Botswana covers an area of 570 000 km and has a population of about 600 000. It is estimated that three-quarters of the human and livestock populations are dependent on ground water, with an estimated 26 x 10 m of water from this source being used annually. Details of the physiography, climate, denudational and depositional surfaces and geology are given: Ground water occurs in both primary and secondary aquifers under both water-table and artesian conditions at varying depths from less than 1m to over 300m. The water-bearing properties of the various aquifers are described with the basalt/Cave sandstone contact providing the greatest number of successful boreholes and the sedimentary rocks of the Pretoria Group providing the highest yields (208,45 litres/minute). The shallowest water is found in the Kalahari Beds and the deepest in the Ecca Group. Detailed descriptions are given of the hydrogeology of the Central Kalahari, Lobatse, Orapa and Serowe. In the Lobatse area, estimates of the average monthly recharge rate have been made as well as estimates of the total storage capacity of the various ground-water basins. The percentage of annual rainfall contributing to ground water has also been calculated. An annual recharge rate has also been calculated for Serowe while the total amount of water in storage in the important Cave sandstone aquifer has been estimated. Hydrogeological details of the Kalahari Beds, basalt/Cave sandstone aquifer and Middle Ecca aquifers are given following core drilling programmes. ERTS photography was used to assist in obtaining a figure of 56 x 10 m of extractable water present in storage in the "sand rivers" of eastern Botswana. Detailed aquifer tests on a variety of aquifers are described and show that the secondary aquifers generally present often behave in a similar fashion to primary aquifer. Approximately 5 000 boreholes are presumed to be present in Botswana. It is estimated that 17% of the successful boreholes have yields in excess of 150 1/min. The siting of boreholes using geological/geophysical aids has resulted in an increase in the success rate of nearly 25%. New geophysical techniques for the location of ground water have been investigated and ground geophysical methods used include electrical resistivity, inductive and conductive electromagnetic, Afmag, self-potential and seismic reflection and refraction methods. The well-tried resistivity method remains the most successful technique but self-potential, Afmag and seismic methods have given encouraging results. Extremely detailed studies using environmental isotopes are described. These have enabled quantitative estimates of ground-water storage and turnover times to be made; have given round-water flow rates; have outlined areas of recharge; have enabled permeabilities to be calculated; have enabled a clearer picture of recharge mechanisms through the unsaturated zone to be built-up; and have provided important evidence of areas in which recent recharge has contributed to ground-water supplies. The studies have shown that measurable amounts of tritium are present over far wider areas than originally anticipated and thus more recharge is taking place than thought earlier from laboratory tests and hydrogeological considerations. In Lobatse a water balance model is proposed and calculations based on this model indicate that some leakage, hitherto unsuspected, between several of the ground-water basins, take place. The carbon-14 method has, in addition, helped outline areas of recharge (Central Basin, Lobatse) which tritium had failed to do and has shown by using combined 3H and l4C data that mixing of young and old waters takes place. In the Kalahari, radiocarbon has been used to calculate ground-water flow rates, permeability and transmissivity. The oldest ground water in Botswana has an age of 33 700 years. Isotopic studies in the unsaturated zone have shown that water moves given rates downward at a rate of between 31 and 41 cm per year. Studies of water levels in boreholes have shown that nearly all boreholes show responses which can be directly correlated with seasonal recharge and hence the nature and frequency of recharge can be estimated. In addition, storage capacity and safe yield have been estimated using long term water level changes and knowing the amount abstracted from the basin. The rapid responses shown in some boreholes indicates surprisingly rapid recharge. Two boreholes in Botswana showed effects of the Tulbagh earthquake on 29th September 1969. The disturbance of semi-diurnal fluctuations in boreholes could possibly be used as an early warning device to predict catastrophic earthquakes. A prelimlinary annual safe yield for ground-water supplies in Botswana is estimated to be 4 x 10 9 m3 per annum. Tree roots have been found in boreholes at depths greater than 68m. This emphasises the role vegetation can have in causing transpirational losses from ground-water supplies. Irrigation from boreholes is unlikely to be profitable unless exceptionally large supplies are obtained or water be present at very shallow depth. Underutilised boreholes, e.g. boreholes drilled specifically for cattle ranching, could also be profitably used for irrigation. Details of ground-water chemistry and examples of fresh water overlying saline, saline water overlying fresh, chemical stratification with depth and changes in quality with time are given. The distribution of fluoride rich waters in Botswana is also given. This thesis has therefore attempted to outline the current status of hydrogeological research in Botswana and it is hoped that this will lay the foundation for later, more detailed and quantitative, studies. These will become even more vital than at present, as it is estimated that all readily available surface water resources in eastern Botswana will be fully utilised by the late 1980's and the country will rely even more heavily on ground water than at present. / Thesis (Ph.D.)-University of Natal, 1974.

