted levels (and much lower than upper bound predictions).

All ROM coal from the underground is transferred by conveyors via the Ellalong Drift to a 2000 tonne bin at Pit Top, where an overland conveyor system with a nominal capacity of 900 tonnes per hour conveyors the coal to the Pelton CHPP raw coal stockpile. The majority of product coal processed at the CHPP is railed to the Port of Newcastle via the Austar Rail Line, the South Maitland Railway and the Main Northern Rail Line.

The CHPP is a heavy medium (HM) plant. There are three circuits that treat different
fractions:
- No.1 HM circuit treats the -12mm x 1mm coal; and
- No.2 HM circuit treats the - 45mm x 12mm coal.
- Fines circuit treats the -1mm fraction (spirals and cyclones) Coal enters the plant and passes over a set of sizing screens. Oversize material (+120mm) is removed from the plant as refuse and the fines (-1mm coal) are treated in the fine coal circuit.