Dissertations / Theses on the topic 'Mineralogy – South Africa'

The Townlands iron-rich ultramafic pegmatite is a relatively large pipelike body situated in the western corner of Rustenburg Section, Rustenburg Platinum Mines. It is characterised by a strong negative magnetic signature and transgresses the noritic layered sequence of the upper critical zone of the Bushveld Complex. The layered rocks are downwarped in the vicinity of the pipe and are in sharp contact with the pegmatitic material. The pegmatite varies in composition between dunite and wehrlite, with the marginal zones being more wehrlitic in composition. Olivine (Fo₃₀ - Fo₅₂) and clinopyroxene (Wo₄₅En₃₀Fs₂₅ - Wo₄₅En₃₇Fs₁₈) are the dominant constituents and accessory phases include ilmenite, Ti -magnetite, apatite, amphiboles, chlorite-group minerals, biotite, ilvaite and a host of unusual ore minerals. The Fe-Ti oxides exhibit exsolution textures typically found in slowly cooled igneous rocks and temperatures of formati on are consi dered to be in excess of 800°C. The UG2 chromitite leader layers intersected by borehole TLP.l are enriched in Fe and Ti and exhibit compositions intermediate between chromite and Ti-magnetite. The ore mineral assemblage includes a primary sulphide assemblage consisting of troilite, chalcopyrite, cubanite and pentlandite, and an array of unusual phases formed by late-stage secondary processes. The unusual sulphides mooihoekite and haycockite, that occur in certain parts of the pegmatite, are considered to have formed by partial replacement of the primary assemblage and a possible paragenetic sequence is discussed. Mineral compositions and whole rock geochemical data are consistent with an origin for the pegmatite by crystallization from a fractionated melt. It is suggested that intercumulus fluids, trapped during the crystallization of the noritic layered sequence, accumulated in an area of structural weakness, in response to an increasing overburden pressure and/or tectonic activity. Evidence is also presented that indicates that the Townlands pegmatite may consist of at least two separate, but adjoining pegmatite bodies.
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Banded iron-formations (BIFs) are chemically precipitated sedimentary rocks in which Fe-rich bands or laminae alternate with Fe-poor ones. They formed within a specific time-span of the geological record. Their occurrence is restricted between 2.3 and 1.9 Ga, and characterises virtually all the major Precambrian-aged sedimentary basins of the world. The Precambrian Transvaal Basin in Griqualand West, South Africa, is noted for its well-developed BIF units. The Kuruman and Griquatown BIFs comprising the Asbesheuwels Subgroup (up to 1000m thick) are the best known and thickest of these. As far as metallogenesis is concerned, the Kuruman BIF is of major importance, for it carries the world's largest crocidolite (blue asbestos) deposits. The uppermost, youngest member of iron-formation deposition in the Griqualand West Sequence is represented by the Voëlwater BIF. The direct association between the latter and the giant Mn-deposits of the Kalahari Field, renders the Voëlwater association unusual, if not unique, in the geological record. The Voëlwater BIF represents a typical example of the so-called "Superior-type", and in the area of study it has undergone late-diagennetic to low-grade metamorphic processes. This is evident from the mineralogical composition and textural signature of the various BIF lithologies. Specifically, the minerals that make up the Voëlwater BIF are mainly chert(quartz), Fe-oxides (magnetite and hematite), Fe-silicates (greenalite, stilpnomelane, minnesotaite, riebeckite, Fe-mica), Fe-carbonates (members of the dolomite-ankerite series and siderite), calcite and pyrite. Soft-sediment deformation structures and shear-stress indicators are abundant in carbonate-rich and granular, silicate-rich BIF lithologies respectively. The bulk chemical composition of the study rocks is relatively simple and is characterised by the abundance of essentially three elements, namely Si, Fe, and Ca, which make up more than 90% of the total chemical composition of the Voëlwater BIFs. The detrital component of the study rocks is negligible. Mn-enrichments characterise all the transitional lithologies towards the interbedded Mn-orebodies, as well as the well-developed, hematitic BIF-unit between the Ongeluk lavas and the lower Mn-horizon. In terms of trace element composition, no significant enrichments or depletions, were encountered, except for some unusually high values of Sr and Ba and Co in carbonate-rich and Mn-rich lithologies respectively. Geochemical comparisons on the basis of major, trace and light rare-earth element composition verified the similarity between the Voëlwater BIF and other major Superior-type BIFs of the world (e.g. Kuruman, Griquatown, Sokoman, Biwabik, Gunflint, Mara-Mamba, Brockman, etc.). The processes that led to the formation of the Voëlwater BIFs may have been very similar to the ones described in various genetic models proposed in recent years. They would have involved a combination of: i. hydrothermal processes related to mid-ocean ridge (MOR) or hot-spot activity that acted as major iron suppliers; ii. storm-mixing in stratified oceans (bottom, anoxic, Fe⁺² reservoir-thermo- pycnocline zone-upper, mixed, SiO₂-saturated layer), largely dictated by seasonal changes and contemporaneous volcanism; iii. periodic, convection-driven upwelling mechanisms acting as major Fe-precipitators; and, iv. organic carbon productivity that was responsible for the anoxic diagenesis of the initial sediment. However, the origin of Fe and Mn for the genesis of the Voëlwater sediments was difficult to explain with typical convection-cell models in active mid-ocean ridges, in contrast to previous hypotheses. Instead, large-scale endogenous processes in the form of magma convection, underplating, differentiation and associated degassing, may have played a critical role in the supply of metals for the formation of large amounts of BIFs in the Precambrian. The present study of the Voëlwater BIF also bears strong implications regarding the metallogenesis of Mn in the Precambrian. The common association of Mn with carbonate-bearing sediments, the transitional character of the Voëlwater BIF towards carbonate lithologies (Mooidraai dolomites) and the critical timing of the deposition of the former in terms of the Precambrian atmospheric-lithospheric- hydrospheric evolution, may be important indicators for the exploration of large Mn-deposits in Precambrian sedimentary basins of the world.

The variations in the composition, specifically the Cr20 S content and the Cr:Fe ratio, and the morphology of the Lower Group (LG) and Middle Group (MG) chromitite seams of the Critical Zone (CZ) across the western Bushveld Complex, including the Ruighoek and Brits sections, is investigated by means of whole-rock chemical data, both major and trace elements analysis, XRD and electron microprobe data. As a result ofthe paucity of exposed or developed LG1 - LG5 chromitite seams in the western Bushveld Complex, this study is confined to the investigation of the compositional variations of the LG6 to MG4 chromitite seams. In only one section, the Ruighoek section, was the entire succession of chromitite seams, from the LG1 - MG4, exposed. The silicate host rocks from the LG6 pyroxenite footwall to the collar of the CC2 drillcore (lower uCZ) in the Rustenburg section were sampled. This study reviews the compositional trends of the silicate host rocks, as the compositional variations of the chromitite seams reflect the chemical evolution of the host cumulate environment and, to a lesser degree, the composition onhe interstitial mineral phases in the chromitite seams. The compositional variations of the LG and MG chromitite seams are attributed to the compositional contrast between the replenishing magma and the resident magma. The chemical trends of the LG and MG chromitite layers and the host cumUlate rOCKS do not support the existence of two compositionalfy dissimilar magmas in the CZ, rather the cyclic layering of the CZ and the chemical variations of the chromitite seams are attributed to the mixing of primitive magma with the resident magma, both of which have essentially similar compositions. The compositional variations of the LG and MG chromitite seams along strike away from the supposed feeder site (Union section) to the distal facies (Brits section) are attributed to the advanced compositional contrast between the resident magma and the replenishing primitive magma pulses. The CZ is characterized by reversals in fractionation trends and this is attributed to the compositional evolution of the parental magma and not to the replenishment of the resident magma by influxes of grossly dissimilar magma compositions. The Cr20 S content and the Cr:Fe ratio of the MG chromitite layers increase from the Ruighoek (near proximal) section to the Brits section (distal facies). This is attributed to the advanced compositional contrasts between the resident magma and the replenishing primitive magma. In contrast, the Cr20 3 content and Cr:Fe ratios ofthe LG6 and LG8a chromitite seams decreases eastwards from the Ruighoek section. The average Cr:Fe ratio for the western Bushveld Complex is between 1.5 and\2.0, nonetheless, a progressively lower Cr:Fe ratio is noted from the LG1 chromitite up through to the MG4 chromitite seam in the Ruighoek section. tn the LG2 - LG4 chromitite interval a deviation to higher.lratios is encountered. A progressive substitution of Cr by AT and Fe in the Cr-spinel crystal lattice characterizes the chromitite succession from the LG1 seam up through the chromitite succession to MG4. The petrogeneSiS of the chromitite seams of the CZ is attributed to magma mixing and fractional crystallization of a single magma type.

Scheelite, wolfram Ite and cassIterIte mIneralizat ion is hosted wIthin numerous quartz-tourmaline-feldspar-fluorite veins at Van Rooi's Vley, N.W. Cape Province . MineralizatIon and hydrothermal alteration within, and around, these veins is hIghly complex and reflects the intricate interaction of hydrotherma l activity upon a structurally deformed sequence of ProterozoIc med ium to high-grade gneisses. Four distinct stages of alteration and mineralization occurred, including a l ate 'epithermal stage'. Although the location of mineralization was strongly controlled by st ructure, the concentration of mineralizati on was controlled by physicochemical variables, of which host-rock geochemistry was particularly important . Further W/Sn mineralization occurs on a local scale, some of which is spatia lly related to minor leucogranite dykes. Leucogranite bodies are not uncommon within the region and some are enriched in Wand Sn. By comparing FIB ra tio s,W/Sn ratios, the alteration mineralogy, the ore mineralogy and the Fe-content of tourmaline, the deposits within the Van Rooi's Vley area can be placed into a 'proximal' to 'distal' classification, with respect to a common source of mineralizing hydrothermal fluids. The Van Rooi's Vley deposit, whilst affiliated to greisen-style deposits, represents a ' distal' quartz-vein lode deposit.
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This study of the lower part of the Rustenburg Layered Suite in the Western Bushveld Complex is based mainly on drill core samples from three localities, which are approximately 130 km apart. The NG-sequence, situated in the northwestern sector of the complex (Union Section, R.P.M.) extends from the floor of the complex to the base of the upper Critical Zone. The sequence is ca. 1800 m thick and it comprises mainly ultramafic cumulates, namely pyroxenites, olivine pyroxenites, harzburgites and dunites. Norites and anorthos ites are present only in minor proportion. Within the upper half of the NG-sequence ten prominent chromitite layers are correlated with the LGI MG4-interval. Correlation is also established between published sequences and the two other sequences studied, located 8 km and 55 km, respectively, east of Rustenburg. Whole-rock chemical data (major and trace elements), microprobe and Sr isotope data are presented. Petrographic studies provide modal analyses and measurements of grain size. All petrographic, mineralogical and other geochemical data point to an origin of the cumulates of the NG-sequence by crystallization from liquids of the U-type lineage and derivatives thereof. No evidence is found for the involvement of parental liquids with a distinctly different composition or crystallization order (A-liquids). However, subtle compositional variations of the parental liquids are evident in slight changes of the Cr content in orthopyroxene or in variations of Sr isotope ratio. The NG-sequence is characterized by intervals with reversed fractionation trends caused by repeated influxes of pristine magma (during periods of high magmatic activity) resulting in a high degree of rejuvenation. These intervals are overlain by others with a normal fractionation trend, interpreted as cumulates formed in periods with low or no magmatic activity, in which fractional crystallization controlled bulk composition of the evolving liquid. The Lower Zone in the NG-sequence is dominated by a progressive shift towards more primitive compositions, while in the Critical Zone fractionation was the major operating process in the magma chamber. However, during deposition of the pyroxenitic lower Critical Zone several replenishment events occurred, during which fresh Cr-rich magma was emplaced. Massive chromitite layers were deposited after mixing between the newly emplaced magma and the resident residual liquid shifted bulk compositions into the primary field of chrome-spinel. Cumulus plagioclase crystallized after bulk composition of the residual liquid was driven to the orthopyroxene plagioclase cotectic by continued fractional crystallization; this occurred once in the Lower Zone, yielding a single, thin norite layer, and again in the upper Critical Zone of the NG-sequence. A facies model is proposed based on the stratigraphic and compositional variations along strike in the Western Bushveld Complex. This model explains the variations by means of the position of the sequence with regard to a feeder system. The olivine- and orthopyroxene-rich, but plagioclase-poor NG-sequence represents the proximal facies, while the SF-sequence (poor in ferromagnesian phases, but plagioclase-rich) is developed as a distal facies, close to the Brits graben.

Union Section of Rustenburg Patinum Mines is situated in the northwestern part of the Bushveld Complex, some twenty kilometres north of the Pilanesberg Alkaline Complex. The mining lease area covers a roughly triangular segment of Lower, Critical and Main Zone rocks, transgressed to the north and south by magnetite-bearing ferrogabbro of the Upper Zone. The Main Zone at Union Section is the focus of this study. The prime source of sample material for the study is the deep exploration borehole SK2, but additional, supplementary samples were collected on surface and underground, as well as from a second surface exploration borehole, SK4. In line with the recommendations of SACS (1980), the top of the Critical Zone, and therefore the base of the Main Zone, is taken to be the top of the Bastard Cyclic Unit. Sharpe (1985) suggested that the succession from the base of the Main is an isotopically separate entity Zone up to the Pyroxenite Marker from the rest of the Bushveld layered succession. This is not strictly true, as there is evidence that more than one parental magma was involved in the formation of this interval. It is, however, true that there are fundamental differences, particularly in isotopic makeup, between the Main Zone rocks below the pyroxenite Marker and those above (the latter having been assigned by Molyneux (1970) to subzone C of the Main Zone). Kruger et al. (1986, in press) suggested that the Pyroxenite Marker marks the base of the Upper Zone, and this convention is adhered to here. The implication of this is that the rocks which formerly constituted subzone C of the Main Zone are now considered part of the Upper Zone. The Main Zone rocks below the pyroxenite Marker were originally subdivided by Molyneux (1970) into two subzones, A and B. The results of the present study indicate that this subdivision is not justified. Instead, eight units have been distinguished in the Main Zone on geochemical, petrological and mineralogical bases. Each of these units is characterized by a coherent set, or progression, of chemical and petrological characteristics. The specific assignment of genetic connotations to these units has been deliberately avoided , at least until further studies of the Main Zone prove this to be justified. The demarcation of the eight units is illustrated in the composite diagram (Fig. 34) in the back pocket of this work, and the reasons for the subdivisions are listed in Table 6 (at the end of chapter 7 of this thesis). Until the late 1970's, it was thought that most layered cumulates formed by crystal settling (Wager and Brown, 1968). More recently, there has been a fundamental conceptual change, and many workers now believe that most cumulate rocks formed by in situ crystallization at the floor and walls of the magma chamber (McBirney and Noyes, 1979, Irvine, 1980a; Campbell, 1987). There is, however, some evidence for the physical separation of phases undergoing cotectic crystallization, particularly in the Upper Critical Zone and lower part of the Main Zone (Eales et al., 1986). This process, which has been alluded to in the past by various authors (Ferguson and Botha, 1963; Vermaak, 1976) involves the flotation of early-formed plagioclase crystals due to their positive bouyancy in tholeiitic liquids. The result is an apparent decoupling of the chemistry of pyroxene and plagioclase, as in unit IV of the Main Zone, where plagioclase becomes more anorthitic upwards, whilst pyroxene becomes more iron-rich. There is some substantial evidence, particularly in reversals in the strontium isotope initial ratio and the orthopyroxene Mg/(Mg+Fe) ratio , for multiple intrusion in the Main Zone. Although the largest and most important magma influx in the Main Zone was a high-R₀ aluminous tholeiite, as suggested by Sharpe (1985), the intrusive history of the Main Zone is believed to be far more complex than Sharpe (op. cit.) suggested. Significantly, there is strong evidence for small influxes of Upper Zone-type (Fe-rich tholeiite) magma in the upper reaches of the Main Zone. These are believed to be precursors to the major influx of Upper Zone-type magma at the pyroxenite Marker (Kruger et al, 1986, in press). The fate of intercumulus liquids in cumulate rocks has recently recieved substantial attention (Sparks et al., 1985; Morse, 1986; Barnes, 1986: Campbell, 1987). It is believed that the migration, or at least redistribution, of intercumulus liquids has played a vital role in modifying fractionation trends in the Main Zone. More importantly, the accumulation of late-stage intercumulus liquids is believed to be responsible for the formation of the Fe-rich ultramafic pegmatite bodies that interrupt the layered cumulates in borehole SK2
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The main Karoo Basin of South Africa contains a relatively continuous sequence of continental deposits that accumulated over a 100 million year period from Permo-Carboniferous (280 Ma) to early Jurassic (180 Ma). In the southwestern region of the basin the Karoo succession is approximately 4 000 m thick, the upper half of which consists of vertebrate fossil-bearing fluvial rocks of the Beaufort Group. This study deals with Lower Beaufort (Adelaide Subgroup) strata belonging to the Teekloof Formation which are exposed in the cast-west trending erosional escarpment between the towns of Beaufort West and Fraserburg in the central Cape Province. The 450-mctre succession consists mainly of vertically accreted floodplain mudrocks with interbedded continuous sheets of fine-grained sandstone that bear evidence of having accumulated by lateral accretion on the inner banks of meandering channels. The mudrocks contain numerous fossilized skeletons of therapsid "mammal-like" reptiles as well as more primitive cotylosaurs and a few amphibians. Rarely, impressions of Glossopteris leaves and equisetalcan stems are found although root moulds are relatively abundant. Several types of calcareous nodules and sheets occur in the mudrocks and arc interpreted as evidence of calcic palaeosols that formed under semi-arid climatic conditions. This is an interdisciplinary study that integrates a conventional sedimentary facies analysis with investigations of the taphonomy of in situ therapsid fossils and the nature and distribution of palaeosols. Such an approach has not previously been applied to any of the Karoo strata. The results contain descriptive and quantitative information on sedimentary processes, palaeohydrology, absolute time represented in the stratigraphic record and the topography, soils and habitats of the ancient landscape. These are summarized into a palaeoenvironmental synthesis of the Teckloof Formation.