Thesis (Ph. D.)--Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 1973. / Includes bibliographical references (p. 156-164).

A stratigraphic and structural study of the Archaean Pongola Sequence on the southeastern Kaapvaal Craton centred on the area around the Klipwal Gold Mine is described. The lower predominantly volcanic Nsuze Group is overlain with a gradational transition by the upper clastic Mozaan Group in which six formations are recognized. The Sinqeni, Ntombe, Thalu, Hlashana, Odwaleni and the Kulphiso Formations. The Sinqeni and Hlashana Formations are predominantly arenaceous while the Ntombe and Kulphiso Formations are mainly argillaceous. The Odwaleni Formation contains a diamictite which is interpreted as a tillite, and is therefore the oldest glacial rock on record. The stratigraphic position of the Kulphiso Formation is problematic. The Mozaan Group was deposited in a deepening epeiric sea which was invaded periodically by storm generated deposits. Dolerite and ultramafic dykes and sills of various ages are represented. Three phases of deformation are recognized in the Klipwal area. Early compression from the south-southeast initiated a major zone of bedding-parallel shear, the Izermijn shear zone, along the Nsuze-Mozaan contact and an oblique ramp, the Klipwal shear zone, at a higher stratigraphic level. An extensional phase caused reactivation of the Klipwal shear zone and the development of a major low-angle normal fault, the Gu'nsteling fault, above the Sinqeni Formation. The main phase of deformation, related to northeast-southwest compression is the most complex and most widely developed. Early northwest-trending subhorizontal upright folds were disrupted by contemporaneous north-striking dextral or dextral reverse shearing and northwest-striking sinistral or sinistral normal shearing. The obtuse relationship of these shear zones to the compression direction is probably the result of reactivation of basement structures with similar orientations. Northwest-trending folding continued during and after the shearing. The structural styles and orientations observed in the Klipwal area are recognized regionally in the main Pongola basin, highlighting the need for further detailed studies before basin-wide correlations are made. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

The Mesoproterozoic Ritscherflya Supergroup forms an extensive volcano-sedimentary cover succession on the Archaean Grunehogna Province of western Dromring Maud Land, Antarctica. The oldest:, predominantly sedimentary deposits of this cover succession are exposed across the Borgmassivet and southern Ahlmannryggen mountain ranges, and are collectively assigned to the Ahlmannryggen Group. A revised lithostratigraphy places exposures from these two regions in separate subdivisions, with three formations being recognised in the Ahlmannryggen (Pyramiden, Schumacherfjellet and Grunehogna Formations) and four formations being defined for the Borgmassivet (Veten, Framryggen, HogfOlma and Brapiggen Formations). Deposition of these successions occurred in a combination of fluvial braid-plain and braid-delta plain environments, with exposures in the Ahlmannryggen and Borgmassivet regions representing contemporaneous sedimentation in different portions of the same basin, under similar conditions. The development of the Ahlmannryggen Group basin is attributed to flexing associated with continental collision during the assembly of Rodinia. Collision and accretion of a continental island arc terrain (the Maudheim Province) along the southern margin of the Grunehogna Province is considered responsible for flexural snbsidence and the development of a peripheral foreland basin. The Ahlmannryggen Group represents 'molasse' stage infilling of this basin, with sedimentation being dominated by a combination of transverse and longitudinal drainage systems entering a depo-centre located to the east/southeast of the presently exposed succession. SAMANTIIA PERRlTT Detritus entering the basin was sourced either directly or indirectly from at least seven different terrains, aged ca. 1135Ma, ca. 1335Ma, ca. 1600-1700Ma, ca. 2000-2100, ca. 2645Ma, ca. 2400-2900Ma and ca 2900-3300Ma, according to UlPb detrital zircon SHRIMP analysis. The source terrains included the Maudheim Province, basement granites of the Grunehogna Province, an older sedimentary terrain dominated by a banded ironstone association, at least two further magmatic provinces and two metamorphic terrains. Of these source terrains, only the Maudheim Province and Grunehogna Province basement granites are presently exposed in western Dromring Maud Land The subsequent development of large-scale buckle folds and extensive brittle deformation within the Grunehogna Province cover rocks is attributed to the formation of a regionally extensive sinistral strike-slip system during NNW-SSE Pan-African compression, and can be correlated to structures exposed in the Maudheim Province and northern Mozambique. It is proposed that this strike-slip system developed in response to escape tectonics operating during a late stage of Gondwana amalgamation, as a result of the Ross Orogeny, and the suturing of East and West Antarctica / Thesis (Ph.D.)-University of Natal, Durban, 2001.

