The VR is the principal economic horizon at Moab Khotsong and the C Reef is the secondary economic horizon and contributes less than 5% of the mining. Both reefs are narrow tabular deposits forming part of the Witwatersrand Supergroup and are stratigraphically located near the middle of the Central Rand Group. The Vaal Reef lies approximately 255m below the C Reef.

The geology at Moab Khotsong is structurally complex with large fault-loss areas between the three predominant mining areas (Top mine, Middle mine and Zaaiplaats). The geological setting is one of crustal extension, dominated by major south-dipping fault systems with north-dipping Zuiping faults sandwiched between them. The De Hoek and Buffels East faults structurally bound the reef blocks of the Middle mine to the north west and south-east respectively and the northern boundary is a north-dipping Zuiping fault. Extensive drilling is taking place on the extremities of Middle mine targeting potential preserved blocks. Close infill drill spacing is required to delineate the structural definition between the major structures to optimise the mine design and extraction of the orebody.

The VR consists of a thin basal conglomerate (the C-Facies) and a thicker sequence of upper conglomerates (the A-Facies). These two sedimentary facies are separated by the B-Facies, which is a layer of barren orthoquartzite. The A Facies is the principal economic horizon at Moab Khotsong, but remnants of the C-Facies are sporadically preserved below the A-Facies. High gold values in the VR are often located at the base of this unit and are associated with high uranium values as well as with the presence of carbon. Uranium is an important by-product.

The C Reef is mined on a limited scale, in the central part of Top mine where a high-grade, north-south orientated sedimentary channel, containing two economic horizons, has been exposed. To the east and the west of this channel, the C Reef is poorly developed with relatively small areas of economic interest. As with the VR, high uranium values are also often associated with high gold values and the presence of a 5mm to 2cm thick carbon seam at the base of the conglomerate. To the north of the mine, the C Reef sub-crops against the Gold Estates Conglomerate Formation and, in the extreme south of the mine, the C Reef has been eliminated by a deep Kimberley erosion channel and the Jersey fault.

The tabular nature, along with the depth and structural complexity of the orebody dictates the mining method utilised at Moab Khotsong mine. Mining at Moab Khotsong is based on a scattered mining method together with an integrated backfill support system that incorporates bracket pillars. The economic horizons are exploited between 1,791m and 3,052m below surface.

Moab Khotsong’s mineral processing is done through the Great Noligwa gold plant with design capacity exceeding the maximum planned production volume from the operation. The plant uses the reverse gold leach method which recovers gold and uranium through gold cyanide and acid uranium leaching.

The operation has a dedicated ore processing plant within close proximity to Moab Khotsong and tailings are pumped to existing tailings storage facilities. Most of the waste rock is separated from reef ore underground and accounted for separately. All waste and reef is delivered to the metallurgical plant. [MINERAL RESOURCES AND MINERAL RESERVES 2019. P.65]

The uranium plant residue at pH 1.5 -2.5 is returned to the gold plant where it is neutralised with lime in the neutralisation section. The pH neutralisation occurs in stages to pH 7.5, pH 9.5 and final pH 10.5 respectively in air agitated pachucas. The neutralised slurry at pH 10.5 is pumped to the leach section for cyani ........