Thesis (MScAgric)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: In the humid Graskop region of Mpumalanga Province, South Africa, there is an anomalous body of highly weathered black, manganiferous oxisols derived from dolomite. With Mn contents as high as 17%, potential large-scale Mn release is an environmental concern under current, acid generating, forestry practices. This study aims at establishing the factors which may affect the stability of the manganiferous oxisols of Graskop and in the process, investigating some of the morphological, mineralogical and chemical properties of these unique soils. Typically, the soils show a reddish, nodule-rich horizon, containing 3-4% Mn, grading through a red and black mottled zone into a black (5YR 2.5/1) apedal subsoil with >7% Mn. The Mn gradient down the profile as well as the abundant nodule content of the upper subsoil horizons implies that Mn mobilization and redistribution are active pedogenic processes. The exceptional Mn content of these soils is complemented with Fe and Al concentrations of up to 10 and 8%, respectively, and anomalously high trace element levels in particular Ni and Zn (as high as 541 and 237 mg kg-1, respectively) which are at the upper limit of cited world natural maxima for soils. The Mn mineral lithiophorite [(Al,Li)MnO2(OH)2], dominates the mineralogy of the soils with accessory amounts of birnessite, gibbsite, goethite, hematite, maghemite, kaolinite, aluminous chlorite and mica - a mineral suite reflecting that of well weathered soils. With the pH of the soil being at or close to the point of zero charge (4.5-5.5) the soils show isoelectric equilibrium. The very low buffer capacity results in metal dissolution commencing with the first increment of titrated acidity. Manganese dissolution is relatively minor considering the large potential for release and is highly overshadowed by Al release. The apparent resilience of the Mn phase to added acidity may relate to the overwhelming poise of the soils which maintains robust, oxic conditions despite the usual instability of Mn oxides at low pH. Manganese release and soil redox properties are substantially affected by drying especially in the organic rich topsoils. Using various redox analyses, evidence is shown for involvement of Mn(III)-organic complexes in the drying reactions. Using this and information gained in a real time, attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopic study, a mechanism is suggested which may account for the observed Mn release and the loss of Cr oxidising capacity commonly observed in dried soils. The information provided by the ATR-FTIR study showed the decrease in surface pH of a clay film, from 5 to below 2, as well as the shift in coordination nature of sorbed oxalate from a more outer-sphere association to a more inner-sphere association concomitant with the removal of free water from the clay surface. This spectroscopic evidence for these chemical changes which accompany surface drying not only provides further insight into the reactions involving Mn oxides in soils but also highlights the suitability of ATR-FTIR for real time, in situ investigation into the chemistry of the drying water interface. From these results it is concluded that Mn release from the manganiferous oxisols, under acid generation of the kind known to occur in pine plantations, is less that anticipated. On the other hand, desiccation of the topsoil results in substantial Mn release with a suggested mechanism which involves a Mn(III) intermediate.
AFRIKAANSE OPSOMMING: ‘n Onreelmatige grondliggaam van hoogs verweerde, swart, mangaanhoudende oxisols wat uit dolomiet ontwikkel het, word in die humiede Graskop streek van die Mpumalanga Provinsie van Suid-Afrika aangetref. Die hoë Mn-inhoud (tot 17%) van hierdie oxisols is van groot omgewings-belang weens die potensiële grootskaalse Mn-vrystelling onder huidige, suur-genererende bosbou praktyke. Hierdie studie beoog om die faktore wat die stabiliteit van die mangaanhoudende oxisols van Graskop affekteer, vas te stel. Tesame hiermee word die morfologiese, mineralogiese en chemiese eienskappe van hierdie unieke gronde ondersoek. Kenmerkend van hierdie gronde is ‘n rooi, nodule-ryke horison met 3-4% Mn aan die oppervlakte. Bogenoemde horison verander met toename in diepte in ‘n rooi en swart gevlekte sone wat weer in ‘n swart (5YR 2.5/1) apedale ondergrond met >7% Mn oorgaan. Die Mn gradiënt in die profiel sowel as die hoë nodule-inhoud van die boonste grondhorison dui daarop dat Mn-mobilisasie en -herverspreiding huidige aktiewe pedogenetiese prosesse in die profiele is. Fe en Al, met konsentrasies van 10% en 8% onderskeidelik, word saam met die onreelmatig hoë Mn inhoud aangetref. Baie hoë vlakke van Ni en Zn (so hoog as 541 en 237 mg.kg-1 onderskeidelik) wat hoër is as aangehaalde wêreld natuurlike maksimum waardes, word ook aangetref. Die mineralogie van die gronde word deur die Mn mineraal litioforiet [(Al,Li)MnO2(OH)2] gedomineer. Bykomstige hoeveelhede van birnessiet, gibbsiet, goethiet, hematiet, maghemiet, kaoliniet, aluminiumryke chloried en mika word ook aangetref. Hierdie minerale samestelling is kenmerkend van hoogs verweerde gronde. Met die pH van die grond in die omgewing van die punt van geen lading (4.5 – 5.5), word ‘n iso-elektriese ekwilibrium by die gronde aangetref. Die baie lae bufferkapasiteit het metaal-oplossing aangehelp wat met die eerste inkrement van titreerbare suurheid ‘n aanvang geneem het. Mangaan-oplossing is baie klein indien die groot potensiaal vir vrystelling asook die groot mate van Al-vrystelling in ag geneem word. Die skynbare teenwerking van die Mn fase tot toegevoegde suurheid, mag toegeskryf word aan diesterk ewewig van die gronde om sterk, oksiese kondisies, ten spyte van die normale onstabiliteit van Mn oksiedes by lae pH, te onderhou. Mangaan vrystelling en grond redoks eienskappe word beduidend deur uitdroging beïnvloed en veral in die organies-ryke bogronde. Deur van verskeie redoks analises gebruik te maak is daar bewyse van die betrokkenheid van Mn(III)-organiese komplekse in die uitdroging-reaksies gevind. Dit. en data ingesamel in ‘n “real time, attenuated total reflectance Fourier transform infrared (ATR-FTIR)” spektroskopiese studie, is gebruik om ‘n meganisme voor te stel wat die waargenome Mn vrystelling en die verlies aan Cr oksidasie kapasiteit (algemeen waargeneem in droë gronde) te kan verklaar. Die data verkry met die ATR-FTIR studie het ‘n afname in oppervlak pH van 5 na 2 van ‘n klei film asook die verskuiwing in koördinasie toestand van die gesorbeerde oksalaat van ‘n meer buite-sfeer assosiasie tot ‘n meer binne-sfeer assosiasie, gepaardgaande met die verwydering van vry water van die klei oppervlaktes, uitgewys. Die spektroskopiese bewyse vir die chemiese veranderinge wat die oppervlak uitdroging vergesel, gee nie net meer insig in die reaksies rakende Mn oksiedes in gronde nie maar onderstreep ook die toepasbaarheid van die ATR-FTIR vir intydse (“real time”), in situ ondersoeke na die chemie van die uitdrogende water kontakvlak. Vanuit hierdie resultate kan afgelei word dat Mn vrystelling vanuit mangaanhoudende oxisols onder suur genererende denne plantasies laer is as wat verwag is. Aan die ander kant sal uitdroging van die bogrond tot aansienlike Mn vrystelling, met ‘n verwagte meganisme wat Mn (III) as intermediêre toestand insluit, lei.

The Kalagadi Manganese mine in the Kuruman area of the Northern Cape Province of South Africa contains reserves of Mn ore in excess of 100Mt. Mineralization in the mine lease area is restricted within the Hotazel Formation of the Voȅlwater Subgroup, belonging to the Postmasburg Group, the upper subdivision of the Transvaal Supergroup. Surface topography is characterized by flat lying, undulation with minimal faulting and the ore are slightly metarmophosed. This study investigates the general geology of the mine, lithostratigraphic subdivision and correlation of the economic Lower Manganese Orebody (LMO) of the Kalagadi Manganese Mine in order to guide mining plan and operations once the mine is fully commissioned. At the commencement of this study, Kalagadi Manganese mine was a project under exploration with no specific geology of the mine lease area and no lithostratigraphic subdivision. The study also aimed determining the extent of lithostratigraphic correlation between the LMO economic orebodies of the Kalagadi Manganese mine with that of underground Gloria and open-pit Mamatwan mines. Four methods including petrographic microscope, Scanning electron Microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses were applied mainly for the mineral identification, chemical composition and ore characterization of the Lower Manganese Orebody (LMO) at Kalagadi Manganese mine. The results of this study indicates the following: (1) Eleven textural distinct zones with economic zones restricted to the middle while the lower grade zones are confined to the top and bottom of the LMO; (2) The economic zones, comprising of Y, M, C and N subzones attain an average thickness of 10 m and are graded at an average of 40% Mn while the Mn/Fe ratio varies from 6 to 9; (3) The most economic zones are M and N subzones which are mostly characterized by oxidized ovoids and laminae, a characteristic applicable even to other zones of economic interest; (4) Braunite is the main mineral of the manganese ore and is often integrown with kutnahorite and other minerals (hematite, hausmannite, Mg-calcite, calcite, jacobsite, serpentine and garnet) which are present in variable amounts; (5) The Mg-rich calcite (Ca, Mg)CO3 is the second dominant manganese carbonate mineral and it corresponds to elevated MgO concentration and is often associated with marine environment. The occurrence of the Mgcalcite is not common in the manganese ore of this area except for the Mn-calcite, which was not determined by XRD analyses in this study; (6) MnO is the most abundant major oxide in the manganese ore while other major oxides present in decreasing order of abundance are CaO, SiO2, Fe2O3, and MgO. The oxides TiO2, Na2O, K2O, Al2O3, and Cr2O3 are depleted and are mostly  0.01wt% and  0.001wt% respectively while P2O5 concentrations are low ranging from 0.02wt% to 0.3wt%. The trace element concentrations of Ba, Zn and Sr in most borehole samples are slightly elevated ranging from 100ppm to 3.9% (36000pm) while Co, Cu, Ni, Y, As, Zr, V and La rarely exceed 50ppm. The enrichments of Cu, Zn, Ni, Co and V that are commonly associated with volcanogenic hydrothermal input in chemicals may reach up to 70ppm; (7) The mineralogical and geochemical characteristics of the manganese ore in the Kalagadi Manganese mine lease area are similar to that of Low-Grade Mamatwan-Type ore. The cyclicity (Banded Iron Formation ↔ Hematite lutite ↔ braunite lutite) and alternation of manganese and iron formation have been confirmed; and (8) The oxygen δ18O isotope values (18‰ to 22‰) indicate a slight influence of metamorphism of the manganese ore. No positive correlation exists between δ13C vs δ18O values and Mn vs δ13C values. Such observations indicate minimal action of organic carbon during manganese precipitation where the organic matter was oxidized and manganese content reduced. On the other hand, the manganese carbonates (CaO) are positively correlated with carbon isotope, this indicates diagenetic alteration and the involvement of biogenic carbonate during the formation of manganese carbonates. It is concluded that the lithostratigraphic subdivision at Kalagadi Manganese mine is best correlated physically, mineralogically and geochemically with that of Gloria mine operating in the Low Grade Mamatwan - Type ore while correlation with an open-pit Mamatwan mine is also valid.

Thesis (MScAgric)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: This study is an integral part of a multidisciplinary research project concerning the effects of soil and climate on wine quality. The motive, which led to the setting up of this project, was that producers could not determine beforehand whether a specific location would yield wines of high or low quality. If a specific cultivar were to be planted at the wrong location, then it was likely that wine of table quality would result, rather than the export quality wine that was intended. The long term objectives of this multidisciplinary project were the compilation of guidelines by means of which different sites may be classified according to their potential for the production of high quality wines, and the identification of the most important climatic and soil factors responsible for differences in wine quality and character. In this multidisciplinary project, measurements (soil water, leaf water potential, cane mass and yield) were made under dry land conditions in Sauvignon blanc vineyards at six different localities: five in the Stellenbosch district (Simonsberg, Kuils River, Helshoogte, Papegaaiberg and Devon Valley) and one in Durbanville. Each vineyard was owned by a private commercial producer. The vines were approximately 10 years old in all cases, and were trained on a hedge system. Measurements were made in plots, each of which contained 20 vines. Two different soil types were identified at each locality. Vine growth and wine quality differed markedly on these contrasting soils, even though they were located in close physical proximity. The measurements that were made at high and low production plots at each locality during this study were obtained from points which were not more than 60 m metres apart. An automatic weather station was erected halfway between the two, contrasting, experimental plots. Within the overall scope of the multidisciplinary project, the study which forms the subject of this thesis, concentrated on the effects of soil parent material as a soil forming parameter and as a possible predetermining character with regard to vine growth and wine character. From literature it was clear at the outset of this work that the geology of the coastal wine region is very complex and varies over short distances. The geological history indicates different types of rock formation and rock forming process (sedimentary, igneous as well as metamorphic), plate tectonic activity, mountain building, erosion and weathering, over a period of approximately 1 000 million years. The present landscape includes a coastal plane, hills, and eroding mountains. Statistical analyses indicated that the soils from the different localities could mainly be characterised in terms of differences in their sand size fractions. Soils from Durbanville are dominated by fine sand and correlates with the underlying phyllitic shales. Soils from Kuils River contain significantly more coarse sand when compared with the other sites. This appears to be a reflection of the underlying coarse granitic material, and implies that in situ weathering played an important role in soil development. .The data did not, however, prove that the Kuils River soils formed solely from underlying rocks. The gravel and stone fraction for the Kuils River soils were nevertheless correlated with those of the underlying parent material. Soils from Helshoogte and Simonsberg (both of which are underlain by granites), Papegaaiberg and Devon Valley (both underlain by hornfels) were not significantly dominated by any particular sand fraction. Soils from these localities therefore did not only reflect the underlying material as a source of soil parent material. This implied mixing of parent material and/or the incursion of eolian sand at Helshoogte, Simonsberg and Devon Valley. A marine incursion may have affected the soil parent material at Papegaaiberg. In order to obtain more information concerning the origins and possible mixing of parent materials prior to and during soil formation, samples from the different soil horizons in each profile were subjected to a chemical analysis. Particular emphasis was placed on potassium, which is an extremely important nutrient mineral element, from the viewpoints of vine growth and wine quality. Because the soils used in this study were all located in production vineyards, the probability that fertiliser residues would have contaminated the soils was high. The lower soil horizons were considered to be least affected by this contamination and therefore most likely to be indicative of the natural soil chemical composition. However, the lower horizon K content of the soils in this study could not be reliably correlated with any known or predicted characteristic that might link the soil parent material with local rock types. At Durbanville, both soils contained small quantities of K in the lower horizons, reflecting the underlying phyllitic shales, but at Devon Valley and Papegaaiberg, the lower horizons contained more K than expected. The soils at these localities are situated on hornfels, containing low quantities of K. The large quantities of K in the soils may have indicated that these soils are situated close to a granite/Malmesbury contact zone. Soils from Kuils River, Simonsberg and Helshoogte are situated on K-rich porhyritic granites and it was expected that these soils would contain relatively large quantities of K in the lower horizons. This, however, was not the case. It was therefore concluded that dilution with K-poor material had taken place. Such material could have been derived from higher-lying sandstones, or from eolian processes during the Cenozoic. Alternatively, the K content of the soil might have been depleted by long continued leaching. A semi-quantitative analysis of the minerals in the soil clay fractions was also carried out. The objective was to identify the clay minerals that were present in the different soil horizons and to relate the minerals to weathering conditions. Evidence linking the minerals in the clay fractions of the soil samples with the mineralogical composition of the soil parent materials was sought. The clay fraction mineralogy data indicated that all soils in the study area are in an advanced stage of weathering and are dominated by kaolinite, and in certain soils quartz. It was difficult to relate these minerals directly with soil parent material because the primary minerals originating from the soil parent materials have been extensively broken down. The simultaneous presence of quartz and gibbsite in the clay fraction of both soils at Simonsberg, Helshoogte and Durbanville as well as one soil form from bath Kuils River and Simonsberg, indicated non-uniform distribution of clay fraction minerals, indicating that different stages of weathering were present during soil formation. This could have been a result of mixing of parent materials, but may also reflect different periods of weathering of the same material. Both soils at Papegaaiberg, both soils at Devon Valley and other soils at Simonsberg and Kuils River indicated uniform clay fraction mineralogy distribution, mainly because the absence of gibbsite is related to the presence of quartz in the clay fraction. The soil characteristics, as determined in this study, were also compared with vine growth, wine quality and wine character, as obtained in the broader multidisciplinary research project. For most soils in this study, an increase in clay fraction kaolinite was associated with a reduction in vegetative growth, overall wine quality, and fresh vegetative character. An increase in clay fraction quartz was associated with higher overall wine quality. Increased shoot growth also affected fresh vegetative character positively. Better growth occurred on higher altitudes and this resulted, for Sauvignon blanc, in higher wine quality. Wines produced from vines situated on both phyllitic shales and porhyritic granites showed high quality (Durbanville and Helshoogte), but both were related to low clay fraction kaolinite content and high altitude. It was not possible to relate parent material directly with vine growth, wine quality and/or wine character. The lowest quality wines, however, were produced from vines situated on hornfels (Papegaaiberg and Devon Valley), both containing high quantities of clay fraction kaolinite and situated on low altitudes. High levels of K in soils containing high levels of clay fraction kaolinite may have been partly responsible for low wine quality obtained on such soils.
AFRIKAANSE OPSOMMING: Hierdie studie vorm 'n integrale deel van 'n multi-dissiplinêre navorsingsprojek oor die effek van grond en klimaat op wynkwaliteit. Die motivering wat gelei het tot die beplanning van hierdie projek, was dat produsente nie vooraf kon bepaal of 'n spesifieke lokaliteit wyne kan produseer van hoë of lae kwaliteit nie. Indien 'n spesifieke kultivar op die verkeerde lokaliteit geplant word, sou dit waarskynlik tot In gewone tafelwyn lei, instede van 'n wyn van uitvoergehalte. Die langtermyn doelwitte van die multi-dissiplinêre projek was om riglyne te ontwikkel om verskillende lokaliteite te klassifiseer na aanleiding van·hul potensiaal om hoë kwaliteit wyne te produseer, asook om die belangrikste klimaats- en grondfaktore verantwoordelik vir die produksie van hoê kwalitiet wyne te identifiseer. In hierdie multidissiplinêre projek was metings (plant beskikbare water, blaarwater potensiaal, lootmassa en oes) onder droêland toestande bepaal in Sauvignon blanc wingerde by ses verskillende lokaliteite: vyf in die Stellenbosch distrik (Simonsberg, Kuilsrivier, Helshoogte, Papegaaiberg and Devon Valley) en een in Durbanville. Elke wingerd is besit deur 'n kommersiêle privaatprodusent. Die stokke was ongeveer 10 jaar oud in alle gevalle en opgelei op 'n heining sisteem. Metings was in eksperimentele blokke van 20 stokke elk uitgevoer. Twee verskillende grondtipes is by elke lokaliteit identifiseer. Lootgroei en wynkwaliteit het merkbaar verskilop die kontrasterende gronde, selfs waar gronde nabyaanmekaar was. Die metings is Liitgevoer op hoë- en lae produksie eksperimentele blokke waar gronde by spesifieke lokaliteite nie verder as 60 meter was nie. 'n Outomatiese weerstasie was halfpad tussen die twee kontrasterende grondtipes by elk van die ses lokaliteite opgerig. Binne die algemene omvang van die multi-clissiplinêre projek, het die studie wat die onderwerp van hierdie tesis is, gekonsentreer op die effek van moedermateriaal as grondvormende parameter asook as moontlike voorspeller van wingerdgroei en wynkarakter. Dit was duidelik uit die literatuur dat die geologie van die Wynkusstreek baie kompleks is en oor kort afstande varieer. Die geologiese geskiedenis dui daarop dat verskillende tipes gesteentes en verskillende prosesse van gesteente-vorming (sedimentêr, stollings- en metamorfe), plaattektoniese aktiwiteit, orogenese, erosie en verwering, oor 'n periode van ongeveer 1 000 miljoen jaar plaasgevind het. Die huidige landskap sluit kusvlaktes, heuwels en geêrodeerde berge in. Statistiese analises het aangetoon dat die gronde van die verskillende lokaliteite hoofsaaklik in terme van verskille in sandgrootte fraksies onderskei kon word. Gronde van Durbanville is gedomineer deur fyn sand en korreleer met onderliggende fillietiese skalies. Gronde van Kuilsrivier bevat betekenisvol meer growwe sand wanneer dit vergelyk word met die ander lokaliteite. Dit is waarskynlik afkomstig vanaf die onderliggende growwe granitiese materiaal en impliseer dat in situ verwering 'n belangrike rol gespeel het in grondontwikkeling. Die data het egter nie bewys dat die gronde van Kuilsrivier slegs uit die onderliggende graniete gevorm het nie. Die gruisfraksies in die gronde by Kuilsrivier was tog vergelykbaar met die onderliggende materiaal. Gronde vanaf Helshoogte and Simonsberg (beide onderlê deur graniete), Papegaaiberg and Devon Valley (beide onderlê deur hornfels) was nie betekenisvol gedomineer deur 'n spesifieke sandfraksie nie. Gronde vanaf hierdie lokaliteite het dus nie slegs die onderliggende gesteentes verteenwoordig nie. Dit dui op vermenging van moedermateriaal en/of eoliese prosesse by Helshoogte, Simonsberg and Devon Valley. 'n Styging in seevlak kon die moedermateriaal by Papegaaiberg beïnvloed het. Om meer inligting omtrent die oorsprong en moontlike vermening van moedermateriaal voor grondvorming te verkry, is die verskillende grondmonsters chemies ontleed. Kalium is In uiters belangrike voedingselement wat lootgroei en wynkwaliteit kan beïnvloed. Aangesien die gronde in hierdie studie in bestaande produksieblokke voorkom, was daar 'n goeie kans dat bemestingstowwe die chemiese samestelling kon beïnvloed. Die C horisonte van die verskillende gronde was beskou as dié wat die minste deur bemesting beYnvloedsou word en die naaste aanduiding van natuurlike grondchemiese samestelling. Die C horison K-inhoude van die gronde in die studie het egter nie gekorreleer met enige eienskap wat die moedermateriaal van die gronde met die lokale gesteentetipe kon verbind nie. By Durbanville, het beide gronde klein hoeveelhede K in die C horisonte bevat, wat die onderliggende fillietiese skalies reflekteer, maar by Devon Valley en Papegaaiberg, het die C horisonte meer K bevat as wat verwag is. Die gronde by hierdie lokaliteite word onderlê deur hornfels, wat lae hoeveelhede K bevat. Die groot hoeveelhede K in hierdie gronde dui moontlik op 'n kontaksone tussen graniet en Malmesbury gesteentes in die area. Gronde vanaf Kuilsrivier, Simonsberg en Helshoogte word onderlê deur K-ryke porfiritiese graniete wat groot hoeveelhede K in die ondergronde sou bevat. Dit was egter nie die geval nie en dit was aanvaar dat verdunning van K-arme materiaal plaasgevind het. Die oorsprong van Karme materiaal was waarskynlik vanaf hoêr-liggende sandstene, of vanaf eoliese prosesse gedurende die Cenozoikum. Alternatiewelik is K inhoude van die gronde verlaag deur lang en aanhoudende loging. 'n Semi-kwantitatiewe analise van minerale in die kleifraksie was uitgevoer om te bepaal watter minerale in die kleifraksie van die verskillende gronde teenwoordig is en om die minerale met stadia van verwering te vergelyk. Dan kon die mineralogiese samestelling in verband met moedermateriaal gebring word. Resultate het aangetoon dat al die gronde in die studie in 'n gevorderde stadium van verwering is en gedomineer word deur kaoliniet, en in sekere gronde, klei fraksie kwarts. Aangesien die primêre minerale in 'n groot mate afgebreek is, was dit moeilik om die minerale in die kleifraksie direk in verband met moedermateriaal te bring. Die voorkoms van kwarts en gibbsiet in die kleifraksie in beide gronde van Simonsberg, Helshoogte en Durbanville asook een grondvorm vanaf beide Kuilsrivier en Simonsberg, het aangetoon dat verskillende stadia van verwering gedurende grondvorming in hierdie gronde voorgekom het. Dit kan die gevolg wees van vermenging van verskillende moedermateriaal, maar kan ook verskillende periodes van verwering van dieselfde materiaal aandui. Beide gronde by Papegaaiberg, beide gronde van Devon Valley die ander gronde by Simonsberg en Kuilsrivier het slegs een fase van verwering tydens grondvorming aangedui, hoofsaaklik as gevolg van die afwesigheid van gibbsiet wanneer kwarts voorkom. Grondeienskappe, soos bepaal in hierdie studie, was ook vergelyk met lootgroei, wynkwaliteit en wynkarakter, soos verkry uit die resultate van die multi-dissiplinêre projek. Vir die meeste gronde in die studie was 'n toename in kleifraksie kaoliniet geassosieer met afname in vegetatiewe groei, algemene wynkwaliteit, asook vars vegetatiewe wynkarakter. 'n Toename in kleifraksie kwarts was geassosieer met hoër algehele wynkwaliteit. 'n Toeneme in vegetatiewe groei het ook die vars vegetatiewe karakter van die wyn positief beïnvloed. Beter vegetatiewe groei het op hoër hoogtes voorgekom en dit het gelei tot hoër wynkwaliteit vir Sauvignon blanc. Wyne afkomstig van wingerde op beide fillietiese skalies en porfiritiese graniete, was van hoër kwaliteit (Durbanville and Helshoogte), maar beide was geassosieer met lae kleifraksie kaoliniet en hoë ligging. Dit was nie moontlik om moedermateriaal direk met vegetatiewe groei, wynkwaliteit en/of wynkarakter te vergelyk nie. Wyne met die laagste kwaliteit kom egter voor op hornfels (Papegaaiberg and Devon Valley), wat beide groot hoeveelhede kleifraksie kaoliniet bevat en geleê is op lae hoogtes. Hoê vlakke van K in gronde wat groot hoeveelhede kleifraksie kaoliniet bevat kan gedeeltelik verantwoordelik wees vir lae kwaliteit wyne op sulke gronde.

