Mining takes place in a structurally complex zone between two major north-south trending faults the De Bron/Homestead Fault in the west and the Saaiplaas Fault in the east. The ore body has been subjected to severe deformation and contains numerous folds (anticlines and synclines) as well as an abundance of smaller faults.

The dip of the reef bands is very variable from 45 degrees to the east, adjacent the western side of the lease, to less than 2 degrees in parts of the southern area.

Production is hosted within two quartz pebble conglomerate bodies, developed above unconformity surfaces, termed reefs. These two reefs are known as the Basal and “B” reefs. Approximately 80% of the centares (1 centare = 1 square metre) are from the Basal Reef horizon and 20% from the “B” Reef horizon.

The Masimong complex comprises an operating shaft (5 shaft), and a second shaft (4 shaft), which, although closed for mining, is used for ventilation, pumping and as a second outlet. Masimong exploits the Basal Reef and the B Reef. Mining is conducted to a depth of 2 050m.

Masimong mines at moderate depths of between 1 650m and 2 010m below surface. The reef horizon is accessed by means of conventional grid development. The economic reef horizons extracted are the Basal Reef and the B Reef. Basal Reef accounts for approximately 80% of the on-reef production profile, and is mined on open and undercut operations, depending on whether the reef is overlain by shale. B Reef mining makes up the remaining 20% of the on reef production profile. It is located approximately 120m stratigraphically above the Basal Reef, thus necessitating separate infrastructure (i.e. footwall development). The presence of the upper shale marker approximately 20m thick below the B Reef strains the development rates of the B Reef, requiring drop raising to be done to effect holing on all box holes. Also all on-reef development needs to be done by means of wide raising. Despite the marginality of the ore body and the current economic environment, reserves on the mine give a life expectancy of four years, mainly due to the successful opening of known value trend extensions.

Ore mined is processed at the Harmony One plant.