The distribution of gold in igneous rocks and minerals is described and discussed. Not all the gold in igneous rocks is contained within early formed crystal lattices. Evidence that gold can be associated with late stage crystallizing phases is described. It is concluded that some of the gold in hydrothermal and volcanogenic deposits may have come from a primary magmatic source rather than having been leached from solid country rock. Gold is probably transported as chloride complexes at temperatures greater than about 300°C. At lower temperatures it is probably transported with other metals as sulphide and thio-sulphide complexes. The precipitation of gold from the transporting medium is brought about by changes in the physico-chemical conditions within that medium. Decrease in pressure is probably not a major cause of precipitation in volcanogenic environments. The geology of volcanogenic iron-formations is described and discussed, relative to the development of greenstone belts. Oxide facies iron-formations were formed in shallow oxidizing environments. They are associated with volcanogenic and clastic sediments. Sulphide facies iron-formations were precipitated in the deeper parts of geosynclinal structures. They are associated with mafic and ultramafic rocks similar to modern oceanic volcanic assemblages. Carbonate facies iron-formations were deposited in the regions between oxide facies and sulphide facies. Other banded iron-formations are found associated with base metal massive sulphide deposits related to arctype volcanic centres. These deposits are found in the regions where carbonate facies iron-formations were formed. Exploration for and exploitation of gold deposits in Archaean iron-formations are discussed. Geochemical exploration programmes are aided by the association of gold with trace amounts of base metals. Geophysical exploration methods that can be employed include magnetometer, I.P. and E.M. surveys. The metallurgical treatment of the ores should include "roasting" because a large proportion of the gold occurs as submicroscopic grains within sulphide mineral crystals.

The general characteristics of gold deposits are reviewed, and a classification of gold deposits based on mineability is proposed. Evaluation, mlnlng and beneficiation methods are briefly discussed. It is concluded that the most viable targets for small-scale companies comprise deposits that require the least pre-production time and expense. Great potential exists for the small-scale reclamation of gold from tailings dumps and abandoned mines in Southern Africa. There is also potential for developing new smallscale gold mines in the Archaean greenstone terranes of the Zimbabwean and Kaapvaal cratons.

The first Witwatersrand gold deposits in the Orange Free State were discovered under younger cover rocks in the 1930's with the aid of drilling and geophysics. The Welkom gold deposits are found in the sedimentary rock sequences of the Central Rand Group, which represent unconformity bounded genetic packages. The structural configuration of the goldfield is one of a north to south trending synform that is split near it's axis by the De Bron and Homestead faults. The "B" Reef is a highly variable, erratically mineralised reef that lies on an unconformity at the base of the Spes Bona Formation. The "A" Reef Zone consists of several placers 1 including the "Reworked BPM" 1 the Witpan, the Uitsig, the Hanging Wall Grits and the Upper "A" Reef. The Beatrix Reef lies at the base of the Eldorado Formation on an unconformity surface overlying the Virginia Formation in the southern part of the Welkom Goldfield. The origin of gold in the Witwatersrand basin can be classified into the modified placer theory, the syngenetic theory and the epigenetic theory. From the distribution of basin edge unconformities it can be deduced that the Welkom fan depository was tectonically active on the western, southern and eastern margins during sedimentation. Palaeocurrent studies indicate that sediment was transported predominantly from the south and west. It is thought that the "B", "A" and Beatrix Reefs were all deposited in a braided stream environment. A multidisciplinary approach to ore evaluation of Witwatersrand deposits is considered to be the best method, where sedimentology, geostatistics and structural geology are used.