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Five areas proximal to the world class Namakwa Sands heavy mineral deposit have been studied and include the farms Houtkraal Remainder Portion 2, Houtkraal Remainder, Geelwal Karoo, Graauwduinen and Rietfontein. These are locally referred to as the satellite deposits and are sub-economic occurrences. The primary objective of the study was to quantify the mineralogy and mineral chemistry, determine the provenance of the heavy mineral suite and draw a comparison between the satellite deposits and the Namakwa Sands deposit from an exploratory point of view. Methodology used to achieve the above objectives included optical microscopy, Scanning Electron Microscope (SEM), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), X- Ray Fluorescence (XRF) and Zr-geothermometry of rutile. The five satellite areas contain the same heavy mineral suite but mineral proportions differ. The total heavy mineral population (THM) are diverse and consist of ilmenite and its alteration products (hydrated ilmenite, pseudorutile and leucoxene), magnetite, hematite, spinel, rutile, tourmaline, pyroxene, amphibole, garnet, aluminosilicates, staurolite, corundum, epidote, zircon, monazite and sphene. Ilmenite and garnet are the two most dominant heavy minerals present. The valuable heavy minerals (VHM) suite consists of ilmenite, zircon, rutile and leucoxene. The mineralogy of the satellite areas and chemistry of the ore minerals (rutile, zircon, ilmenite and leucoxene) are similar to the Namakwa Sands deposit. The whole spectrum of ilmenite alteration products (hydrated ilmenite, pseudorutile, and leucoxene) is present and allowed the quantitative use of the alteration index. The indices is low (22-24%) and indicates that the surficial deposits have formed under arid to semi-arid climatological conditions which preserved the pristine character of most of the minerals. This allowed reliable provenance studies using the characteristics of most of the heavy mineral suite, which showed that the minerals were derived from a diversity of source rocks. These included mainly medium to high-grade metamorphites and felsic intrusives of the underlying Mesoproterozoic Namaqualand Metamorphic Complex and a minor contribution from the Neoproterozoic Gariep Supergroup. This relationship indicates a limited transport distance from source to depositional basin. Mineral ratios in particular the THM-VHM relationship showed that the deposits located close to the shoreline such as Geelwal Karoo, Graauwduinen and Rietfontein have a relatively low proportion of valuable heavy minerals whereas those more inland such as Houtkraal Remainder Portion 2 and Houtkraal Remainder are close to unity. Heavy mineral concentration as such is low in the satellite areas and the mechanism to increase the concentration is clearly not only a function of distance from the present shoreline but is also topographically controlled. Steep sided linear depressions channelled the unconsolidated sediments and heavy minerals were upgraded into economic concentrations by aeolian processes. The quality of the valuable heavy minerals in the satellite areas however is similar to those of the adjacent Namakwa Sands deposit. This study has demonstrated that Houtkraal Remainder is the northeasterly continuation of the red aeolian sand (RAS) associated East Mine orebody and offers the best exploration potential.
AFRIKAANSE OPSOMMING: Vyf areas proksimaal aan die Namakwa Sands swaar mineral afsetting is bestudeer en sluit in Houtkraal Remainder, Houtkraal Remainder Portion 2, Geelwal Karoo, Graauwduinen en Rietfontein. Hierdie areas word plaaslik na verwys as satelliet afsettings en is subekonomies. Die hoofdoel van hierdie studie was om die mineralogie en mineral chemie te kwantifiseer, die oorsprong van die swaar mineraal suite te bepaal asook n vergelyking te tref tussen die satelliet areas en die Namakwa Sands afsetting vanuit n verkennende eksplorasie oogpunt. Optiese mikroskopie, SEM, LA-ICP-MS, QEMSCAN, XRF en die Zr-geotermometer van rutiel is gebruik om bostaande doele te bereik. Die vyf satellite areas bestaan uit dieselfde swaar minerale maar mineral proporsies verskil. Die totale swaar mineraal populasie is divers en bestaan uit ilmeniet en ilmeniet se veranderingsprodukte (gehidreerde ilmeniet, pseudorutiel en leukokseen), magnetiet, hematiet, spinel, rutiel, toermalyn, pirokseen, amfibool, granaat, aluminiumsilikate, stauroliet, korund, epidoot, sirkoon, monasiet and sfeen. Ilmenite en granaat is die twee mees dominante swaar minerale teenwoordig. Die waardevolle swaar mineraal populasie bestaan uit ilmeniet, rutiel, sirkoon en leukokseen. Die mineralogie van die satelliet areas en die chemie van die erts minerale (rutiel, sirkoon, ilmeniet en leukokseen) is dieselfde as die van die Namakwa Sands afsetting. Die hele spektrum ilmeniet veranderingsprodukte is teenwoordig en het die kwantitatiewe gebruik van die alterasie indeks toegelaat. Die alterasie indekse is laag (22-24%) en dui aan dat die oppervak afsettings gevorm het tydens droë tot semi droë toestande wat die eertydse karakter van meeste minerale bewaar het. Deurdat die karakter van meeste minerale behoue gebly het, kon provenans studies toegepas word op die swaar mineraal suite. Provenans studies het aangedui dat die swaar minerale afkomstig is van n verskeidenheid van bron gesteentes. Dit sluit in medium tot hoë graad metamorfe gesteentes en felsiese intrusies van die Mesoproterosoïese Namakwaland Metamorfiese Kompleks met n geringe bydrae van die Neo Proterosoïese Gariep Supergroep. Hierdie verhouding dui n beperkte vervoer afstand aan vanaf die bron tot by die afsettings omgewing. Mineraal vehoudings spesifiek die totale swaar mineraal-waardevolle swaar mineraal verhoudings dui aan dat afsettings na aan die kus soos Geelwal Karoo, Graauwduinen en Rietfontien n lae inhoud van waardevolle swaar minerale het teenoor afsettings soos Houtkraal Remainder Portion 2 en Houtkraal Remainder wat meer land in is met verhoudings na aan eenheid. Swaar mineral konsentrasie is laag in die satellite areas en die meganisme verantwoordelik vir die toename in konsentrasie is nie net n funksie van die afstand van die bestaande kuslyn nie maar word ook deur topografie beheer. Steil sydige lineêre depressies kanaliseer die ongekonsolideerde sediment en swaar minerale en word opgradeer tot ekonomiese konsentrasies deur wind prossese. Die kwaliteit van die waardevolle swaar minerale in die satelliet areas is egter dieselfde as die van die aangrensende Namakwa Sands afsetting. Hierdie studie het gewys dat Houtkraal Remainder is die noordelike voortsetting van die Rooi Aeoliese Sand geassosieerde Oos Myn ertsliggam en bied die beste eksplorasie potensiaal.

This study is an account of the stratigraphic sequence, the petrography, mineralogy (microprobe investigations of orthopyroxene, clinopyroxene, olivine and plagioclase feldspar), and whole-rock major- and traceelement geochemistry of the silicate cumulates of the Upper Critical Zone in the western Bushveld Complex. Two parts of the study - an investigation of a 350m column incorporating the MG3 and UGI Footwall Units, and a comparison of two additional Upper Critical Zone profiles with a previously compiled profile between the UGI and Bastard Units - are focused on RPM Union Section in the northwestern sector of the Complex. The third part is a detailed vertical and lateral investigation of the Bastard Unit at the top of the Critical Zone, which draws on sampling and data compilation from seventeen profiles in the western limb of the Complex. The MG3 Unit (45m) is made up of a lower chromitite layer overlain by a norite-pyroxenite-anorthosite sequence while the UGlFW Unit (295m) is composed of a related series of lower chromitite layers (MG4) overlain by a pyroxenite-norite-anorthosite sequence capped by the UGI chromitite layer. These mafic cumulates display a distinctive pattern of oscillating cryptic variation in whole-rock Mg/(Mg+Fe), FeO/Ti0₂, Cr/Co and Ni/V ratios through the sequence. Sympathetic oscillations are recorded for compositions of orthopyroxene and plagioclase feldspar and eight subcycles are recognised through the UGlFW Unit. The entire sequence is characterised by the presence of small, spheroidal, embayed and irregularly shaped plagioclase grains which are poikilitically enclosed in cumulus orthopyroxene grains of both pyroxenites and norites. This texture is indicative of partial resorption of pre-existing feldspar primocrysts within the melt prior to their being incorporated into the host orthopyroxene grains. Textural, geochemical and isotopic data suggest that this sequence was built up by periodic additions of fresh, relatively primitive liquid into fractionated resident liquid, and subsequent mixing within the magma chamber. The Bastard Unit sequence, described in Chapter 4, is the last and most complete cyclic unit (c. 60m) of the Critical Zone, and its upper contact defines the boundary between the Critical and Main Zones of the Complex. This Unit can conveniently be sub-divided into a lower part, where orthopyroxene occurs as a cumulus phase, and the upper part which is composed entirely of anorthosite (Giant Mottled Anorthosite). The basal part of the Unit (≤ 18m) comprises a thin chromitite layer < O.5cm) overlain by a pyroxenite-melanorite-norite-leuconorite sequence. The basal pyroxenite is orthocumulate in character and rapidly gives way to norites and leuconorites. A distinct threefold subdivision emerges within the Giant Mottled Anorthosite which is predominantly an adcumulate which becomes orthocumulate in character at its top. Apart from minor deviations in thicknesses these lithologies are recorded over the entire strike-length covered in this study. Profiles of cryptic variation are compiled for orthopyroxene, plagioclase and whole-rock data and show that the Bastard Unit displays a characteristic pattern which is maintained throughout the western Bushveld Complex. A minor yet distinctive reversal in cryptic variation is revealed at a level which is stratigraphically variable within the lower Giant Mottled Anorthosite, and results in a double cuspate pattern. A remarkable feature of the basal Bastard pyroxenites is that although the modal proportion of mafic to felsic constituents varies systematically away from the northwestern sector, the Mg/(Mg+Fe) ratio of orthopyroxenes remains constant at 0.804 over a lateral strike distance of 171km. Within the upper part of the Unit the orthopyroxene is markedly Fe-rich and it is here that inverted primary pigeonite appears for the first time as a cumulus phase. In addition, K-feldspar, oscillatory zoned plagioclase grains and high levels of incompatible trace elements are noted at this level. On the basis of the data presented it is concluded that the Bastard Unit represents the crystallisation of a final, relatively large influx of hotter primitive liquid, with upper Critical Zone affinities, and subsequent mixing with a column of cooler (less dense) supernatant liquid which had in part hybridized with the overlying Main Zone magma. It is hypothesised that this new liquid was emplaced as a basal flow beneath supernatant liquid and that it initiated the deposition of mafic cumulates at its base. The supernatant liquid is interpreted as representing the fractionated residuum produced by crystallisation of earlier cyclic units, with plagioclase on the liquidus, and that it contained an abundance of small plagioclase primocrysts in suspension. Development of the Unit can be viewed as a two-stage process. In the lower half of the unit, chemical and physical parameters typical of the new magma dominated the crystallisation process, and resulted in cumulates very similar to other relatively complete Upper Critical Zone units. In the upper, leucocratic sequence, above a minor reversal, crystallisation was from a liquid which was the product of mixing of a minor pulse of primitive liquid with the reservoir of hybridized supernatant liquid. Although the Bastard Unit is not continuous around the entire Western limb of the Complex, it is concluded that it developed in a single, or connected, magma chamber and that its irruptive feeder zone was located in the proximal northwestern facies of the Complex.

