The coal measures of the North Block Complex occur on the eastern edge of the Witbank coalfield, within the Permian-age Vryheid formation of the Ecca Group in the Karoo Sequence. The Witbank coalfield is situated in the northern part of the Main Karoo basin and extends about 190km west-east between Brakpan and Belfast and about 60km north-south between Middelburg and Ermelo.

The main Karoo Basin:
- Was filled between the Late Carboniferous and Middle Jurassic periods;
- It is lithostratigraphically subdivided into the Dwyka, Ecca and Beaufort Groups, succeeded by the Molteno, Elliot and Clarens Formations and the Drakensburg Formation (volcanics);
- The coal bearing Ecca Group has been divided into three sub-units: the Pietermaritzburg; Vryheid and Volksrust Formations.

The Witbank Coalfield:
- The coal-bearing Vryheid Formation attains a thickness of 70m to 200m in the Witbank Coalfield;
- Here the Vryheid Formation consists of five coarsening-upward sequences with coal seams associated predominantly with the coarser grained fluvial facies at the top of each sequence;
- The No. 5, 4, 2 and 1 coal seams are of economic interest.

NBC (Glisa) mine resource area is close to the eastern edge of the Witbank Coalfield, in the northern part of the main Karoo basin. All Witbank Coalfield seams, i.e. S1, S2, S3, S4 and S5, occur in the Glisa area, with S2, S3 and S4 being economically important. Stratigraphy consists predominantly of the different coal seams separated by fine and medium to coarse grained sandstone, with subordinate mudstone, shale, sandstone and carbonaceous shale.

The thickness of the coal seam ranges from 0,5m to 3,1m, averaging 2,3m. The coal seam is overlain by medium to fine-grained sandstone with shaly bands. On top of the whole succession is overburden material comprising sandy soil and regolith. The average total depth to coal is relatively shallow at 10,7m and the maximum depth to top of coal is around 17,8m.

The primary operation is the Glisa mine, a multi seam open-cast mining operation 5km west of Belfast in the Highveld region of Mpumalanga.

The Eerstelingsfontein block to the south-east of Glisa comprises gently sloping topography. The coal resource here is contained in a single seam, S2. This seam occurs as an erosional remnant on high ground at shallow depths, suitable for open-cast mining.

The North Block Complex infrastructure consists of a Dense Medium Separation coal beneficiation plant and four crushing and screening plants (two of which will be transferred to NBC and two of which are owned and operated under long-term contracts), a water treatment facility and a rail siding that provides direct access to the Richards Bay Coal Terminal.

Water treatment plant 1.8 mega litres/day currently treating 1.2 mega litres producing water of potable quality.