Beatrix is a deep level underground gold mine located along the northern and southwestern margins of the Witwatersrand Basin in South Africa. This mine is typical of the many Witwatersrand Basin operations, which have been the primary contributors to South Africa’s production of a significant portion of the world’s recorded gold output since 1886.

The orebodies at Beatrix are laterally continuous with relatively long-range predictability. This lends to clear patterns of mineralisation governed by sedimentary characteristics.

The Beatrix Reef (BR) was originally exploited as the main orebody, but has since changed, with the main production coming from the VS5 (Elsburg Formation), the Aandenk (AAR) and Kalkoenkrans (KKR) Composite Reefs.

In general, the Composite VS5/AAR Reefs ranges between 130cm and 350cm in width. The orebody is shallow dipping at 10º – 15º, with typical open fold structures. In most cases the reefs are deemed to be bottom loaded, with most of the gold grade concentrated along the basal contact.

The Witwatersrand Basin comprises a 6,000-meter vertical thickness of sedimentary rocks, extending laterally for some 350 kilometres northeast to southwest by some 120 kilometres northwest to southeast, generally dipping at shallow angles toward the centre of the Witwatersrand Basin. The Witwatersrand Basin outcrops at its northern extent near Johannesburg, but to the west, south and east it is overlaid by up to 4,000 meters of volcanic and sedimentary rocks. The Witwatersrand Basin is Archaean in age, meaning the sedimentary rocks are of the order of 2.8 billion years old.

Gold mineralisation occurs within laterally extensive quartz pebble conglomerate beds called reefs, which are developed above unconformable surfaces near the basin margin. As a result of faulting and primary controls on mineralisation processes, the goldfields are not continuous and are characterised by the presence or dominance of different reef units. The reefs are generally less than two meters in thickness and are widely considered to represent laterally extensive braided fluvial deposits or unconfined flow deposits, which formed along the flanks of alluvial fan systems around the edge of an inland sea. Dykes and sills of diabase or dolerite composition are developed within the Witwatersrand Basin and are associated with several intrusive and extrusive events.

Gold generally occurs in native form, often associated with pyrite, carbon and uranium. Pyrite and gold within the reefs display a variety of forms, some obviously indicative of detrital transport within the depositional system and others suggesting crystallisation within the reef itself.

As early as 1923, the presence of uranium was noted in the Witwatersrand reefs. It was found that on average the reefs contain about 0.03% uranium and as a by-product of gold relatively low uranium grades can be recovered. Notwithstanding different opinions as to the origin of the uranium in the reefs, most theories accept localisation of both gold and uranium a function of sedimentary textures. Metal concentrations are directly related to the reefs. Exploration programmes and eventual evaluation of gold and uranium according to a placer philosophy, prove to be highly successful.

The most fundamental controls of gold and uranium distribution are the primary sedimentary features such as facies variation and channel directions. Consequently, the modeling of sedimentary features within the reefs and the correlation of payable grades within certain facies is key to in situ reserve estimation, as well as effective operational mine planning and grade control.

Beatrix has three vertical shaft complexes (one sub-shaft) and two mineral processing plants. Supporting infrastructure to service the operating shaft sections is also in place:
• South Section (1 Shaft) – operational
• North Section (3 Shaft) – operational
• West Section (4 Shaft) – operational

Mining method:
• Conventional breast mining (virgin areas) – 99%
• Conventional breast mining (remnants and pillar extraction) – 1%

Beatrix is principally an underground mine with nominal surface reserves represented by surface rock dumps (SRDs) accumulated during the operating history of the mine.

Gold mining began at Beatrix in 1985 and at Oryx (Beatrix 4 Shaft, also known as West Section) in 1993.The existing scope of operations is the result of the consolidation of the adjacent Beatrix and Oryx mines on 1 July 2002. Beatrix has three operating shaft systems with two ventilation shafts to provide additional upcast and downcast ventilation capacity.

Beatrix, a shallow to intermediate-depth operation, mining at depths of between 700m and 2,200m below surface, exploits the Beatrix Reef at shafts 1 and 3, and the Kalkoenkrans Reef at 4 Shaft.

Beatrix is serviced by two metallurgical plants. Processing occurs by way of carbon in leach (CIL) and carbon in pulp (CIP) treatment at the No 1 and 2 plants respectively:
- Beatrix 1 plant – operational, 240 tpd design capacity;
- Beatrix 2 plant – under care and maintenance, 130 tpd design capacity.