Soil structure and its associated physical properties are essential soil components. Soil texture and mineralogy are inherent soil properties that influence soil management. This study assessed the implication of tillage, texture and mineralogy on soil sieving, aggregate stability indices and physical fractions of organic matter in soils of Eastern Cape Province of South Africa. An Iris FTLVH – 0200 digital electromagnetic sieve shaker (Filtra Vibraciόn SL Spain), was used to determine settings for sieving efficiency. Mean weight diameter (MWD), water stable aggregate (WSA), state of aggregation (SA), dispersion ratio (DR), water dispersible clay (WDC), clay dispersion ratio (CDR), clay flocculation index (CFI), and potential structural deformation index (PSDI) were aggregate stability indices evaluated to check for sensitivity in evaluating aggregate stability of soils under two tillage systems and physical fractions of carbon and nitrogen in soils of Eastern Cape Province. The T4I3P2 and T4I4P3 settings were sensitive under tillage and T4I1P4, T3I4P3 and T4I4P3 were sensitive under mineralogical considerations for sieving efficiency. The total carbon in soils under conventional tillage (CT) was 17.7 g/kg and in soils under no tillage (NT) it was 15.8 g/kg. The total carbon content in the clay fraction of soils under CT was 24.1 percent higher than the total carbon content in the clay fraction of soils under NT. The total nitrogen content in the clay fraction of soils under CT was 5.4 percent higher than the total nitrogen content in the soils under NT. The total carbon in the sandy loam (SL) textured soils was 17.4 g/kg and in the sandy clay loam (SCL) textured soils it was 17.1 g/kg. The total nitrogen in SL soils was 3.7 g/kg and in SCL soils it was 3.7 g/kg. The clay fraction had higher total carbon than other fractions in Sl and SCL soils. The higher values of nitrogen were observed in the silt fraction for SL soils and clay fraction for SCL soils. The total carbon in the soils dominated with kaolinite was 17.3 g/kg and in quartz dominated soils the value was 16.9 g/kg. The total nitrogen in the soils dominated with kaolinite was 3.7 g/kg and in the soils dominated with quartz the value was 3.7 g/kg. For soils under NT the WDC was 135.8 g/kg and for soils under CT it was 139.7 g/kg. The ASC was 72.5 for soils under NT and 92.0for soils under CT. The DR was 0.9 for soils under NT and 0.8 for soils under CT. The CFI was 0.5 for soils under NT and 0.5 for soils under CT. The CDR was 0.5 for soils under NT and 0.5 for soils under CT. The MWDw was 1.6 mm for soils under NT and 1.4 mm for soils under CT. The MWDd was 4.0 mm for soils under NT and 4.0 for soils under CT. The percent WSA > 0.25 mm was 61.7 percent for soils under NT and 56.2 percent for soils under CT. The PSDI was 55.2 percent for soils under NT and 61.15 percent for soils under CT. The SA was 43.2 percent for soils under NT and 37.89 percent for soils under CT. The WDC was 125.7 g/kg for SCL soils and 151.4 g/kg for SL soils. The CDR was 0.5 for both SCL and SL soils. The DR was 0.9 for SCL soils and 0.8 for SL soils. The CFI was 0.5 for both SCL and SL soils. The ASC was 56.2 g/kg for SCL soils and 115 g/kg for SL soils. The MWDw was 1.5 mm for SCL soils and 1.4 mm for SL soils. The MWDd was 3.6 mm for SCL soils and 3.6 mm for SL soils. The percent WSA > 0.25 mm was 53.0 percent for SCL soils and 62.5 percent for SL soils. The PSDI was 59.2 percent for SCL soils and 59.7 percent for SL soils. The SA was 33.6 percent for SCL soils and 45.2 percent for SL soils. The WDC was 313.3 g/kg for kaolinitic soils and 120.7 g/kg for quartz dominated soils. The CDR was 0.5 for kaolinitic soils and 0.5 for quartz dominated soils. The DR was 0.9 for kaolinitic soils and 0.8 for quartz dominated soils. The CFI was 0.5 for kaolinitic soils and 0.5 for quartz dominated soils. The ASC was 110.0 g/kg for kaolinitic soils and 101.7 g/kg for quartz dominated soils. The WSA > 0.25 mm was 57.3 percent for quartz dominated soils and 68.4 percent for kaolinitic soils. The MWDw was 1.6 mm for quartz dominated soils and 0.8 mm for kaolinitic soils. The MWDd was 3.6 mm for quartz dominated soils and 3.4 mm for kaolinitic soils. The PSDI was 56.3 for quartz dominated soils and 76.0 for kaolinitic soils.

Thesis (PhD)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: The Swartland region in the western Cape, South Africa, covers approximately 5000 km2 and forms part of the Pan-African Saldania Belt that represents the southernmost extremity of the Pan-African orogenic belts in southern Africa. Regional mapping of the Swartland area shows that lithologies can be classified using predominantly structural and to a lesser extent lithological criteria. This led to the proposal of a new classification, were rocks of the previous classification of the Malmesbury Group are divided into two new groups, namely the Swartland and Malmesbury groups. The Swartland group can be divided into the Berg River and Moorreesburg formations, a series of quartz-chlorite-muscovite-feldspar schists, quartz schists, graphitic schists and limestones; and the Bridgetown formation, a series of metavolcanic rocks with WPB-MORB affinities that possibly represent seafloor. Deposition of the sediments is suggested to have occurred concurrently with deformation in an accretionary prism/fore-arc and was initiated with the opening of the lapetus Ocean at ca. 600 Ma. This early deformation event, Dt (ca. 575 Ma), only affected the Swartland group and exhibits pervasive bedding transposition, thrusting and imbrication of units creating a tectonostratigraphic sequence. Where identified, kinematic indicators and fold vergence indicate a top-to-the-west transport direction during the early, low-angle Di deformation. The Malmesbury group overlies the Swartland group, being locally separated by an unconformity. The Malmesbury group is a succession of conglomerates, grits and shales (Piketberg Formation), grading into greywackes, shales, siltstones, sandstones and minor limestones of the Tygerberg and Porterville formations. Sedimentation probably commenced after ca. 575 Ma and lasted until shortly after 560 Ma. Both the Swartland and Malmesbury groups were then deformed by the deformation event, D2 (ca. 552-545 Ma), and were intruded by the 552 to 510 Ma Cape Granite Suite. The Franschhoek Formation, formally part of the Malmesbury Group is now classified, along with the inferred ca. 535-510 Ma Magrug and Populierbos Formations of the previous Klipheuwel Group. The redefined Klipheuwel group documents a change in depositional environment from the continental slope/ocean trench, marine and flyschoid deposits of the Malmesbury group to continental, fluvial half-graben and graben deposits. Exhumation, extensive erosion and the formation of a peneplain, was followed by the deposition of the Table Mountain Sandstone Group around 550-510 Ma. The Spitskop gold prospect, located 10 km south of Piketberg, represents the first identified occurrence of mesothermal gold mineralisation in the Saldania Belt. Metamorphic devolatilisation of the Swartland group during Di led to the scavenging and transportation of gold along shallow-dipping shear zones that are contained within the early, sub-horizontal So/Si tectonic fabric. Pervasive fluid movement in the Spitskop area led to elevated gold values compared to background values throughout the lithologies at Spitskop. The lack of any economic-grade gold mineralisation is probably related to the absence of suitably orientated structures, such as high-angle faults, that are commonly believed to represent the prerequisite for large fluid throughputs that could result in economic-grade gold deposits. The mineralisation at Spitskop, however, provides a genetic model for further exploration of gold in the Swartland group.
AFRIKAANSE OPSOMMING: Die Swartland streek in die Wes-Kaap, Suid-Afrika, beslaan ongeveer 5000 km2 en vorm deel van die Pan-Afrikaanse Saldania-gordel wat die mees suidelike deel van die Pan-Afrikaanse orogene gordels in suidelike Afrika verteenwoordig. Regionale kartering van die Swartland streek dui aan dat die gesteentes geklassifiseer kan word deur oorwegend strukturele, en tot 'n mindere mate litologiese kriteria te gebruik. Gevolglik word ‘n nuwe klassifikasie voorgestel, waar gesteentes volgens die vorige klassifikasie van die Malmesbury groep verdeel word in twee groepe, naamlik die Swartland en Malmesbury groepe. Die Swartland groep kan verdeel word in die Bergrivier en Moorreesburg formasies, ‘n reeks kwarts-chloriet-muskoviet-veldspaat skis, kwarts skis, grafitiese skis en kalksteen; en die Bridgetown formasie, ‘n reeks metavulkaniese gesteentes met WPB-MORB affiniteite wat moontlik oseaanvloer verteenwoordig. Daar word voorgestel dat afsetting van die sedimente gelyktydig plaasgevind het saam met vervorming in ‘n akkresionere prisma/voorboog, geinisieer deur die opening van die lapetus Oseaan (ca. 600 Ma). Hierdie vroee vervorming, Di (ca. 575 Ma), het slegs die Swartland groep geaffekteer en vertoon deurdringende verplasing van gelaagdheid, oorskuiwing en imbrikasie van eenhede en het ‘n tektonostratigrafiese opeenvolging gevorm. Waar identifiseer, dui kinematiese aanwysers en plooi kanteling op ‘n bokant-na-wes beweging gedurende die vroee, lae hoek Di vervorming. Die Malmesbury groep oordek die Swartland groep, plaaslik geskei deur ‘n diskordansie. The Malmesbury groep bestaan uit ‘n opeenvolging konglomeraat, grintsteen en skalie (Piketberg formasie), wat gradeer in grouwak, skalie, sliksteen, sandsteen en ondergeskikte kalksteen van die Tygerberg en Porterville formasies. Sedimentasie het waarskynlik begin na ca. 575 Ma en het voortgeduur tot kort na 560 Ma. Beide die Swartland en Malmesbury groepe is hierna vervorm deur D2, (ca. 552-545 Ma) en daaropvolgend ingedring deur die 552 tot 510 Ma Kaap Graniet Suite. Die Franschhoek Formasie, voorheen deel van die Malmesbury Groep, word nou geklassifiseer tesame met die afgeleide ca. 535-510 Ma Magrug en Populierbos formasies as deel van die voorheen geklassifiseerde Klipheuwel groep. Die hergedefinieerde Klipheuwel groep dui op 'n verandering in afsettingsomgewing vanaf die kontinentale glooiing/oseaantrog, mariene en flyschoiede afsettings van die Malmesbury groep na kontinentale, fluviale half-graben en graben afsettings. Herblootstelling, omvattende erosie en die vorming van ‘n skiervlakte is gevolg deur die afsetting van die Tafelberg Sandsteen Groep random 520-510 Ma. Die Spitskop goudvoorkoms, 10 km suid van Piketberg, verteenwoordig die eerste identifiseerde voorkoms van mesotermale goudmineralisasie in die Saldania Gordel. Metamorfe ontvlugtiging van die Swartland groep gedurende Dt het aanleiding gegee tot die roofuitruiling en vervoer van goud langs laaghellende skuifskeursones in die vroee, subhorisontale S0/Si tektoniese maaksel. Deurdringende vloeistofbeweging in die Spitskop omgewing het aanleiding gegee tot verhoogde goudwaardes in vergelyking met agtergrond waardes dwarsdeur die litologiee by Spitskop. Die gebrek aan ekonomiese graad goud mineralisasie is waarskynlik verwant aan die afwesigheid van geskikte georienteerde strukture, soos hoe hoek verskuiwings, wat oor die algemeen beskou word as ‘n voorvereiste vir die toevoer van groot hoeveelhede vloeistof wat kon aanleiding gegee het tot ekonomiese graad goudafsettings. Die mineralisasie by Spitskop verskaf egter 'n model vir verdere goud eksplorasie in die Swartland groep.

In the Middelplaats mine area of the Kalahari manganese field, two drill holes (MP53 and MP54) intersected anomalously high-grade manganese ore sitting stratigraphically just above an igneous body (likely a dike or sill). Manganese ore located within approximate 5 meters of the contact with the underlying igneous rocks has been substantially metasomatically upgraded from 25 percent manganese, to over 40 percent whilst the dominant manganese species within the ore has been altered to hausmannite. This report demonstrates the metasomatic alteration is related to devolatilization (removal and/or remobilization of H₂O, CO₂ and CaO) due to contact metamorphism caused by the underlying igneous rocks. The Middelplaats mine is situated in the southwest corner of the Kalahari manganese field where the paleo basin shallows out and ends. Within the mine area, several stratigraphic units pinch out or are truncated by the side of the basin. This pinching out of lithological formations has led to the underlying Ongeluk Formation being in contact with the much younger units of the Hotazel Formation. Therefore, geochemical investigation into the nature and source of the igneous rocks was also undertaken to see if the rocks from the two drill holes were related to one another and/or the underlying Ongeluk Formation. Results of these geochemical studies have demonstrated that the Middelplaats igneous rocks (dolerites) from the two drill holes (MP53 and MP54) share a co-genetic source region. There is also reasonable geochemical evidence that the source region of the Middelplaats igneous rocks was substantially similar to the source region of the Ongeluk Formation. This may indicate that the source region of the Ongeluk Formation was reactivated at some later stage resulting in the emplacement of doleritic dikes or sills in the Middelplaats mine area. The Middelplaats igneous rocks were also found to have undergone a slight but pervasive potassic alteration; with most of the original plagioclase feldspar showing some level of replacement by a potassium enriched feldspar. Although no source for this potassic fluid was found, the devolatilization reaction within the manganese ore appears to have released some potassium into the surrounding rocks. This additional potassium may be responsible for some localized potassic alteration.

Several disequilibrium textures are found to occur within the hanging wall and footwall of the UG2 chromitite layer of the Bushveld Complex, South Africa. These textures include plagioclase chadacrysts found included within orthopyroxene and clinopyroxene as well as the orthopyroxenes exhibiting round crystal boundaries that appear to be resorbed. Textures found within the UG2 stratigraphy such as linear boundaries and 120° triple junctions at interfaces of adjacent plagioclase or pyroxene grains also suggest that recrystallization has taken place. The presence of both disequilibrium textures and recrystallization textures would suggest that a complex emplacement history has occurred. Ideally, this would be expected to be manifested by minerals of the same type but which are texturally distinct showing different composition. However this has been found not to be the case; minerals that suggest disequilibrium textures show similar compositions to the minerals which appear to have formed in equilibrium. This is also the same for recrystallized crystals which show the same compositions as crystals that have not been recrystallized. For example tabular clinopyroxene, which has a compositional range of En 44.6 to En 50.5, is indistinguishable from clinopyroxene occuring as discontinuous rims, En 44.3-48.2, and as intergranular necking connecting primocrysts of orthopyroxene ( En 44.3-50.4). Similarly, plagioclase occurring as inclusions with An 66.3-76.0 is indistinguishable from plagioclase occurring as zoned or recrystallized interstitial grains ( An 69.0- An 77.4). Compositional variation has however, been found to be controlled to an extent by stratigraphy in that minerals show different compositions within one layer to the same minerals within another layer, consistent with an evolving magma composition. It is concluded therefore that while composition is not texturally controlled it is to an extent stratigraphy controlled and that the evidence collected within the study supports two models for the formation of chromite within the Bushveld complex. The evidence is consistent with a combination of the magma mixing model and magma injection model to account for the textures and compositional variations found within the study. The evidence may also show support for models involving late modification of minerals by magmatic fluids but not as prominently as for the models mentioned above
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>Magister Scientiae - MSc
The present research deals with the characterization of the Lower Ecca Group in terms of sedimentology, mineralogy and organic geochemistry. A field study was conducted in order to characterize the sedimentology and thereby determine the environments of deposition of the Prince Albert, Whitehill and Collingham Formations. In addition, shale samples were subjected to geochemical and mineralogical analyses so as to ascertain its source rock properties. The study utilized X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS), total organic carbon (TOC) and Rock-Eval pyrolysis to determine the mineralogy and organic geochemistry of shale from the formations under investigation. The sedimentological investigation revealed that the upper Prince Albert Formation is dominated by shale with thin beds of carbonate. These shales are interpreted to have been deposited by suspension settling in a marine environment which was occasionally interrupted by deposition of carbonates that form in a shallow marine environment. The overlying Whitehill Formation consists predominantly of carbonaceous shale with relatively more resistant shale beds also present. The fine sediments are interpreted to have been deposited from suspension settling under anoxic bottom conditions which would favor the preservation of organic rich material. Deposition of the Whitehill Formation was followed by the Collingham Formation which is dominated by rhythmic deposits of shale and sandstone that are occasionally interrupted by tuff layers. The clay size sediments are interpreted to have been deposited from suspension settling which are interbedded with low density turbidite current deposits in a marine environment. Based on the findings of the field study, it is apparent that the Prince Albert and Collingham Formations were deposited in marine environments, with the Whitehill Formation being deposited in an anoxic environment. These environments are known to be dominated by phytoplanktonic organisms and algal debris, and as such shales deposited in these environments contain predominantly Type I (derived from algae) and II kerogen (derived from plankton). It can therefore be postulated that Type I and II kerogens are the dominant constituents of organic matter in the Lower Ecca Group shales. Mineralogically, the shales consist chiefly of kaolinite, smectite and illite clay minerals, which are derived from a combination of weathering of feldspars, and the alteration of other clay minerals. The latter being inferred from the existence of albite in all the studied shale samples, pyroclastic material observed in the field, as well as the occurrence of alteration along clay mineral edges.

