The mineralisation at Barberton Mines is classified as Achaean epigenetic hydrothermal lode gold deposits within a granite greenstone terrain. The distribution and localisation of these orebodies in the BGB can be largely attributed to the combined influence of thermal metamorphism and structural deformation. The BGB has produced approximately 11Moz of gold since the first discovery in the early 1880s. Barberton Mines has produced more than 75% of the total production from the BGB.

Mineralisation at Barberton Mines is typically continuous in the short- to medium-range on strike with long-range geological and grade continuity being experienced down-dip. Gold occurs in either vein-hosted ore lode deposits or as free milling gold associated with fine grade sulphides, mainly pyrite and arsenopyrite.

The Barberton ores are thus mineralised shears with gold occluded in sulphide minerals. The sulphides often occur as massive assemblages in the shear structure. Lower grade ore, in the wall rock, form as a result of the alteration process during fluid flow and is associated with disseminated sulphide minerals. A late stage of gold mineralisation occurred in brittle fractures with the formation of quartz veins. These quartz veins often contain free gold in visible clusters.

Fairview Mine
The Fairview Mine orebody is an epigenetic hydrothermal lode gold deposit. Three distinct types of mineralisation occur at the mine:
• Refractory sulphidic ore, which constitutes the bulk of the mined ore, is hosted in the greywacke and shale sequence of the Fig Tree Group. The mineralisation is found in close association with an anastomosing shear system that often parallels the stratigraphy and lithological contacts. Auriferous pyrite and arsenopyrite mineralisation are confined to ribbon-like shoots within the shear system and as disseminations in the wall rock. The shears are often defined by quartz-carbonate veining and the host rock can be sericitised and carbonatised on either side of the shear.

• A coarse clastic unit of the Fig Tree Group hosts a series of hanging wall bodies. This coarse clastic unit consists of thick-bedded to massive greywacke, grading into arenite with interbedded granule stone layers. Two quartz-porphyry dykes and two dolerite dykes intrude the host rock sediments. Although the mineralised fractures persist for up to 500m, payable gold values are confined to several discrete ribbon-like payshoots. Blue-black quartz veins, quartz-carbonate veins and stockworks are recognised in the hanging wall area.

• Quartz veins, containing free-milling gold, occur in the Moodies Group in the footwall of the Sheba Fault. The blue-grey quartz veins fill near-vertical cross-cutting fractures in the siliceous, brittle quartzite units. Gold mineralisation generally occurs within the vein, but may penetrate the adjacent host rock. Only minor pyrite and arsenopyrite are associated with this ore type.

Sheba Mine
The Sheba orebody is an epigenetic hydrothermal lode gold deposit. Three distinct types of mineralisation occur at the mine:
• Refractory sulphidic ore (MRC section), which constitutes the bulk of the mined ore, is hosted in the greywacke and shale sequence of the Fig Tree Group. The mineralisation is found in close association with a shear system in the immediate hanging wall of greenschist anticlines of the Zwartkoppie Formation. Auriferous pyrite and arsenopyrite mineralisation occurs as massive replacement veins within the shear system and as disseminations in the wall rock.
• The ZK section is characterised by the occurrence of visible gold and disseminated pyrite in the greenschist as the prominent mineralisation, in association with shear and fracture-hosted smoky and white quartz veins.
• The mineralisation of the Royal Sheba orebody is encapsulated in a shear envelope of the Sheba Fault, ranging in width from 5m to 25m. The gold mineralisation occurs predominantly in sulphide minerals and as native gold.

The New Consort orebody is an epigenetic hydrothermal lode gold deposit. Gold mineralisation at the New Consort section is associated with the contact between the underlying schist of the Onverwacht Group and the overlying metapelite of the Fig Tree Group. This contact is marked by the presence of the Consort ‘bar’, a highly siliceous banded chert. The Consort Bar is thought to be a silicified mylonite occupying the contact. A series of north-dipping tabular pegmatites, termed the Muiden Reef pegmatites, displace the south-dipping Consort contact and the mineralised shoots. Some scheelite mineralisation has been recorded, associated with the pegmatites.

Barberton Mines comprises Fairview Mine, Sheba Mine and New Consort Mine.

Fairview Mine is an underground complex consisting of adits and sub-decline shaft systems.The mining operations is carried out using semi-mechanised up-dip cut-and-fill mining method. Gold rich orebodies are mined from near surface to approximately 1.7km below surface at the 11-block MRC orebody. Ore is transported through three decline shaft systems to 11 Level. From here, the ore is crushed and transported via an aerial bucket system to the Fairview metallurgical plant.

New Consort Mine is an underground complex consisting of adits and subvertical shaft systems. The mining operations is carried out using up-dip cut-and-fill mining method. Ore is extracted mainly from the MMR, PC and 3 Shaft sections, located 200m to 1.5km below surface. The ore is transported through the shaft system to the New Consort metallurgical plant.

Sheba Mine is an underground complex consisting of adits and subvertical shaft systems. The mining operations are carried out using up-dip cut-and-fill and long hole open stoping mining methods. Ore is mined from near surface from the MRC, Sheba West and Thomas orebodies to approximately 1.2km below surface in the Zwartkoppie (ZK) orebody. The ore is transported through the shaft system to the Sheba metallurgical plant.

Fairview metallurgical plant.
Fairview metallurgical plant consists of a milling, gravity gold separation, flotation, BIOX® and carbon-in-pulp (CIP) circuit with a carbon regeneration section, elution (and electro-winning) circuit and smelt house. The Fairview plant capacity is 13.5ktpm.

New Consort metallurgical plant.
Ore from New Consort Mine is crushed, milled, gravity gold concentrated and floated. The float concentrate is transported to the Fairview BIOX® section for further processing, while the tails are subjected to the New Consort carbonin-leach (CIL) circuit. The loaded carbon from the CIL section is transported to Fairview for elution (and electro-winning). The total capacity of the New Consort metallurgical plant is 8ktpm.

Sheba metallurgical plant.
Ore from Sheba mine is crushed and milled, gravity separated and floated. The gravity concentrate is smelted in the Fairview smelt house. Flotation concentrate is transported to the Fairview ........