The oldest rocks of western H.U. Sverdrupfjella, the Jutulrora Formation, consist of interlayered mafic to felsic ortho- and paragneisses thought to represent calc-alkaline volcanic and clastic sedimentary rocks. These rocks are structurally overlain by the largely paragneissic, carbonate- dominated Fuglefjellet Formation which may represent a miogeosynclinal shelf facies. This sequence is structurally overlain by the dominantly para-gneissic Sveabreen Formation which may comprise a eugeosynclinal facies. Three granitic bodies, the Roerkulten, Jutulrora and Brekkerista Granites intrude the Jutulrora Formation. The trace element chemistry of these granites suggest that accessory minerals played significant roles during their generation and crystallization. Various mafic intrusions, now discordant amphibolites, and a phase of diorite veining are present. The Dalmatian Granite was emplaced syntectonically with the 470Ma Pan-African (or Ross) orogeny during D3. This granite was generated by crustal anatexis at >5kb. Jurassic age intrusions include alkaline complexes at Straumsvola and Tvora and numerous dolerite dykes, some of which postdate the alkali intrusions. Five episodes of deformation are recognised. The first two resulted in folds (F1 and F2) which are co-planar and coaxial resulting in type 3 interference structures. Low angle thrust faulting occurred during D2. Fold vergence and associated lineations suggest tectonic transport from the southeast during D1 and D2, D3 involved folding and reverse faulting. The orientations of the fault and axial planes of these structures suggest transport from the west and north-west. D4 involved open dome and basin folding. D6 involved normal faulting and jointing, adjacent and parallel to the Jutulstraumen Glacier in the west. The joints affect the Tvora Alkaline Complex. Three phases of metamorphism, related to the deformation, are recognised. The dominant mineral assemblages are typical of medium to high grade metamorphism and define S1 and S2 planar fabrics. Discordant mafic intrusions provide evidence of a long history of metamorphism. M3 mineral development, commonly represented by biotite, is oriented axial planar to D3 folds. Comparison of the geology of the area with that of southern Mozambique reveals many similarities. These support reconstructions based on geophysical data which juxtapose Dronning Maud Land and southern Africa prior to the break up of Gondwanaland. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1992.

The ~3.0 Ga Pongola Sequence, comprising a lower dominantly volcanic Nsuze Group and an upper largely sedimentary Mozaan Group, crops out in the Mahlangatsha and Kubuta areas of southern Swaziland. The Nsuze Group consists of basaltic, andesitic, dacitic and rhyolitic rocks with intercalations of ferruginous shale and pyrophyllitic schists. The Mozaan Group comprises quartzites, ferruginous shales, basalts and minor amounts of andalusite and sericitic schists. In the study area in southern Swaziland the Pongola Sequence is represented by a northerly striking lens of metavolcanic basaltic rocks extending southwards to the Ngwavuma River valley. These lavas comprise basalts, basaltic andesites and very minor rhyolites that are amygdaloidal and vesicular in places. Hunter (1952) tentatively correlated these metabasaltic rocks with the Nsuze Group but the geochemistry indicates that an upper Mozaan correlation is more likely. In the study area four stages of deformation have been deduced: a cleavage development (D1); low angle thrusting and bedding-parallel thrust faulting (D2); normal/oblique slip faulting (D3) and fracturing/jointing (D4). There has been duplication of strata by thrusting and normal faulting. Absence of marker beds prevents the determination of the degree of duplication. It is clear from the geochemical analysis that there are two broad groups of data from the suite, one from the Sigwe Hills in the north and the other from south of the Ngwavuma River. The samples from south of the Ngwavuma River are enriched in TiO2, AI2O3, CaO, Cr, Zr and Nb compared to the samples from Sigwe Hills. These volcanic rocks are tholeiitic in nature and indicate a within plate continental setting. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 1993.