Philosophiae Doctor - PhD
Investigation of the acoustic impedance variations in the upper shallow marine sandstone reservoirs was extensively studied from 10 selected wells, namely: F-O1, F-O2, E-M4, E-CN1, E-G1, E-W1, F-A10, F-A11, F-A13, and F-L1 in the Bredasdorp Basin, offshore, South Africa. The studied wells were selected randomly across the upper shallow marine interval with the purpose of conducting a regional study to assess the variations in the acoustic impedance across the reservoirs using wireline log and core data. The datasets used in this study were geophysical wireline logs, conventional core analysis, geological well completion reports, core plugs, and core samples. The physical rock properties such as lithology, fluid type, and hydrocarbon bearing zone were identified while different parameters like the volume of clay, porosity, and water saturation were quantitatively estimated. The reservoirs were penetrated at a different depth ranging from a shallow depth of 2442m at well F-L1 to a deeper depth of 4256.7m at well E-CN1. The average volume of clay, average effective porosity from wireline log, and average water saturation ranged from 8.6%- 43%, 9%- 16% and 12%- 68%, respectively. Porosity distribution was fairly equal across the field from east to west except in well F-A10, F-A13, and F-A11 where a much higher porosity was shown with F-A13 showing the highest average value of 16%. Wells E-CN1, E-W1, F-O1, F-L1 and E-G1 had lower porosity with E-CN1 showing the lowest average value of 9%. The acoustic properties of the reservoirs were determined from geophysical wireline logs in order to calculate acoustic impedance and also investigate factors controlling density and acoustic velocities of these sediments. The acoustic impedance proved to be highest on the central to the western side of the field at E-CN1 with an average value of 11832 g/cm3s whereas, well F-A13 reservoir in the eastern side of the field proved to have the lowest average acoustic impedance of 9821 g/cm3s. There was a good linear negative relationship between acoustic impedance and porosity, compressional velocity vs porosity and porosity vs bulk density. A good linear negative relationship between acoustic impedance and porosity was obtained where the reservoir was homogenous, thick sandstone. However, interbedded shale units within the reservoir appeared to hinder a reliable correlation between acoustic impedance and porosity. The cross-plots results showed that porosity was one of the major factors controlling bulk density, compressional velocity (Vp) and acoustic impedance. The Gassmann equation was used for the determination of the effects of fluid substitution on acoustic properties using rock frame properties. Three fluid substitution models (brine, oil, and gas) were determined for pure sandstones and were used to measure the behaviour of the different sandstone saturations. A significant decrease was observed in Vp when the initial water saturation was substituted with a hydrocarbon (oil or gas) in all the wells. The value of density decreased quite visibly in all the wells when the brine (100% water saturation) was substituted with gas or oil. The fluid substitution affected the rock property significantly. The Vp slightly decreases when brine was substituted with water in wells F-A13, F-A10, F-O2, F-O1 F-A11, F-L1, and E-CN1. Wells E-G1, E-W1, and E-M4 contain oil and gas and therefore showed a notable decrease from brine to oil and from oil to gas respectively. Shear velocity (Vs) remained unaffected in all the wells. The acoustic impedance logs showed a decrease when 100% water saturation was replaced with a hydrocarbon (oil or gas) in all the wells. Clay presence significantly affects the behaviour of the acoustic properties of the reservoir rocks as a function of mineral type, volume, and distribution. The presence of glauconite mineral was observed in all the wells. Thirty-two thin sections, XRD and SEM/EDS from eight out of ten wells were studied to investigate lithology, diagenesis and the effect of mineralogy on porosity and acoustic properties (Compressional velocity and bulk density) within the studied reservoir units. Cementation (calcite and quartz), dissolution, compaction, clay mineral authigenesis, and stylolitization were the most significant diagenetic processes affecting porosity, velocity, and density.Well E-CN1 reservoir quality was very poor due to the destruction of intergranular porosity by extensive quartz and illite cementation, and compaction whereas well F-A13 show a highly porous sandstone reservoir with rounded monocrystalline quartz grain and only clusters of elongate to disc-like, authigenic chlorite crystals partly filling a depression within altered detrital grains. Overall, the results show that the porosity, lithology mineralogy, compaction and pore fluid were the major factors causing the acoustic impedance variations in the upper shallow marine sandstone reservoirs.
2021-09-01

The UG3 at Modikwa Platinum Mine occurs as a platiniferous, planar chromitite seam. It is stratigraphically located in the Upper Critical Zone of the Eastern Bushveld Complex. Field work study comprise of underground mapping, sampling, surface mapping, borehole core logging, microprobing and microscopic investigations carried out at the Rhodes University. The UG3 at the Modikwa Platinum Mine is about 22cm thick chromitite seam underlain by a white fine grained anorthosite and overlain by a brown medium grained feldspathic pyroxenite. It is an incomplete cyclic unit consisting of chromite and feldspathic pyroxenite. The UG3 reef at the Modikwa Platinum Mine lease area represents a Platinum Group Metal resource of 300 million tons of ore at an in situ grade of 2.5g/t. Under the current market conditions the UG3 reef remains unprofitable to mine in an underground operation due to the operational cost involved. However, it has been illustrated that the UG3 chromitite seam can increase profit margins in an open pit operation provided it is mined together with the economic UG2 chromitite seam. The extraction of the UG3 as ore in the four Modikwa UG2 open pits would result in a combined operating cash profit of R330 million. The UG3 chromitite seam is platiniferous. The platinum-group minerals (PGM) range in size from less than 10μm to about 70μm. The PGMs are associated with sulphides and are both located in the interstitial silicates and are concentrated in the chromitite seam. The PGMs show a strong preference to contact boundaries of the silicate grains, the chromite grains and the sulphide phases. In some instances, they are enclosed within the chromite grains in association with sulphides. The general sulphide assemblage comprises pentlandite and chalcopyrite whereas, the PGMs assemblage comprises cooperite, ferroplatinum, laurite, FeRhS and PtRhS.

Thesis (MSc.)--Stellenbosch University, 1994.
ENGLISH ABSTRACT: The NAD deposit forms part of the A-Mine Complex in the Rooiberg tin field in the north-western Transvaal. Mining started in 1986 and the mine was closed recently following a decline of tin prices and metallurgical problems with ore recovery. The deposit is hosted by the Boschoffsberg Quartzite Member of the Pretoria Group sediments and is structurally controlled within the so-called Tin Zone. Extensive alteration of the original host rocks occurred during the mineralisation event. Potassic remobilisation and redistribution appear to have taken place pervasively. The nature of the original host rock was altered to such an extent that it cannot be classified correctly. Previous workers refer to the host rock as an arkose because of its feldspathic nature. Wall rock alteration in the hanging- and foot wall of the different ore lodes (fractures) is generally similar. Very little change is observed in whole rock chemistry away from the lodes. The mineral chemistry of the ore lode minerals is indicative of fluid composition and mineralising conditions in the NAD deposit. The FeO/(FeO + MgO) ratio of tourmalines indicates deposition at a distance from the source of the mineralising fluids. Pyrite trace element chemistry differs from that of the Leeuwpoort deposit, indicating changing fluid chemistry. Contrary to previous assumptions that the carbonate present is ankerite, abundant siderite occurrences were found. Pyrite may co-precipitate with siderite under specific physico-chemical conditions. Cassiterite is generally trace element poor and relatively enriched in Fe. Hydraulic brecciation of the fractures as well as the tourmaline chemistry are strong indicators of a hydrothermal origin for the NAD deposit. However, the origin of the hydrothermal fluids is still uncertain.
AFRIKAANSE OPSOMMING: Die NAD- tinafsetting vorm dee/ van die A-Myn-kompleks in die Rooiberg tinveld in die noord-wes Transvaal. Die myn is in 1986 geopen en is onlangs gesluit weens swak tinpryse en metallurgiese ertsherwinningsprobleme. Die tinafsetting kom voor in die Boschoffsberg Kwartsiet lid van die Pretoria Groep sedimente. Dit is strukturee/ gekontroleer binne die sogenaamde Tin Sone. Vorige navorsers het na die waardgesteente as 'n arkose verwys op grand van die hoe veldspaat-inhoud. lntensiewe en uitgebreide verandering van die oorspronklike waardgesteentes het plaasgevind tydens mineralisasie. Deurdringende kalium-hermobilisering en -herverspreiding het plaasgevind. Die aard van die oorspronklike waardgesteente is egter tot so 'n mate verander, dat dit chemies nie korrek gek/assifiseer kan word nie. Wandrotsverandering van die verskil/ende ertsskeute in beide die voet- en dakgesteentes is baie soortge/yk. Die heelrotsgeochemie van die wandgesteentes verskil baie min weg van die ertsskeute af. Die mineraalchemie van die ertsskeut-minerale is aanduidend van die v/oeistofsamestelling en mineralisasietoestande van die NAD-tinafsetting. Die FeO/(FeO + MgO) verhouding van toermalyne dui daarop dat afsetting op 'n afstand vanaf die bron van die mineralisasie-vloeistowwe plaasgevind het. Die spoor-elementchemie van die NAD-piriete verskil van die piriete van die Leeuwpoort tinafsetting, wat verandering in vloeistofsamestelling aandui. In teenstelling met vorige aannames dat die karbonate in die Rooiberg tinafsettings as ankeriet bekend staan, is daar volop sideriet gevind. Piriet kristalliseer dikwels saam met sideriet onder spesifieke fisiese en chemiese toestande. Kassiteriet is meestal arm aan spoor-elemente, maar is relatief verryk in Fe. Hidroliese breksiering van die skeute en die toermalyn-chemie dui sterk op 'n hidrotermale oorsprong vir die NAD afsetting. Die bron van die vloeistowwe is nog nie definitief vasgestel nie.
Digitized at 300 dpi Colour PDF format (OCR), using ,KODAK i 1220 PLUS scanner. Digitised, Ricardo Davids on request from IBL 10 September 2013

The base metal massive sulfide deposits of the Aggeneys-Gamsberg (A-G) District are hosted within the Mesoproterozoic Bushmanland Group of the Namaqua-Natal Metamorphic Complex in the Northern Cape Province of South Africa. The district displays an apparent eastward trend in the economic concentration of base metals (+ barite) from relatively Cu-Pb-rich, Ba-poor mineralisation at Black Mountain to Zn- and Ba-rich ores at Gamsberg. Base metal sulfides at Gamsberg are restricted to the so called Gams (Iron) Formation which comprises a sulfidic mineralized unit (“B”) enveloped within a sequence of meta-sedimentary units (“A” and “C”). The aim of the study was to shed further light on the genesis and chemical evolution of the sulfide mineralisation at Gamsberg in the context of the entire A-G District, by interrogating further the apparent district-wide trend in base metal distribution. The Gams Iron Formation was sampled and studied from one key drill core intersection (“G1”) which intersects the largest part of it as described elsewhere; a small number of additional samples from a second drill core (“G2”) complemented the main sample suite. Minerals that make up the silicate assemblages across the studied section include quartz, garnet, pyroxene, pyroxenoid, phyllosilicates, carbonates, amphiboles, oxides (chiefly magnetite) and graphite. In a stratigraphic context, the mineralogical variations conform directly to those documented in the relevant literature from the Gamsberg locality. These are coupled, where possible, with mineral-chemical profiles of selected silicate species which replicate those of bulk-rock compositions, particularly with respect to Mn, Fe and Ca in the upper C Unit of the studied section. These signals collectively track the characteristic transition from a terrigenous, siliciclastic sediment-dominated footwall to an exhalative sediment-dominated hanging wall to the sulfide mineralisation as also seen in similar deposits elsewhere, particularly with respect to the characteristic Mn-rich signature increasingly observed in the hanging wall C Unit. The foregoing suggests that the examined section faithfully records the interpreted primary stratigraphy of the deposits, despite the complex structural and metamorphic overprint that characterises the region. This facilitates a stratigraphic analytical approach on the sulfidic Unit B, through a combination of mineral-chemical and stable isotope analyses. Dominant sulfides in Unit B are sphalerite and pyrite, with lesser pyrrhotite and minor galena. Sphalerite shows high and generally invariant contents of Fe (mean 12.18wt%, as FeS) whereas Zn anti-correlates with Mn (mean 5.58wt%, as MnS). Isotopic analyses for S, Fe and Zn in hand-picked sphalerite and pyrite separates were used with a view to providing new evidence for chemical and isotopic variation within the sulfide ore-body in a vertical (i.e. stratigraphic) sense, discuss the implications thereof, and ultimately interpret the new data in light of similar existing data from the A-G District and elsewhere. The δ³⁴S data for pyrite (plus a single pyrrhotite grain) and sphalerite from both cores G1 and G2 show comparable compositional ranges between 22.9 and 30.4‰ and between 27 and 30.1‰ respectively. The δ⁵⁶Fe data for pyrite show a range between -1.85 and 0.19‰, whereas seven sphalerite separates have a very narrow range of δ⁶⁶Zn from 0.06 to 0.20‰. The atypically high sulfur isotope data reported in this study are interpreted to reflect sedimentary deposition of primary sulfide ore at Gamsberg from an isotopically highly evolved seawater sulfate source through large-scale Rayleigh fractionation processes. Thermogenic sulfate reduction is proposed to have been the main reductive mechanism from seawater sulfate to sulfide, given the absence of very low δ³⁴S data for sulfides anywhere in the A-G District. By contrast, the δ⁶⁶Zn values for sphalerite are for all intents and purposes invariant and very close to 0‰, and therefore suggest little Zn isotope fractionation from an original exhalative fluid source. On this evidence alone, Zn isotopes therefore appear to hold little promise as a proxy of the chemical and isotopic evolution of SEDEX deposits in space and time, although this can only be verified through further application in the broader A-G District and similar deposits elsewhere. The apparent decoupling of Zn and S isotopes in the Gamsberg sulfide deposit, however, points towards diverse sources of these two components, i.e. ascending metalliferous brines versus seawater respectively. Finally, pyrite δ⁵⁶Fe data do show a stratigraphic trend of generally declining values up-section, which are interpreted to reflect the influence of broadly coeval precipitation of isotopically heavy Fe-oxides on a broader-scale – now preserved as abundant magnetite through metamorphism. Further work on the iron isotope composition of silicate-and oxide-hosted Fe on a local-to-district scale will assist in testing this interpretation.

The Grootegeluk Formation in the Waterberg Coalfield consists of coal and mudstone layers that were deposited during the Late Permian. In the south-central part of the Waterberg Basin rapid subsidence resulted in the formation of strata (-70 m thick) which consist of relatively thin coal beds interbedded with a multitude of mudstone and carbonaceous mudstone layers. Mudstones from the Grootegeluk Formation, the underlying upper Vryheid Formation and the base of the overlying Beaufort Group were obtained predominantly from borehole cores. The thesis integrates thin-section petrography, mineralogy, maceral composition, maximum vitrinite reflectivity and geochemical analyses to investigate: (1) the source of the sediments and the palaeo-environment of formation of the coal and mudstone layers; (2) the stratigraphical correlations of some South African coal formations and the formation of coal, on a continental scale, during the Late Permian and Triassic times; (3) the possibility of contamination to the environment by the waste products of coal-mining ( carbonaceous mudstones) and coal-burning in a local power-station (fly ash and bottom ash). The lower portion of the Grootegeluk Formation is dominated by kaolinite, quartz and minor amounts of anatase, and the upper parts of by quartz, kaolinite and minor amounts of montmorillonite-illite and microcline. These minerals are predominantly allogenic. Mineralogical evidence from the mudstones suggests that the base of the Grootegeluk Formation was relatively more distal and the upper portions more proximal to the source of the sediments. The maceral variation of the coal seams and the organic matter in the mudstones reveal that conditions for the preservation of organic matter were more suitable during the deposition of the sediments in the upper (vitrinite-rich) rather than the lower (inertinite-rich) Grootegeluk Formation. At the base of the Grootegeluk Formation a 2 m thick carbo-tonstein occurs that is dominated by kaolinite, organic matter (-40 weight %), siderite, calcite and minor proportions of apatite. The carbo- tonstein has mineralogical, maceral and chemical characteristics distinctive from the other mudstones. Syn-depositional calcite lenses occur predominantly in the upper-half of the Grootegeluk Formation. Early diagenetic globular pyrite and spherulitic siderite occur in the coals and organic rich-mudstones of the Grootegeluk Formation. Globular pyrite and granular siderite are present predominantly in the organic-poor mudstones of the Grootegeluk Formation and Beaufort Group. Marcasite sometimes occurs along bedding planes and calcite is generally present as deat-filling in the coal seams. Based on their geochemistry, the Grootegeluk Formation and Beaufort Group mudstones have the same provenance, dominantly "granitic", possibly granodioritic in composition (Late Proterozoic Sm-Nd model ages). The provenance of the Vryheid Formation was relatively more mafic (Early Proterozoic Sm-Nd model ages). Smooth, systematic changes in the mineralogy and major element chemistry make major element whole-rod chemistry an ideal stratigraphic-indicator tool for the Grootegeluk Formation. The mudstones had very low concentrations of the alkali and alkaline-earth elements suggesting that the rocks had undergone very high degrees of chemical alteration. Trace elements in the carbonaceous mudstones are predominantly hosted in the mineral fraction. The carbo-tonstein had anomalously high concentrations of all the trace elements except S, Co, As and Zn, which, in addition to its mineralogical character, make the carbo-tonstein an important ( chrono-) stratigraphic marker for local and intra-basinal correlation. Anomalous concentrations of the chalcophile elements in the mudstones from the overlying lower Beaufort Group mudstones are considered to have been concentrated as a result of diagenesis and(or) reduction-oxidation reactions. The concentrations of trace elements and stable isotope data suggest that the sediments were deposited in fresh rather than in marine waters. Evidence from organic 13 C analyses and palynological studies indicates that ~ 13 C values can be used in stratigraphical correlations and as palaeo-ecological indicators. The ~ 13 C values of the Permian and Triassic terrestrial organic matter suggest a change in the atmospheric 13 C/1 2 C ratio during this time. Leachable concentrations of trace elements which may be toxic to plants, animals or humans are too low in coal mining discards to be of any concern. Mudstones that immediately overlie the Grootegeluk Formation coal-mudstones have leachable concentrations of elements that exceed the critical concentrations believed to be harmful to the environment. Experiments on fly ash and bottom ash samples from the Matimba power station revealed that the fly ash had unacceptably high concentrations of leachable elements, such as As, Cd and Mo. Leachates of bottom ash samples had very low concentrations of potentially harmful elements.