M.Sc. (Geology) / The Main Reef Complex (MRC) section is developed in the Zwartkoppie and Sheba Formations of the Onverwacht and Fig Tree Group respectively. The section is represented by three shear zones, associated with a prominent anticlinal structure, locally known as the Birthday No.2 anticline. This tight isoclinal structure is marked by a chert unit, with a core of green quartz-carbonate schist, and is overlain and surrounded by greywackes and shales of the Sheba Formation. At depth the main mineralized fracture occurs to the south of, and parallel to the Birthday No.2 chert bar. Above the crest of the anticlinal structure gold mineralization is associated with three shear zones (which transgress the bedding of the greywackes and shales) known as the No .. I, No. 2 and No. 3 Fractures. Pyrite and arsenopyrite are the main ore minerals, with minor amounts of chalcopyrite, sphalerite, tetrahedrite and pyrrhotite. Pyrite mineralization is ubiquitously developed along the shear zones, while arsenopyrite mineralization is restricted to certain areas. Assay data of the greywackes and shales show that there is a correlation between gold contents and the abundance of arsenopyrite. Gold has been observed in association with all the sulphide minerals present, and as inclusions within pyrite and arsenopyrite. Electron microprobe analyses have revealed significant levels of gold in arsenopyrite, probably as submicroscopic inclusions.

M.Comm. / The South African gold mining industry has in the last decade increasingly come under pressure. The radical drop in the dollar price of gold, the lowest it has been in 16 years, has depressed revenues to the point where drastic action is needed. Furthermore, costs have been escalating. Where the South African Industry was the international leader in low cost production ten years ago, it has now become the most expensive. The following statement by the Chamber of Mines President, Bobby Godsell (1998: Godsell) , underlines the problem: "The gold mining industry world-wide is in a state of crisis, with the price of its product at a 16-year low. Few industries would not be in crisis if they were receiving 1982 prices for their product. In South Africa, two other features contribute to an even more acute crisis. Over the last decade South Africa has moved from being the lowest cost major gold producer to being the highest. Secondly, many South African gold companies are facing physical depletion of their ore reserves. Many companies have now been in operation for more than half a century. Eventually every mine must come to the end of its mineable reserves. Members of the Chamber are deeply committed to meeting the challenges of low prices, high costs and one depletion constructively and effectively. To this end the Chamber proposed a productivity-linked wage agreement last year. Since that agreement we have seen a further $30-drop in the gold price, with a third of Chamber member gold mines making losses, aggregating about R12-million a week. The Chamber shares the National Union of Mineworkers' concerns about job losses. Retrenchments are the consequences of the industry's problems - not their causes. Without addressing the causes, a moratorium on retrenchments will, in our view,achieve nothing, and possibly create expectations which would not be fulfilled. There is only one way to reduce job losses and this is to find ways to return companies to profitability and to make them cost-competitive with producers of gold elsewhere in the world. Much as it understands the National Union of Mineworkers' anger, the industry will not find a way forward through marches, protests or strikes. The combined wisdom, and then the combined effort of management, labour and government will be required to find a way forward for the South African gold industry."

D.Ing. (Civil Engineering) / This thesis describes an Investigation Into the nature of the fracture and deformation mechanism which occur at the edges of tabular gold mining excavation. Published Information on these phenomena Is reviewed, and the necessary underground Investigation required to consolidate the previous work Is described. It Is concluded that the rock near the reef plane at the edges of these mining excavations Is subject to stresses sufficiently high to cause It to fracture through the formation of regular patterns of shear planes. These fractures can form In the solid rock some distance ahead of the mining excavation. Nearer the mining face, extension fractures form which result In slabbing or splitting of the exposed rock. An Idealization of the observed rock behavior Is proposed, which Is then incorporated with conventional boundary element techniques Into a numerical model (SEAMS) which Is capable of analyzing two Dimensional tabular mining excavations where the rock near the reef plane at the edge of the mining excavation fractures, deforms and sheds load. A Sensitivity analysis of the numerical model Is described which Identifies those mining parameters capable of being used to advantage In controlling the size of the fracture zone.

