Dorstfontein complex is on the northern margin of the Highveld Coalfield between the towns of EMalahleni in the north and Bethal in the south. Dorstfontein complex is on the Smithfield ridge, the boundary between the Highveld and Witbank Coalfields. Basement rocks in the area comprise pre-Karoo rocks, i.e. Transvaal supergroup, the Waterberg group, and intrusives of the Bushveld igneous complex. These are overlain unconformably by diamictites and associated glaciogenic sediments of the Dwyka group of the Karoo supergroup. Dwyka rocks are overlain by sediments of the Vryheid formation of the Ecca group. Coal seams in the area are hosted in the Vryheid formation which ranges in thickness from 80m to 300m.

Five major coal seams are present in the area, named from the base upwards, no 1 seam (S1), no 2 seam (S2 subdivided into S2L and S2U), no 3 seam (S3), no 4 seam (S4 subdivided into S4L and S4U) and no 5 seam (S5).

Numerous Jurassic dolerites (dykes and sills) intruded the Vryheid formation at various stratigraphic levels in the area. These intrusions tend to negatively influence stratigraphy and coal qualities in places. The distribution of the lower coal seams is strongly influenced by basement topography, while the distribution of the upper seams is controlled by present-day topography. Seams often thin and sometimes pinch out over and against palaeo-highs.

Dorstfontein complex, illustrated below, lies just north of the town of Kriel, in Mpumalanga, South Africa. The complex comprises the underground Dorstfontein West (DCMW) operation and open-cast Dorstfontein East (DCME) mine.

Opencast techniques are currently employed to mine the DCM reserves. The remainder of the deeper reserves will be mined by conventional mechanised underground bord and pillar mining method. Opencast mining activities currently targets the No. 2 and 4 seam lower reserves, however all seams thicker than 0.5 m are considered during mining operations.