Aggregate stability and aggregate size distribution on soil surface that is impacted by rain drops affect soil erosion yet little is known about less weathered coarse textured soils. The objectives of the current study were to determine (i) the aggregate stability and associated aggregate fraction size distribution and (ii) the impact of the initial aggregate size on the aggregate stability and the resulting sediment fraction size distribution following rain drop impact in some quartz dominated coarse textured soils in the Eastern Cape Province. Soil samples for this experiment were collected from 14 ecotopes on the surface with a natural slope between 7.5 to 11% and at the depth between 0 to 0.2 m in the Eastern Cape Province. In each ecotope, twenty-five different spots were sampled using a spade at depth 0 to 0.2 m in other to eradicate biasness and ensure homogeneity. Thereafter, the soil samples were mixed to make a composite sample. The composited soil samples were then placed in rigid containers and taken to the soil science laboratory of the University of Fort Hare, Alice Campus where analyses were carried out. The soil properties were determined by passing the < 5 mm soil sample through a 2 mm sieve. The total Na, Ca and Mg contents in the soil samples were also determined using the wet digestion with sulphuric acid method. The total Soil organic matter content (SOM) was determined by the process known as weight loss on ignition. Thereafter, the fraction size distribution and aggregate stability was done by passing < 5 mm soil samples through a 3 mm sieve. The obtained calibrated aggregates between 3 and 5 mm were oven dried at 40o C. Thereafter, five gram (5g) of oven dried calibrated aggregates was immersed in a 50 mL deionized water in a 250 mL beaker for 10 minutes. The soil material left was transferred to a 0.053 mm sieve already immersed in ethanol and moved five times in the ethanol to separate < 0.053 mm from > 0.053 mm fragments. The remaining > 0.053 mm was re-immersed in ethanol and further oven dried at 40o C for 5 minutes. Thereafter, the > 0.053 mm fraction was transferred from 0.053 mm sieve, oven dried at 40o C, dry sieved using Digital Electromagnetic Shaker on a six column of sieves: 2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.106 mm, and 0.053 mm. The aggregate stability was determined using the resulting size distribution in seven classes by calculating the mean weight diameter (MWD, mm). The soils were very stable, moderately stable or unstable. The presence of smectite and cultivation as opposed to pasture lowered aggregate stability. The studied soils showed three different aggregate size distributions. Unstable soils were dominated by 0.106 – 0.25 mm aggregate size and showed a positively skewed aggregate fraction size distribution. Aggregates finer than 0.106 mm were limited because of the coarse nature of the soil texture. Moderately stable soils broke down to both micro aggregates, 0.106 – 0.25 mm and macro aggregates, 2 – 5 mm giving a bimodal distribution. The aggregate size distribution in the very stable soils was dominated by the aggregate fraction size 2 – 5 mm and a negatively skewed aggregate fraction size distribution. The smaller the initial aggregate size the higher was the aggregate stability but the reverse was true for splash erosion. It was thought that the short 5 minutes duration of the rainfall might not have been enough to cause a total breakdown of the aggregates. Alternatively, ecotopes that were dominated by primary soil minerals such as quartz showed different breakdown behaviour compared to those containing secondary minerals such as kaolinite or smectite.

>Magister Scientiae - MSc
The Platreef is known for its complexity and its heterogeneous lithologies, coupled with an unpredictable PGE and BMS mineralisation. The motivation behind this study was to aid mining geologists in targeting mineralisation irrespective of the farm. It is known that the Platreef generally overlies different footwall lithologies at individual farms. Thus, the aims of this study were firstly to investigate the potential of chemostratigraphy by delineating indices indicative of distinctive lithological layers. These indices were then tied to the second aim; which were to use geochemical vectoring, which is process-based, to target the PGEs at two different farms. This study included three drillcores: from the farms Sandsloot (SS339) and Tweefontein (TN754 and TN200). The footwall units at Tweefontein are shales of the Duitschland Formation and the Penge banded iron formation; and at Sandsloot it is the Malmani Subgroup dolomites. Samples included 121 quarter cores, used for petrographical and geochemical studies. The elemental rock composition was determined by XRF and ICP-OES analyses. The approach also included statistical and mass balance methods to understand the geological and geochemical controlling processes. Initially, the Platreef package at both farms was petrographically divided into three main layers: pyroxenite, and two distinctive feldspathic pyroxenites (FP-I and FP-II). However, the pyroxenites were also further separated as P-I and P-II, because of a higher notable difference in the degree of alteration within P-I. Progressive degrees of metasomatism were further observed in the lithologies, e.g. within the Platreef package, where feldspathisation was potentially the main metasomatic process. Many geochemical plots (corroborated by the petrographical and mass balance results) illustrated that the feldspathisation were linked to an increase in the content of Al₂O₃ and CaO, and coupled with a decrease in content of Fe₂O₃ and MgO. Together with other geochemical trends, geochemically distinct units of the Platreef package could be discriminated with a metasomatism index (MI; CaO + 10Na₂O / CaO + 10Na₂O + Fe₂O₃ + MgO). The ensuing MI is lowest for the P-II pyroxenite and shows a progressive increase through FP-I, P-I to the highest values in FP-II. Geochemical layering were also observed in the calcsilicates and hornfels; e.g. a progressive decrease in the content of Fe₂O₃, Al₂O₃, Ce, Co, Cu, Ni, Zn, Zr, Au, Pd and Pt from the hornfels subunits H-I, H-II to H-III and an increase in of SiO₂, Fe₂O₃, TiO₂, SO₃, Co, Cu, Ni, Rb, V and Zn content from CS-I, CS-II to CS-III. Correlating the pyroxenites and feldspathic pyroxenites spatially from one drillcore to another were hindered, hence, chemostratigraphy were not completed. In terms of vectoring, it was essential to establish a possible link between the metasomatism index and the nature and style of the PGE and/or BMS mineralisation. The Hornfels subunit H-I and calcsilicate subunit CS-III were the main carriers of BMS and PGE. The Platreef package were more complicated: P-I (low PGE, low BMS); P-II (low PGE, high BMS); FP-II (high PGE, low BMS); and FP-I (high PGE, high BMS). Element indices (e.g. Cu+Ni and Co+Zn) were developed to define a consistent gradient indicative of these ore subunits. A validation process to assess the metasomatism index (MI), base metal indices and PGE distribution within the individual drillcores (TN754, TN200 and SS339) were then undertaken. The results were that the MI ranges were similar in all drillcores, and discriminated the subunits of the Platreef package, gabbronorites and even the calcsilicates. The base metal ratios (e.g. Ni/Co and Cu/Co) were indicative of the PGE rich zones. Trends of the base metal ratios reflected a strong positive relationship with the MI within the Platreef package and the calcsilicates. However, the opposite trend is observed with the hornfels. In conclusion, the MI could potentially be a strong vector of high PGE and BMS mineralisation. It is also possible to discriminate lithologies within the Platreef package with the MI. However, it should be noted that the limitation of this study is that the results are based on three drillcores. The Platreef is heterogeneous at individual farms and extremely diverse across the northern limb. Therefore, future research could be undertaken to validate these findings, by using a bigger drillcore database.
National Research Foundation

Dissertation submitted in fulfilment of requirements for the degree Master of Technology: Chemical Engineering In the FACULTY OF ENGINEERING 2014
In South Africa only 5% of the coal fly ash produced annually by power stations finds use. Due to the high quantities of Si and Al in the coal fly ash researchers have explored the opportunity to use the fly ash as a feedstock in zeolite synthesis. Two principal methods have been successfully employed on a micro scale namely the 2-step method and fusion assisted method. However, in order to scale-up these processes some fundamental process design changes are required. Fly ash contains various elements including highly toxic elements such as As, Pb and Hg. The fate of these elements during the synthesis processes is not known. Both these processes generate large quantities of liquid supernatant waste. Disposal of these wastes would be expensive and environmentally harmful, thus making these processes industrially unfeasible. The well known fusion assisted process, contains an energy intensive fusion step operating at 550 C. Construction and operation of a furnace to implement fusion would be too expensive on an industrial scale. The 2-step method has a time consuming pre-hydrothermal treatment step (aging step). In order to improve the feasibility of the 2-step process the processing time of the aging step needs to be reduced. In order to breach the scale gap between micro and pilot plant scale a principal reactor design has been suggested. However, to date, no consideration has been given to the safety and operational reliability of this design. A HAZOP study is required to prevent costly incidents from occurring during the operation of this reactor. The aim of this study formed part of the overall initiative to scale-up the synthesis of zeolites to pilot and ultimately do at industrial scale. The aim of this study specifically was to perform some principal process design activities in order to prepare these processes for scale-up. The objectives were to perform material balances on the two principals synthesis approaches in order to determine the distributional fate of elements. Secondly, to make critical process design changes and develop protocols whereby the supernatant waste resulting from these processes can be minimised. Thirdly, to replace the fusion step (used in the fusion assisted process) and the aging step (used in the 2-step process) with a short high intensity sonochemical treatment step. Lastly, to perform a HAZOP study on the principal bench scale reactor design, and make design changes based on the outcome of the study. Material balances illustrated that most of the elements originating from the coal fly ash (Fe, Mn, Mg, Ca, Ti, Ba, Ce, Co, Cu, Nb, Ni, Pb, Rb, Sr, Y and Zn) do not leach out into solution during either of the two synthesis approaches. This was due to the CaO content in the ash retarding the mobility of these elements. This meant that during the 2-step process these elements reported to the overall zeolite product but did not form part of the zeolite crystal structure. On the other hand, during the fusion assisted process these elements reported to the solid residue waste. The yield efficiency of the fusion assisted process was found to be poor with only 19.6% of the Si and 21.6% Al reporting to the zeolite A product. The 2-step process on the other hand incorporated 72.2% of the Si and 81.5% Al into the zeolite product. However, the 2-step process produced a mixed phase zeolite product while the fusion assisted process produced a pure phase zeolite A product. Therefore there is a trade-off between yield efficiency and product purity. It was found that the liquid supernatant waste produced during both the synthesis processes contained toxic elements such as As, Pb, Hg, Al and Nb. This highlighted the importance to minimise the liquid supernatant waste generated. The waste minimisation studies illustrated that the liquid supernatant waste can be recycled while still producing highly crystalline zeolite products, in both the synthesis approaches. During the 2-step process the supernatant waste was recycled as a source of NaOH. By recycling the waste it was found that 40% of the supernatant could be recycled. However, by making a minor process design change a protocol was developed whereby 100% of the supernatant waste could be recycled. Also, by recycling the liquid waste, zeolite analcime became the dominant phase due to the accumulation of Si in the waste. In the fusion assisted process, protocols were developed whereby the liquid supernatant waste was recycled as a source of water. It was found that 100% of the supernatant could be recycled without compromising the relative crystallinity and purity of the zeolite A product. Both the fusion step (used in the fusion assisted approach) and the 48 hr aging step (used in the 2-step process) could be replaced with 10 min of sonochemical treatment. It was found in both cases that the introduction of ultrasound, during the pre-hydrothermal stage, increased the rate of crystal formation during the hydrothermal treatment step. It was also found that by replacing the high temperature fusion step, in the fusion assisted process, the required hydrothermal treatment temperature could be reduced to 90 C. By introducing sonochemical treatment in these two synthesis approaches their synthesis time and energy demands could be reduced successfully. A HAZOP study on the principal bench scale reactor design enabled design changes to be made preventing future loss during operation. A final optimised reactor design was proposed based on the outcome of the HAZOP study. This study effectively prepared both zeolite synthesis approaches for up-scale operation. Scale-up of this process will reduce disposal of coal fly ash offering relief to the financial and environmental strain caused to the country.

>Magister Scientiae - MSc
This study is focused on the Akanani prospect area, approximately 25 km north-west of the town of Mokopane, Limpopo Province where exploration geologists at the study area have classified the ‘pyroxenitic’ units into P1, P2, P3 and P4 units upward in order of succession with height based on their textures, mineralogy and colour. The primary aim of this study is to distinguish the distinctive geochemical and mineralogical characteristics that can be used to identify each unit (P1 to P4) and in so doing create major geochemical, petrographic and mineralogical variables that will help or facilitate the exploration for and recovery of PGE and BMS mineralisation. Geochemical and mineralogical variation studies were carried out on the cores from ZF044, ZF045, ZF048, ZF057, ZF078, ZF082 and M0023, located in the Platreef at the Akanani Prospect area on the farms Moordkopje 813LR and Zwartfontein 814LR. Using a combination of various multivariate statistical techniques (factor, cluster and discriminant analysis) and mineralogical studies (CIPW norm, microprobe analysis, petrography), the outcomes of the study have demonstrated that the Platreef at Akanani comprise at least four lithological units i.e. the basal pyroxenite portion referred to as the P1 unit comprises chromitite, pyroxenites and feldspathic pyroxenites with associated Cr, TiO2, chromite, pyroxenes, hematite and Fe2O3, the mineralized section of the P2 unit is characterized by harzburgite, serpentinized harzburgite and in places orthopyroxenites are present consistent with high MgO and LOI contents, the feldspathic portion referred here as the P3 unit is characterized by a feldspathic pyroxenite containing higher Al2O3, Na2O, K2O, albite, hypersthene and SiO2 and the top most portion of the P4 unit comprising CaO, Diopside, ilmenite, anorthite, apatite and P2O5 that can be interpreted to have formed by three separate magma pulses. Considering the possibility that the P4 unit is a hybrid melt of assimilated Platreef that interacted with intruding Main Zone magma, this reduces the number of magma pulses to two. The classification of P1, P2, P3 and P4 units of the Platreef at Akanani shows that the criteria used by mining personnel to classify the four lithological units is not definitive and therefore are not highly reliable. Although various multivariate statistical techniques were employed relatively similar elemental associations were obtained highlighiting the importance of this approach. The strongly positive correlation between sulphides, PGEs and chromite at Akanani is consistent with an orthomagmatic deposit that had been disturbed by significant hydrothermal activity, while in places a good BMS-PGE relationship is commonly associated with the main chromitite stringers in P1. Mineral and whole rock compositions of silicate rocks highlight the strongly magnesian nature of the ultramafic P2 unit. Mineral chemistry studies of chromite, orthopyroxene, olivine, clinopyroxene and plagioclase are consistent with the multi- emplacement model. Convective exchange resulted in the enrichment of iron at the bottom of the stagnant chamber, while incompatible elements migrated upwards consistent with iron depletion with stratigraphic height. Injection of P1 magma and subsequent mixing with country rocks gave rise to the formation of chromitites and addition of plagioclase component to the intruding magma. A normal fractionation trend is suggested between P2 and P3 consistent with enrichment of MgO in P2 and enrichment of Al2O3, Na2O, SiO2 and K2O in P3. The An% of 84.4 of plagioclase coupled with CaO enrichment in P4 is suggestive of some Main Zone influence and can be interpreted as resulting from partial melting and recrystallization of P3 in response to the intrusion of the Main Zone magma is suggested for the formation of the P4 unit. There exists a good correlation between the modal mineralogy and mineral chemistry as determined optically, the norm as determined by the CIPW norm and the whole-rock geochemical results as determined by multivariate statistics and conventional methods.

The main magnetite seam of the Upper Zone of the Rustenburg Layered Suite (SACS, 1980) on the Bushveld Complex is known to host the world‘s largest vanadium bearing titaniferous iron ores. The vanadiferous titanomagnetites, contain vanadium in sufficient concentrations (1.2 - 2.2 per cent V₂O₅) to be considered as resources and vanadium has been mined historically by a number of companies among them Anglo-American, Highveld Steel and Vanadium and VanMag Resources as well as currently by Evraz Highveld Steel and Vanadium Limited of South Africa. The titanomagnetites contain iron ore in the form of magnetite and titanium with concentrations averaging 50-75 per cent FeO and 12-21 per cent TiO₂. The titaniferous iron ores have been historically dismissed as a source of iron and titanium, due to the known difficulties of using iron ore with high titania content in blast furnaces. The economic potential for the extractability of the titaniferous magnetites lies in the capacity of the ores to be separated into iron rich and titanium rich concentrates usually through, crushing, grinding and magnetic separation. The separatability of iron oxides and titanium oxides, is dependent on the nature in which the titanium oxide occurs, with granular ilmenite being the most favourable since it can be separated from magnetite via magnetic separation. Titanium that occurs as finely exsolved lamellae or as iron-titanium oxides with low titania content such as ulvospinel render the potential recoverability of titanium poor. The Upper Zone vanadiferous titanomagnetites contain titanium in various forms varying from discrete granular ilmenite to finely exsolved lamellae as well as occurring as part of the minerals ulvospinel (Fe₂TiO₄) and titanomagnetite (a solid solution series between ulvospinel and magnetite) . Discrete ilmenite constitutes between 3-5 per cent by volume of the massive titanomagnetite ores, and between 5-10 per cent by volume of the magnetite-plagioclase cumulates with more than 50 per cent opaque oxide minerals. The purpose of this research was to investigate the mineralogical setting and distribution of the iron and titanium oxides within the magnetitite layers from top to bottom as well as spatially along a strike length of 2 000m to determine the potential for the titanium to be extracted from the titanomagnetite ores. The titanomagnetites of the Upper Zone of the Bushveld Complex with particular reference to the Northern Limb where this research was conducted contains titanium oxides as discrete ilmenite grains but in low concentrations whose potential for separate economic extraction will be challenging. The highest concentration of titanium in the magnetite ores is not contained in the granular ilmenite, but rather in ulvospinel and titanomagnetite as illustrated by the marked higher concentration of TiO₂ in the massive ores which contain less granular ilmenite in comparison to the disseminated ores which contain 3 to 8 percentage points higher granular ilmenite than the massive ores. On the scale of the main magnetite seam, the TiO₂ content increases with increasing stratigraphic height from being completely absent in the footwall anorthosite. The V₂2O₅ content also increases with stratigraphic height except for in one of the 3 boreholes where it drops with increasing height. The decrease or increase patterns are repeated in every seam. The titanomagnetites of the main magnetite seam display a variety of textures from coarse granular magnetite and ilmenite, to trellis ilmenite lamellae, intergranular ilmenite and magnesian spinels and fine exsolution lamellae of ulvospinel and ferro-magnesian spinels parallel to the magnetite cleavage. The bottom contact of the main magnetite seam is very sharp and there is no titanium or vanadium in the footwall barely 10cm below the contact. Chromium is present in the bottom of the 4 layers that constitute the main magnetite seam and it upwards decreases rapidly. In boreholes P21 and P55, there are slight reversals in the TiO₂ and V₂O₅ content towards the top of the magnetite seams.