D.Phil. (Geology) / The structural history and mechanisms of bedding-parallel faulting associated with the Ventersdorp Contact Reef (VCR) on the Kloof Gold Mine are discussed. Pre-VCR deformation is determined by folding of the Booysens Shale Formation and the Turffontein Subgroup. Extension of Ventersdorp age (± 2700 Ma) probably took place by the simultaneous operation of normal, strike-slip and oblique slip faults (mixed-mode extension). Because the strikeslip and oblique-slip faults were extensional, they could be utilised as conduits for dykes, forming "Fault and Dyke Zones". Northwestward directed thrusting, which postdates the normal faulting, resulted in positive inversion. The thrust faults have a ramp-flat symmetry with ramps forming in the VCR horizon and the overlying Alberton Formation and flats forming in the underlying Booysens Shale Formation and along the contact between the VCR and the Alberton Formation. The thrust faults follow complex deformation paths, indicated by out-of-sequence thrusting, simultaneous folding and thrusting, underthrusting and compressed boudins. Hanging-wall ripouts, which can be related to this thrust event, are introduced as a shear sense indicator. No northwestward verging thrust faults of post-Transvaal age (post 2430 Ma) could be identified, indicating that this compressional event occurred prior to the deposition of the Black Reef Quartzite Formation. The minimum amount of shortening due to northwestward directed thrusting was estimated as 37 % with the help of restored sections. However, due to the out-of-sequence propagation of thrust faults, a control of the strain estimation was possible and true shortening probably exceeded the calculated amount of shortening considerably. The restoration of sections with out-of sequence thrusts is discussed in detail. Sheath fold-like structures in pseudotachylyte can be related to northwestward directed thrusting and are introduced as a new shear sense indicator.

M.Com. (Business Management) / South-Africa's market share in gold produced dropped from 80 percent in 1980 to about 34 percent currently. This is due to entrance of cheaper producers of gold on the world market. The USA is our main competitor with a market share of about 17 percent. The difference is that South-Africa's remaining reserves is deep below surface and the USA are using open pit techniques to mine cheaply. In order for South-Africa to stay competitive and win back the lost market share it will be necessary to utilise the current available ore resources to it's full potential. This will also create new jobs in a South-Africa that needs it desperately. The calculation of the pay limit is investigated and found to be adequate. The different types of pay limits and their usage was explained. It was found that the current method, of using the pay limit directly as a cutoff limit, was incorrect. The use of a proposed pay limit was suggested. The definition of the proposed pay limit is slightly different than the current pay limit changed in order to clarify the correct use of the pay limit. The inadequacies of the pay limit was recognised and explained. A new term in gold mining was formulated namely the optimal limit. The purpose of this cutoff limit is to determine the cutoff value at which the resultant grade will be such that the mine's profit will be maximised over the long term. The combined usage of the proposed pay limit and the optimal limit in order to manage the ore resource, was described. This method of ore resource management is easily understandable, easy to use and addresses the inadequacies of the current pay limit successfully.

While as South Africans, we support the dream of an African Renaissance our developing country and economy has experienced a critical shortage of skills, which is clearly reflected in our matured gold mining industry. Against this background, I undertook a modernist qualitative study to (i) capture, describe, understand skills development on a marginal South African gold mine, and (ii) create a development framework for human development. Using symbolic interactionism as broad theoretical framework I designed a single case study, gathered material first hand through 22 unstructured in-depth interviews and other data sources, analysed the material by applying a blended strategy of grounded theory and analytical induction created with a black male skills development facilitator storyteller his life history. Exploring the fifteen sets of legislated transformational requirements, over forty practical opportunities emerged, including an indigenous mindset and cultural theme, UBUNTU. In addition to the range of recommendations, an UBUNTU driven skills development framework is suggested as catalyst for optimizing human resources development on our marginal gold mines. This broad framework could facilitate a learning culture where people could experience service delivery of legislation, implementation of existing policy, and effective skills development. The two-year study was generally written as a realist tale, which as I left the research scene represented a co-constructed story bordering an autoethnographical tale. / Prof. Willem Schurink

Department of Mining and Environmental Geology / MESMEG