Bathymetry forms the basis for studies in marine geology, biology and oceanography and is essential for the Extended Continental Shelf Claim (ECSC), a legal framework established by the United Nations (UN) to encourage a nation’s governance and management of its marine resources. This research provides the first digital, integrated, Geographical Information System (GIS) based bathymetric dataset for KwaZulu-Natal that combines near-shore and deep-water datasets for use in marine sciences. A total of 32 datasets acquired using a range of techniques and instruments between 1911 and 2006 were considered. Twenty nine of these were near-shore datasets with data densities varying from 6 to 57 406 points per km2. Of these, 15 were acquired by the Council for Geoscience (CGS), 9 by the South African Navy and 5 by the African Coelacanth Ecosystem Programme (ACEP). Two of the remaining 3 deep-water datasets were grids acquired digitally for this work, while the third was a digitised contour dataset. The 2003 General Bathymetric Chart of the Oceans (GEBCO) grid is based on digitised point and contour data with a point every 1 852 m, while the 1997 Smith and Sandwell grid is based on predicted satellite altimetry data with a point every 3 704. The third deep-water dataset was digitised from a northern Natal Valley bathymetric contour map developed in 1978 and has data densities varying from 0.02 to 1 point per km2. Datasets were prioritised in the following descending order of quality defined by the available metadata: multi-beam echo-sounder-derived datasets, followed by single-beam echo-sounder-derived datasets and lastly lead line datasets. The digitised northern Natal Valley bathymetric contour dataset after Dingle et al. (1978) was considered authoritative for the deep-water areas, while the 2-minute interval Smith and Sandwell satellite derived bathymetry dataset was integrated south of 31o S where no other dataset coverage existed. Availability of good metadata describing bathymetric dataset positioning and depth measuring instruments were essential. Where good metadata did exist, interrogation, integration and quality control were straightforward. However, where the year of acquisition and depth measuring instrument type were the only available metadata, information about positioning and depth measuring instruments were inferred. The digitised northern Natal Valley bathymetric contour dataset offered the best deep-water coverage and was derived from heterogeneous point datasets about which no metadata was available. Metadata for the Smith and Sandwell satellite derived bathymetric dataset suggested limited ship track data control for the study area, while it was known to contain noise caused by an unquantified, rough sea state. The integration process was successful but noticeable artefacts were recognised. Concentric contour artefacts were present where the digitised northern Natal Valley bathymetric contour dataset and the South African Navy Admiralty Fair Chart 34 dataset were integrated. Regional conjoined arc-like contour artefacts north of 31o S as well as bumpy seafloor textures south of 31o S in the deep water areas were also found. In addition, artefacts were discovered in one of the multi-beam datasets, normally associated with good high-resolution data coverage. Intuitive, user-friendly, Geographical Information System (GIS) software and mapping software were used to aid visual interrogation of the final contour dataset and the contour editing capabilities in ESRI ® ArcGIS ® were used to edit concentric contour and conjoined arc-like contour artefacts north of 31o S. GIS software was further used as a visual filter to remove the regional bumpy seafloor texture south of 31o S, caused by noise in the satellite altimetry dataset. An edited point dataset component south of 31o S was re-interpolated and the resultant grid re-mosaiced with the original final grid north of 31o S, yielding an improved final contour dataset. The 1:3 000 000 scale final contour dataset resolved regional features such as the Thukela Cone, the Thukela and 29o 25’ Canyons along with a broad un-named valley, termed here as the Maputaland Valley, which drains the Maputaland Canyons. Near-shore areas of the continental shelf were also resolved at higher scales of up to 1:45 000. Obvious data gaps emerged with five areas prioritised for the acquisition of new digital data as part of a systematic mapping programme to improve the dataset. Powerful, cost-effective computer hardware and cost-effective, intuitive, user-friendly computer software driven by ongoing technological advances made this work possible. These technology advances continue to improve bathymetric data acquisition, positioning