Thesis (Ph.D (Physics)) --University of Limpopo, 2005
We have derived a potential model for °uorapatite Ca10(PO4)6F2, ¯tted to structure, elastic constants and vibrational frequencies of the phosphate groups, which is compatible with existing calcite and °uorite potential mod- els. We then modelled the structure and stabilities of the dry and hydrated f0 0 0 1g, f1 0 1 0g, f1 0 1 1g, f1 1 2 0g, f1 0 1 3g and f1 1 2 1g surfaces, which calculations con¯rmed the experimental dominance of the f0 0 0 1g surface, which is prominently expressed in the calculated thermodynamic morphologies. The dehydrated morphology further shows the experimental f1 1 2 1g twinning plane, while the f1 0 1 0g cleavage plane is expressed in the hydrated morphology. Molecular adsorption of water has a stabilising e®ect on all six surfaces, where the surfaces generally show Langmuir be- haviour and the calculated hydration energies indicate physisorption (73 - 88 kJ mol¡1). The chains of °uoride ions surrounded by hexagonal calcium channels can become distorted in two major ways during relaxation: either by a shortening/lengthening of the FF distances, when the channel is perpendicular to the surface, or by distortion of the CaF bonds when the channel is parallel to the surface. Both distortions occur when the channel runs at an angle to the surface. Other relaxations include compression of the calcium sub-lattice and rotation of surface phosphate groups. We have modelled adsorption of a range of organic molecules onto dif- ferent °uorapatite surfaces, due to the importance of organic/ inorganic in- teractions in biological situations. We have selected organic molecules that represent a model for the carboxylic acids, alkyl hydroxamates and those 3 that contain both the aldehyde and hydroxyl functional groups. Adhesion of these organic molecules on the surfaces has shown strong interaction between the surface's Ca ions and the molecule's oxygens, more especially the car- bonyl oxygens than any other interactions. It was found that the number of interactions between the ions of adsorbate molecule and the mineral surfaces thus contribute signi¯cantly to the exothemicity of adsorption. Further more, simulations of apatite thin ¯lms at a range of ®-quartz surfaces have shown how the strength of adhesion between thin ¯lms of ap- atite material and ceramic silica surfaces is crucially dependent upon both the orientation of the ¯lm relative to the substrate and the nature of the silica surfaces, a ¯nding that is important in a wide number of applications, from basic geological research on intergrowth of phosphate and silicate rock minerals to the search for more e®ective surgical implant materials. It was shown that although the unrelaxed quartz surface is more reactive toward the apatite ¯lm, the more regular thin ¯lm structures grown at the pre-relaxed quartz surfaces lead to more stable interfaces. Film growth at the unrelaxed quartz surface is energetically increasingly unfavorable, whereas growth at the pre-relaxed surface is calculated to continue beyond the ¯rst layer, where the adhesion energy is convergent with the layer growth of the thin ¯lm. Ad- hesion of apatite thin ¯lm on hydroxylated surfaces of ®-quartz has shown to be energetically less favourable than at dry surfaces. This was because the thin ¯lm interact mainly with the hydroxyl ions on the surface of quartz. However, the adhesion energy is still convergent with layer growth of the thin ¯lm on the hydroxylated surfaces.
National Research Foundation of South Africa (NRF), Council for Scientific and Industrial research (CSIR), and the University of the North

The ENE trending Brandberg West - Goantagab Sn-W belt is located in the Southern Kaoko Zone of the northern coastal branch of the Damara Orogen. The lithologies in this area are turbiditic and consist of three schist units separated by two marble horizons, all of which are correlated with the Swakop Group. The formations are intensely folded by at least three episodes of which the first two are coaxial and resulted in prominent, approximately N-S trending, structures. Sn and Sn-W mineralization predominantly occurs as vein and replacement type mineralization. Vein type mineralization occurs as Brandberg West, Frans Prospect, Gamigab Prospect and the Goantagab Mining Area. The vein type mineralization is accompanied by intense alteration, consisting of greisenization, sericitization, hematitization and carbonatization. Replacement-type, hematite-cassiterite mineralization, occurs in the Goantagab Mining area in the marble close to, or at the schist marble contact. Intense ferruginous alteration of the marbles in this area, is associated with veins, which terminate against, or cross cut the marble. A regional metal zonation, ranging from Sn-W mineralization with minor sulphides at Brandberg West to Sn-sulphide mineralization at Goantagab can be detected. This metal zonation is attributed to the distance of the mineral locality from the source area, with Goantagab representing a distal and Brandberg West a proximal position relative to the source area. Structural, mineralogical and geological features of the mineralization in this area suggest that processes of ore genesis may be related to anorogenic magmatism of Karoo age.

Thesis (M.S.)--Georgia State University, 2005.
Title from title screen. Beth A. Christensen, committee chair; W. Crawford Elliott, Eirik J. Krogstad, Deborah Freile, committee members. Description based on contents viewed Dec. 22, 2006. Includes bibliographical references (p. 107-112).

Bibliography: pages 161-166.
The chemical and mineral compositions are presented for 63 pulverized fuel ash (PFA) and 16 input coal samples collected from Lethabo, Duvha and Matla power stations over the period 1987-1988. Bulk chemical composition was determined by X-ray fluorescence spectrometry. The mineral concentrations were determined by semi-quantitative X-ray diffraction based on integrated counts over peak areas, with silicon used as an internal standard. The particle size distributions were determined for two sample sets from each power station with a Malvern Instruments Particle Sizer. The major phases present in the ash are glass ( 45-75% ), mullite (16-39%) and quartz (1.5-16% ). The quartz concentration decreases in PF A from fields 1 to 4 in all the stations, and is positively correlated with the SiO₂ concentration. The concentrations of glass, mullite and quartz in PFA generally vary within well defined limits which remain constant with time. An exception is the glass concentration in Duvha PFA. Spinel concentration generally decreases in concentration in PFA from fields 1 to 4, and is positively correlated with the Fe₂O₃ concentration. Of the trace elements determined, Zr, Rb and Mn generally have no or very low enrichment in concentration in PFA from fields 1 to 4. The highest enrichment factors ( > 5) were found for As, Ge and Se in Duvha PF A. The composition of the glass and ferrite spinel phases were determined by electron microprobe analysis. The glass consists of SiO₂ (21-100%) and Al₂ O₃ (0.1-49%), with significant proportions of CaO, TiO₂, Fe₂O₃ and MgO. Al₂O₃ , MgO and TiO₂ substitute for FeO in the spinel structure, with MgO substitution dominant in Duvha spinels. Chemical mass balance calculations suggest that of the elements determined for Lethabo PFA, the only one released in a significant proportion to the atmosphere is S(92% ).

Geochemical, mineralogical and tenor variation studies were carried out on the cores from UMT040, UMT064 and UMT063, located in the Flatreef on Turfspruit, in the southern sector of the Platreef. The investigation comprised three objectives (1) to identify controls on mineralisation in the upper section of the Platreef, (2) to construct a 3D PGE tenor model, and (3) to test whether the new geological interpretation on Turfspruit correlates with the eastern and western limbs of the Bushveld Complex. The above-mentioned holes were used for geochemical analyses of major and trace elements; and UMT064 was also used for orthopyroxene microprobe analyses. For construction of the tenor model, a total of 276 drill holes were used. The distance between drill holes for geochemical studies is 145 m and 175 m respectively; and for the tenor model is approximately 100 m. The outcomes of the study have demonstrated that the upper section of the Platreef comprise at least four lithological units i.e. the topmost portion of T1, lowermost portion of T1, T2 Upper and T2 Lower that can be interpreted to have been formed by four separate pulses of magma. Considering the possibility of the T2 Lower being metamorphosed calc-silicates, this reduces the number of magma pulses to three. This is supported by the mineralogy, geochemical content and tenor variations. The T1 is made up of an orthopyroxenite (feldspathic in places), the T2 Upper comprised a pegmatoidal orthopyroxenite (also feldspathic in places) and the T2 Lower is made up of a harzburgite. High grade PGE, Ni and Cu mineralisation was found to occur within two zones in the upper section of the Platreef i.e. the T1m and T2 (Upper and Lower). Mineralisation occurs in the form of base metal sulphides such as pyrrhotite, pentlandite and chalcopyrite; and PGEs are dominated by amphoterics (PGE-arsenides, tellurides, antimonides and bismuthinides). These amphoterics are associated with base metal sulphides. The sulphides in both the T1m and T2 are interstitial. PGE minerals such as michenerite, sperrylite, hollingworthite and cooperite are present in the study area. In the T2, an increase in sulphide content and PGE grades are generally associated with the presence of the “main” chromitite stringer/ seam at the contact between a feldspathic pyroxenite (T1) and the coarse-grained to pegmatoidal pyroxenite (T2 Upper). Several other chromitites might be present above and below this contact, and it has been noted that not all of those chromitites are associated with an increase in sulphide content and higher PGE grades. PGE grades were found to be higher in T2 Upper than in T2 Lower, whereas, the base metals (particularly Ni) are generally higher in T2 Lower. In the T1m, mineralisation occurs close to the contact between the feldspathic pyroxenite and orthopyroxenite, but only the orthopyroxenite hosts the sulphides. Chromitite stringers rarely occur in the T1m. Where present, they generally occur at the top of the mineralised zone. The sulphides in both the T1m and T2 are thought to have resulted from separate and different processes. Those in the T1m are thought to have resulted from a fractional segregation process, whereas the sulphides in the T2 were thought to have been emplaced in bulk or as a mush. The 3D PGE tenor model has demonstrated that the tenor in both the T1 and T2 are higher than previously thought for the northern limb of the Bushveld Complex. Tenors in the T1 reach up to 700 ppm, whereas tenors of about 1000 ppm were recorded in the T2. These tenors are comparable to the tenors measured from the sulphide melt inclusions elsewhere in the northern limb. Tenors are the highest in the northwestern part of Turfspruit and they gradually decrease towards the southeast. Both the T1 and T2 are dominated by a tenor of about 100 ppm. In the T1, a tenor of 250 ppm is dominant in the northwestern and southeastern parts of the study area, whereas in the T2 it is only dominant in the northwestern part. Vertical variation in tenors has shown that the tenors are the highest in the topmost portion of the T1 and at the top of T2 Upper (below the T1-T2 contact). The T1 has been found to be comparable with the Merensky Reef due to the following: (a) similarities with respect to major and trace element compositions of whole rock analyses; (b) Cr/MgO ratios which are greater than 80; and (c) similarities in the pyroxene content excluding the MgO/((MgO)+FeO) ratio and CaO contents; and in the PGE tenor of the sulphides. In addition, the T1 has many of the characteristics of the model proposed by Naldrett et al (2009) for the formation of the Merensky Reef in the western Bushveld. However, the differences between the T1 and the Merensky Reef were also noted i.e. the MgO/((MgO)+FeO) ratios in this study are lower (averaging 0.71) than the Mg# reported for the Merensky Reef (Mg#78-83), the upper Critical Zone (Mg#78-84) and elsewhere in the Platreef north of Turfspruit. The CaO levels (representing the wollastonite component of the orthopyroxene) at Turfspruit are higher (>2 wt %) compared to the Merensky Cyclic Unit and other parts of the northern limb where the CaO levels are below 2 wt %. This is an indication that the pyroxene composition at Turfspruit is more evolved compared to the Merensky Reef.

MESMEG
Department of Mining and Environmental Geology
Literature indicated that several mineralogical identification studies have been carried out on clays but few have focused on the characterisation of geophagic materials from South Africa. Large quantities of earth materials are consumed daily in Mashau Village, however, their mineral content and geochemical compositions had not been determined. Moreover, though the consumption of geophagic materials is very common in the village, the associated health implications had not been addressed. Thus, the main aim of the research was to mineralogically and geochemically characterise geophagic materials commonly ingested in Mashau Village and infer on possible health implications that could result from their consumption. Questionnaires were administered to geophagists in the study area with the aim of generating data on the prevalence of geophagia and the motivations for the practice. Geophagic soils and their parent rocks (for determination of provenance) were sampled and analysed for mineralogical and geochemical content. Geophagic soil samples were subjected to the following physicochemical analyses: colour, particle size distribution, pH, cation exchange capacity (CEC) and electrical conductivity (EC). An x-ray diffractometer (XRD) was used for mineralogical analysis while major oxides and trace elements abundances were determined using x-ray fluorescence (XRF) spectrometry and laser ablation inductively coupled mass spectrometry (LA-ICP-MS), respectively. Furthermore, provenance of the geophagic materials was determined using data obtained from mineralogical and geochemical analysis. Inferred health implications were based on the physico-chemical, mineralogical and geochemical data obtained. Outcomes of the questionnaire survey revealed craving to be the motivation for geophagia in Mashau Village. Although the practice seemed to be prevalent in females of certain ages, it was certainly not limited to gender, age, educational level or socio-economic status. Out of the 20 geophagic samples, 3 samples were brown, 2 had a strong brown colour and another 2 had a light olive brown colour. Other soil colours were less common, as each colour was only observed in one sample. The sand fraction dominated the samples; the clay content was low, giving the samples a sandy clay loamy texture. The pH of the soil ranged from being slightly acidic (5.4) to being slightly alkaline. The CEC values were very high ranging from 17 t0 109 meq/100 g. vii The EC values were also high (ranging from 11.2 to 245 μS/cm) indicating a high amount of soluble salts. Mineralogical analysis of geophagic soils identified quartz, microcline, plagioclase, hornblende, dolomite, muscovite, kaolinite, smectite, talc, anatase, hematite, ilmenite, chlorite and epidote with quartz and kaolinite being the dominant minerals. Actinolite, augite, chlorite, epidote, forsterite, magnetite, muscovite, plagioclase, quartz, sepiolite and microcline were the minerals identified in rock samples. Geochemical analysis for major oxides content (SiO2, TiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, K2O, P2O5 and Cr2O3) indicated that both geophagic soils and parent rocks were mainly composed of silica and alumina. Trace elements geochemistry showed a depletion of LREEs and an enrichment of HREEs in geophagic soils. The results also revealed that the REEs were enriched in the bulk fraction than in the clay fraction. Relative to the Upper Continental Crust (UCC) compositions, the concentrations of trace elements in geophagic soils were generally low. Provenance determination results showed that geophagic soils in Mashau were derived from basalts and sandstones. Majority of the samples were formed as a result of intense weathering while some were as a result of intermediate weathering. The negative health implications of the studied materials could include perforation of the colon, damage of the dental enamel and anaemia. However, geophagic materials could also be a good source of mineral nutrients and beneficial for reduction of nausea during pregnancy.
NRF

PhDENV
Department of Ecology and Resource Management
Kaolin dominated soils are common in the tropical and subtropical regions. People depend on kaolin-rich soils for agricultural production of food and fiber. The most popular of all South African soils is the Hutton form which accounts for the marvelous redness of the landscape across the Country. The apedal (structureless) soils in the group are characterised by a relatively low CEC (< 11 cmolc kg-1) reflecting oxidic mineralogy with predominantly kaolinitic assemblage. The geochemical and mineralogical composition of soil kaolin has significant implications on soil fertility, geochemical exploration and engineering properties. Despite the dominance of kaolin in these soils, little is known of their properties in the medium. The nature of kaolin minerals in soils varies with parent material, degree of weathering and pedogenic environment. Most studies conducted in South Africa on kaolins are limited to reference kaolins with little or no publication on soil kaolins, hence, this study. This research involved the evaluation of mineralogical and geochemical characteristics of oxidic soils and soil kaolins developed from four (4) selected parent rocks which were basalt, granite, arkosic sandstone, and gneiss. Soils developed from quartzite were selected as control. Representative soil samples collected from profiles developed from the different parent rocks were analysed for physico-chemical, mineralogical, and geochemical data. The mineralogical and geochemical data obtained by x-ray diffractometry (XRD), x-ray fluorescence (XRF), and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) were used in unraveling the influence of the provenance and degree of weathering on the soil characteristics. The mineralogical and geochemical data for soil kaolins were determined through XRD, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis and differential scanning calorimetry, XRF, and LA-ICPMS to establish their mineralogical and geochemical properties with respect to their parent rocks. Comparison between the soil kaolins and selected reference kaolins were also conducted. The phosphorus (P) sorption data acquired photometrically were employed to evaluate the relationship between the P sorption capacities of the soils and soil kaolins. The influence of soil properties on the fertility of the soils were assessed based on the physico-chemical (pH, particle size distribution, and electrical conductivity (EC)) and chemical (organic matter (OM) content, cation exchange capacity (CEC), available P, exchangeable cations (Ca, K, Mg, Na, and Al), and P sorption) data. The mineralogical and geochemical data for the parent rocks were obtained by XRD, optical microscopy, XRF, and LA-ICPMS. Multivariate statistical analyses were also conducted. Results showed that the dominant colour in the studied bulk soils was dusky red (31 %) followed by brown (23 %), reddish brown, yellowish red, and yellowish brown (23 %) as well as strong brown, dark brown, reddish grey, very dark greyish brown, and dark red. Soil textures were clayey to sandy loamy with OM contents between 0.41 and 4.76 %. The pH, EC, CEC, exchangeable cations, and available P values generally ranged from 5.22 to 8.38, 10.25 to 114.40 μS/cm, 2.93 to 18.30 cmol/kg, 0.03 to 13.92 cmol/kg, and <0.01 to 54.99 mg/kg, respectively. Kaolinite and quartz were the dominant phases for soils developed from basalt whereas, quartz and plagioclase were the dominant mineral phases in soils developed from granite, arkosic sandstone, and gneiss, respectively. Other minerals present in the soils were microcline, muscovite, hematite, goethite, montmorrillonite, anatase, gibbsite, chlorite, and actinolite. Geochemical compositions of the bulk soils show relative enrichment of Fe2O3, TiO2, CaO, K2O, MgO, MnO, and Na2O (except for CaO, K2O, MgO, MnO, and Na2O in soils developed from basalt). Chemical index of alteration (CIA), chemical index of weathering (CIW), and plagioclase index of alteration (PIA) values varied between 54.92 and 99.81 % which suggest low to high degree of chemical weathering. The ACN-K and A-CNK-FM diagrams for the different soils also support these observations. Trace elements were generally enriched in soils developed from basalt and gneiss (except for Rb, Sr, and Ba in soils developed from basalt), but were depleted in soils developed from granite and arkosic sandstone (except for Cr and Ta). The principal factors responsible for the mineralogical and geochemical characteristics of the soils were the parent rocks and degree of weathering. In the soil kaolins, the dominant clay mineral was kaolinite accounting for 23 to 85 wt % followed by montmorrillonite, chlorite, and gibbsite. The non-clay minerals like quartz, plagioclase, muscovite, microcline, anatase, goethite, hematite, and actinolite accounted for the remaining percentages. The soil kaolins were characterised by thin platy kaolinite particles with partially to poorly-ordered structural order. The platy kaolinite crystals have their longest dimension sizes between 0.06 and 0.25 μm. The dehydroxylation temperatures for the studied soil kaolins ranged from 425 to 475 ˚C. The SiO2/Al2O3 ratio was lowest in soil kaolins developed from basalt and higher in soils developed from granite, arkosic sandstone, and gneiss which is consistent with their mineralogy since the former have more kaolinite. Higher Fe2O3 and CEC values were obtained relative to reference kaolins which could be attributed to the presence of more structural iron in the soil kaolins as well as their smaller crystal sizes. The presence of weatherable and accessory minerals accounted for the enrichment of Co, Ni, Cu, Zn, and Pb in the soil kaolins. The kaolinite in the soils were formed by leaching and desilication of the primary minerals in the parent rocks under suboxic conditions. H-type P adsorption isotherms obtained for both the soils and soil kaolins indicated their high affinity for phosphorus by chemisorption. The average maximum P adsorption values were in decreasing order of soils developed from basalt > granite > arkosic sandstone > quartzite (control) > gneiss, respectively whereas, for soil kaolins is basalt > granite > quartzite (control) > arkosic sandstone > gneiss, respectively. Relative to other soils developed from different parent rocks, soils developed from basalt (with more clay content) had higher capacity and buffer power for P adsorption. The standard P requirements for the soils ranged from 7.78 to 92.91 mgP/kg and were classified as low based on the Langmuir model. Significant correlation between the P adsorption parameters for the soils and soil kaolins indicated that the later could be taken as a good predictor for P sorption dynamics in the soils. Electrical conductivity of the soils were taken to be negligible in interfering with plant growth. The available P values were generally below the critical level of 12 – 15 mg/kg for soils developed from basalt, gneiss, and quartzite (control) but higher in soils developed from granite and arkosic sandstone. All the soil evaluation factor (SEF) average values estimated were greater than five indicating that they are not of poor soil fertility. The correlation results between the soil properties and P sorption parameters suggest that several variables can influence the P sorption dynamics of the soil. Regression analyses further indicated that CEC, pH, OM, and clay content in the soils account for 99 % bounding P energy variation whereas, Fe2O3 accounts for 76 % P sorption maximum variation in the soils. In addition, variations in Fe2O3 and sand contents in the soils account for 96 % and 95 % maximum buffering capacity and external P requirement (EPR) variations, respectively. Models to advance the interplay between the various soil properties and P sorption parameters in the soils were developed. Mineralogical and geochemical characteristics of the soils were principally controlled by the parent rocks and degree of weathering. The soil kaolins displayed significant differences relative to reference kaolins. Langmuir model is most suited for describing P sorption in soils and soil kaolins developed from different parent rocks within the studied area. P sorption parameters for the soils can readily be obtained from the P sorption parameters of the kaolins present in them. EPR obtained and models for predicting P sorption parameters from selected soil properties developed for the various soils will improve the efficiency of routine P fertilizer applications. Iron oxide (Fe2O3) played the most crucial role in explaining the P sorption dynamics of the soils. The major contributions from this study have been: better understanding of the influence of parent rock characteristics and degree of weathering on the soil characteristics, the nature of soil kaolins and its influence on soil properties as well as P sorption dynamics in soils have been better established, and improvement of the understanding on the relationship between soil properties and P sorption dynamics in the soils.
NRF

