Pan African Resources' subsidiary, Barberton Mines Proprietary Limited, owns 95% of the Barberton operation. Employees own 5% of the issued share capital of Barberton Mines through an ESOP.
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Summary:
Barberton Mines comprises Fairview Mine, Sheba Mine, New Consort Mine and the BTRP.
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, forms 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.
BTRP is a deposition material of historically treated metallurgical tailings from the Fairview, New Consort and Sheba Mines. The material is confined to the deposition site of historical tailings and approximately 1m beneath the historical footprint. The ore consists of oxidised tailings containing pyrite and arsenopyrite associated gold, which was not recovered in the initial treatment process.
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. The contacts and texture of the veins suggest a dilation fracture fill origin, rather than replacement origin.
Refractory gold-quartz-carbonate-sulphide ore occurs as disseminated to massive pyrite and arsenopyrite mineralisation. The age relationship between the gold mineralisation and the quartz-porphyry dykes suggests that the Hope Reef is marginally older and the Le Roux Reef is marginally younger than the quartz-porphyry dykes.
• 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.
The deepest intersection on a Fairview orebody is at a depth of 1,660m below the adit elevation, approximately 100m below the current mining platforms. The orebody is open at depth.
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 deepest orebody intersection on Sheba Mine is 1,200m below shaft collar elevation. The orebody is open at depth.
Consort
The Consort area can be divided into two distinctive synclinal structures, termed the Three Shaft Syncline and the Top Section Syncline. The Shires structure, which is a prominent north-south striking shear zone separating these two synclines, is intruded by pegmatites.
The Consort orebody is an epigenetic hydrothermal lode gold deposit. Gold mineralisation at the 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 layer. 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, which is associated with the pegmatites.
A lenticular body of fine-grained siliceous amphibolite, termed the ‘footwall lens’, occurs on the northern limb of the Top Section Syncline and is host to the mineralisation in the PC and MMR shoots. Mineralisation consists of arsenopyrite and visible gold associated with fractures in the footwall lens. The Consort Bar is host to mineralisation in the 7 Shaft, 3 Shaft and Ivaura areas.
The deepest intersection of the Consort orebody is 1,450m below adit elevation. The orebody is open at depth.
BTRP
The BTRP operation re-treats previously processed gold ore in the form of slime or tailings material. The slimes emanated mostly from historical mining and processing activities of the same orebodies that are currently being mined underground from the existing Barberton Mines operations.