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.

On 26 February 2021, after over 100 years of operation, the decision was made to transition Austar Coal Mine to closure activities. No mining was undertaken during the 2020 – 2021 reporting period. Austar mine is ventilated by two upcast (exhausting) shafts being No.3 Shaft and No.5 Shaft. Both shafts are continuously monitored for both flow and gas concentrations. As Austar transitions to closure it is planned No. 5 Shaft will be become redundant and be turned off in approximately Q2 2022 and No.3 Shaft with be turned off late Q4 2022 or early Q1 2023.

As Austar is transitioning to closure, during the 2020 – 2021 reporting period no coal was mined at Austar or processed at the Austar CHPP. PLANT Once mined, coal was sent to the Coal Handling and Preparation Plant for crushing and washing to produce a high quality coking coal product for export. Coal has been processed using a combination of dense medium cyclones and spiral techniques.