M.Sc.
The study site for this project is New Clydesdale Colliery situated in the Witbank Coalfield, South Africa. The Witbank Coalfield is located within the northern part of the Karoo Basin where the major coal deposits in South Africa are located. Optimum ash fusion temperatures derived from coal in this region are approximately 1400°C, and higher, although temperatures above 1300°C are also acceptable. In certain coal seams the ash fusion temperatures drop well below this optimum temperature, leading at times to problems in the user industry. Ash fusion temperature which is the temperature at which the mineral matter in coal begins to soften, flow and fuse, is an important aspect relating to coal utilization but is little understood and under-studied in South Africa. The objective of this thesis is to attempt to determine what factors, mineralogical or inorganic chemical, influence variations in the ash fusion temperatures in certain coal samples. An understanding of this problem will have a bearing on the ultimate assessment of a coal for utilization purposes, in general, and ash deposition prediction in future boiler plants in particular. This study is somewhat pioneering as no detailed studies have been undertaken or published previously. Samples were collected at four sites from New Clydesdale Colliery. The sample sites were selected based on pre-existing knowledge of the ash fusion temperatures obtained from company analytical sheets. The sites were therefore representative of low and high ash fusion temperature coal. The first two sites were located in the opencast area where the No. 2 seam is actively being mined. The other two sites were located underground where mining has ceased. Conventional analyses conducted on the samples include proximate analyses, calorific values, percentage sulphur, and ash fusion temperatures. Further analyses performed included ash analyses (composition of ash), X-ray diffraction, scanning electron microscopy and petrographic studies. It was found that although complex relationships exist between ash fusion temperature and the various geological and coal parameters, positive results were obtained. These indicate a possible relationship between low ash fusion temperatures and i) finer size fractions, ii) an increase in iron content present in the form of pyrite and iii) the form in which pyrite is present, namely cleats. High ash fusion temperatures tend to correlate with i) the absence of pyrite or ii) pyrite present as framboids.

This thesis reports the results of a mineralogical and geochemical study of pans situated in the Northern Cape Province with special emphasis on the clay minerals. From east to west the depth and size of the pans increase and associated with this increased maturity the abundance of salt (halite and thenardite) and the quantity of green sediment are also enhanced. Chemically the sediments are dominated by SiO2 that also dilutes Fe2O3, K2O, Na2O, Al2O3 and MgO (when associated with dolomite) concentrations. Authigenic calcite, dolomite, analcime and loughlinite (Na-sepiolite) occur in some of the pans to the west and FTIR spectrometry indicates that all the pans host glauconite and/or celadonite. However, smectite, illite/smectite interstratification, kaolinite and/or chlorite and loughlinite only occur in some pans. The glauconite and/or celadonite does not occur as discrete mineral grains, but forms part of the fine-grained matrix common to all of the pans and no evidence of any precursor minerals were observed. The pan environment appears to present a closed, saline setting that is conducive for the direct precipitation of a mica with a chemical composition between that of glauconite and celadonite. The influence of the water-table on the formation of the glauconite and/or celadonite appears to be significant, as the highest abundance of salt is invariably associated with the position in the profile where the sediment appears to reach its most intense green colour. In the case of Koi Pan, the celadonite component of the solid solution seems to increase as the green colour intensifies. Loughlinite in Koi Pan and Brak Pan sediments also appear to be authigenic and it is suggested that it forms after precipitation of low Mg calcite that leads to Mg enrichment of the system and consequent sepiolite formation associated with minor dolomite. Thermoluminescence ages obtained from the Koi Pan sediment range between 37ka and 48ka before present at a depth of ~120cm below the surface, while for Brak Pan, at roughly the same depth, an age of between 110ka and older than 150ka before present was obtained. This may suggest different sedimentation rates in the pans or much younger ages and thus faster formation of glauconite and/or celadonite in Koi Pan since it is suggested that the mineral is authigenic.
Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

MSCAGR (Soil Science)
Department of Soil Science
The effects of tillage on soil structure and associated soil properties such as soil respiration may differ in different soils. The study determined the effects of tillage, soil texture and mineralogy in selected soil properties on different soil types. Soil samples were collected from four different sites in the Limpopo province, South Africa. The soils were classified as Glenrosa with sandy loam texture, Dundee with loamy sand, Hutton with clay, and Shortlands with clay. Glenrosa and Dundee were dominated by quartz, while Hutton and Shortlands with kaolinite. Soil samples were taken from the surface 0 – 20 cm under conventional tillage and no-till land. Soil organic matter, texture, and mineralogy were determined. The soils were wetted to activate the microorganisms and incubated for 70 days at 30℃ and soil respiration was determined using alkali trap method on a weekly basis. The study was conducted in triplicates and arranged in a completely randomized design. Data was subjected to analysis of variance using general linear model procedure of Minitab version 19. Means were compared using paired t-test at (p ≤ 0.05). The Pearson correlation coefficient (r) was used to measure the strength of linear dependence between variables. There was a significant difference in soil organic matter (p≤0.000) among all studied soils. The mean values of soil organic matter were 2.19% in Hutton, 2.0% in Shortlands, 0.54% in Glenrosa, and 0.43% in Dundee. Quartz had a strong negative linear relationship (r = -0.66) with soil organic matter while kaolinite had a strong positive linear relationship (r = 0.96). Soil respiration increased in soils dominated with quartz and decreased in soils dominated with kaolinite. The soil respiration increased by 18.95 g CO2 m-2 d-1 in conventional tillage and decreased by 13.88 g CO2 m-2 d-1 in no-tillage due to increased exposure of soil organic matter under conventional. It was concluded that less intensive tillage such as no-tillage reduces soil respiration.
NRF

M.Sc.
Certain carbonate bearing formations in the Paleoproterozoic Pretoria Group and its Griqualand West equivalent exhibit remarkable geochemical and stable isotopic signatures. The 8'3Ccarb isotopic signatures from the Duitschland and Silverton Formations exhibit large positive excursions, which seemingly coincide with a significant increase in atmospheric oxygen between 2.4 and 2.0 Ga. The Duitschland Formation with its distinctive basal unconformity is composed primarily of limestone and dolomite units, interbedded with two compositionally different shale units and quartzite. Toward the base of the formation there is a distinct conglomeratic quartzite which forms a sequence boundary above which isotopic and geochemical signatures change dramatically. Normal marine isotopic signatures characterize the lower portion of the succession while above the sequence boundari, the carbonates are enriched in "C. This enrichment, however, appears to be the result of local processes occurring within a closed basin. Furthermore it is apparent that the Duitschland Formation (with its three distinct marker beds) is the equivalent of the Rooihoogte Formation and therefore constitutes the base of the Pretoria Group. The Mooidraai Dolomite Formation which outcrops only locally in the Northern Cape Province, is characterized by fenestral and microbially laminated dolomite. The geochemical properties are relatively homogeneous with increases in the FeO and MnO concentrations, resulting from post depositional diagenesis. The stable isotope signatures of these dolomites represent normal marine signatures. There is, however, a depletion in the 813C and 8180 signatures in the ankeritic and sideritic lithofacies, which suggests that this succession was deposited from a stratified water column with respect to the total dissolved CO2. The positive 6 13C excursion present in the carbonates of the Lucknow Formation in Griqualand West, traditionally grouped with the Olifantshoek Group can be correlated with carbonates near the top of the Silverton Formation in the Transvaal area. The latter also displays distinctly positive 6 43C values. One possibility is that if these successions were deposited in closed anoxic basins and that the isotopic anomalies are the result of local processes such as fermentive diagenesis and methanogenesis. However, the close association of the carbonates with shallow marine orthoquartzites suggests that these were deposited in an open marine system and that the positive 8 !3C values reflect a shift in the composition of the ocean water at the time of deposition of the carbonates at 2.2 Ga. Other carbonates present in the Pretoria Group, namely from the Vermont and Houtenbek Formations, display normal open marine 8' 3C values of close to zero. A systematic stratigraphic compilation of all 6 43C values available from the Transvaal Supergroup indicates that two clear-cut positive 5' 3C excursions are present. These excursions were apparently short-lived and well defined and did not occur over an extended period of time as suggested by earlier studies based on global compilations with large uncertainties in radiometric ages of deposits.

Text in Afrikaans
Prospektering is een van die eerste en belangrikste stappe in die mineraalontginningsproses en dit word ondersoek teen die agtergrond van die Mineraalwet 50 van 1991, wat die belangrikste "mynwette" herroep en die Suid-Afrikaanse mineraal- en mynreg in vele opsigte op 'n heel nuwe grondslag geplaas het. Die hoofdoel met hierdie proefskrif is om prospekteerregte te sistematiseer en te bepaal of dit beperkte saaklike regte daarstel. Ten aanvang word bepaal welke aktiwiteite prospektering daarstel en welke stowwe regtens as minerale kwalifiseer. Daar word gekyk na die regte waarvan prospekteerregte dee! vorm of waaruit dit afgelei word, naamlik eiendomsreg en mineraalregte. Die afskeiding van minerale van grond, die afskeiding van mineraalregte van grondeiendomsreg en die afskeiding van prospekteerregte van mineraalregte en grondeiendomsreg, asook die inhoud van en beperkings op die uitoefening van prospekteer- en mineraalregte, word ook ondersoek. Daar word veral aangetoon dat mineraalregte nie so wyd is as wat algemeen aanvaar word nie en dat dit 6f by die af skeiding van die roerende minerale tot niet gaan of uitgeput raak 6f in eiendomsreg daarop oorgaan. Prospekteerregte word meestal verleen by wyse van prospekteerkontrakte, waarvan daar verskillende verskyningsvorme bestaan en waarvan die een wat in die Registrasie van Aktes Wet 47 van 1937 omskryf word, as uitgangspunt geneem word. Aangesien die reg om te myn ook die reg om te prospekteer insluit, word die verlening van mynregte en antler verkrygings van prospekteerregte ook behandel. Alvorens gemeneregtelike prospekteerregte egter uitgeoefen mag word, meet magtiging daarvoor by die staat verkry word. Die verlening van statutere prospekteer- en mynmagtigings het by die inwerkingtreding van die Mineraalwet 50 van 1991 grondige veranderings ondergaan wat tesame met die relevante oorgangsbepalings ondersoek word ten einde die uitwerking van die wet op prospekteerregte te bepaal. Die vereistes vir en die regsaard van die verskillende regte word ondersoek ten einde 'n oorsig van prospekteerregte daar te stel en dit vlugtig met veral Australiese reg te vergelyk. Daar word tot die gevolgtrekking geraak dat blote prospekteerregte nie beperkte saaklike regte daarstel nie.
Prospecting is one of the first and most important steps in the minerals exploitation process and is examined against the background of the Minerals Act so of 1991, which repealed the most important "mining" legislation and in many ways placed the South African mining and minerals law on a completely new basis. The main purpose of this thesis is to systematise prospecting rights and to establish whether they constitute limited real rights. It is at the outset determined which activities constitute prospecting and which materials qualify in law as minerals. The rights from which prospecting rights are derived or of which they form part, namely ownership and mineral rights, are considered. The severing of minerals from land, the severing of mineral rights from landownership and the severing of prospecting rights from mineral rights and landownership, as well as the contents of and limitations on the exercising of prospecting and mineral rights, are also examined. It is in particular shown that mineral rights are not as comprehensive as is generally accepted and that they either terminate or are exhausted upon severance of the movable minerals from the land or are converted into ownership thereof. Prospecting rights are mostly granted by way of prospecting contracts, of which different varieties exist and of which the one defined in the Deeds Registries Act 47 of 1937 is taken as the starting point. Since the right to mine includes the right to prospect, mining rights and other acquisitions of prospecting rights are also considered. Before common law prospecting rights may be exercised, however, authority to do so must be obtained from the state. Upon the commencement of the Minerals Act 50 of 1991, the granting of statutory prospecting and mining authorisations underwent fundamental changes, which are examined with the relevant transitional provisions to determine the effect of the act. The requirements for and the juridical nature of the various rights are considered in order to establish an overview of prospecting rights and briefly to compare them mainly with Australian law. The conclusion is reached that mere prospecting rights do not constitute limited real rights.
Jurisprudence
LL. D.

MENVSC
Department of Mining and Environmental Gelogy
In the present study, the physico-chemical, applications, mineralogy, geochemistry and stable isotope of Lwamondo and Zebediela kaolin is documented, in order to understand the genesis, paleoenvironmental conditions and possible utilization. Mineral identification studies were conducted using X-ray diffractometer (XRD), Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope with energy dispersive X-ray micro analysis (SEM-EDX). Major oxides were identified by X-ray Florescence (XRF) whereas trace elements were identified by Laser Ablation Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Hydrogen and oxygen isotopic composition were determined by δ18O and δD isotopic measurements. Kaolinite was dominant mineral in all the kaolin samples whereas muscovite, quartz, goethite, hematite, smectite, anatase occurred in minor to trace quantities. The chemical data show that the kaolins are composed mainly of SiO2 and Al2O3 due to the presence of quartz and kaolinite, with minor to trace amounts of other elements such as Ca, Na, Cr, K, Fe, Mn, Mg, P and Ti which affected the kaolin application negatively. Lower concentration of Ca, Na, K, Fe, Mn, Mg, and Ti show the extent of the kaolinitisation. The samples were enriched in Ni and depleted in some other trace elements. The chondrite-normalised rare earth elements patterns show enrichmnent in Heavy Rare Earth Elements (HREE) than Light Rare Earth Elements (LREE) with slight positive Eu anomaly. The Rare Earth Elements (REE) pattern and the content of other trace elements show evidence of weathering processes related to kaolinitisatioon. Kaolin genesis is explained using kaolin mineralogy, particle morphology, structural order (functional group), major and trace elements geochemical data. The data suggest that kaolin is derived from the intensive chemical weathering of intermediate to mafic rocks deposited in non-marine environment. The stable isotopes were used to determine the paleoenvironmental conditions which influenced kaolinitisation of Lwamondo and Zebediela kaolins. Stable isotopes mean values for kaolinite from both Lwamondo and Zebediela were as follows: δ18O for Lwamondo= +18.57‰ and for Zebediela = +16.67 ‰ vii and δD for Lwamondo = -65‰ and for Zebediela = -64‰. The calculated mean temperatures were 26.94 ⁰C for Lwamondo kaolin and 36 ⁰C for Zebediela kaolin. Low temperatures were inferred from stable isotope values to have been involved in the kaolinitisation wherein hydrothermal processes were eliminated. The data suggests that kaolin was formed in a weathering environment. The kaolin is found to be suitable for brick making and based on the physico-chemical, mineralogical and chemical data it was suggested that the kaolin could also be used in producing low temperature ceramics, refractory materials, pottery and stoneware

D.Phil.
This study which describes rocks of the Upper Critical Zone of the Bushveld Complex is subdivided into three parts. The main rock type of the Upper Critical Zone, the noriteanorthosite, is the subject of the first part. Inclusions in chromite and plagioclase were studied. The inclusions' in chromite were observed at different stages of their formation. The chromite crystals usually overgrow plagioclase, pyroxene and hydrous minerals (biotite, amphibole and clinozoisite) trapping them at grain boundaries or triple junctions of chromite host grains. With 'continuous growth of the host minerals the inclusion starts changing its shape from elongated to circular and the hydrous mineral proportion of the inclusion increases. Simultaneously amphibole changes its composition from pargasitic to tremolitic...

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.