and processing methods as well as improving data interpolation and map development. The usefulness of this digital, integrated, marine GIS contour dataset has been demonstrated by the interest of KwaZulu-Natal based organisations such as the University of KwaZulu-Natal (UKZN), the Oceanographic Research Institute (ORI), Ezemvelo KwaZulu-Natal Wildlife (EKZNW) and Umgeni Water along with the Cape Town based Marine and Coastal Management (MCM) and the Pretoria based Council for Scientific and Industrial Research (CSIR). Establishing this dataset as a base map for a KwaZulu-Natal 3D marine cadastre to add other GIS data must be encouraged to improve collaboration, promote research and improve ocean governance in KwaZulu-Natal, after which this type of 3D marine cadastre should be extended to include the whole of South Africa. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

Thesis (Ph.D.)-University of Durban-Westville, 1999.

The geological formations of Maputo City, which are mainly unconsolidated materials with soil like properties, are described in terms of their engineering geological and geotechnical characteristics with relevance to their distribution patterns and spatial trends. Problematic conditions such as collapse potential characteristics, loose aeolian sand dune deposits and loose sand plains characterize many of the materials. The geological characteristics combined with anthropogenic interference such as intensive urbanization with inappropriate land use, construction in sensitive areas like steep sandy slopes has led to many problems including slope stability. Foundation problems with building settlement and gully erosion also occur. The aim of this research was to study the engineering geological characteristics and the geotechnical properties of the geological formations of Maputo City and various related problems. Special relevance has been given to the understanding of three specific problems: building damage, gully erosion and slope instability. The geological formations are predominantly sandy (coarse to very fine sand) with very low clay content, are non-plastic and are classified as from the group SP-SM which are poorlygraded sand with silt. The majority of the materials are loose and normally consolidated with a high level of residual strength. Assessment of collapse settlement through double consolidation technique indicated soil compressibility and significant sensibility to collapse upon wetting. Truly collapsible soils that show full collapse of the soil structure were identified in 33% of the tested materials where the highest collapse behaviour reached values above 5%, predicted to cause moderate trouble in foundation design. Some of the bonded materials are bonded (evident in 67% of samples tested). Bonding was confirmed by comparing the compressibility of the undisturbed and remoulded samples. The remoulded samples showed a significantly higher compression than that of the bonded materials as part of the stress applied is carried by the bonds themselves, as the bonded material is stiffer than the same without bonds. The curves of the remoulded samples were used to establish the limit between the stable and meta-stable states of the material. A qualitative evaluation of the erosion susceptibility was investigated by physical tests such as the crumb test, shear strength and chemical indicators while a quantitative evaluation of the erodibility characteristics was obtained using a flume test. Some correlations were found between the results of various methods. Almost all samples that were found to be dispersive with ESP were also dispersive with TDS vs. %Na and SAR. Results of the flume erodibility test have very little correlation with the chemical properties related to dispersion revealing that the erosion susceptibility and gullying in Maputo City have more relation to the physical processes than to the dispersion related chemical properties of the soils. The positive identification of dispersive and erodible soils can only be carried out using a combination of various techniques. Therefore, a new rating system for erosion susceptibility of sandy soils combining the physical and chemical factors of dispersion is proposed including the flume test, crumb test, TDS/%Na, SAR and ESP. The proposed rating system was applied to the tested soils of Maputo City. Fifteen samples (83% of the rated samples) were classified with intermediate susceptibility to erosion while 3 samples (17%) were classified as having a low susceptibility to erosion. The highest rating scores were obtained by the same samples that showed dispersive behaviour with SAR, ESP and TDS/%Na. This group of samples was of intermediate erodibility in the flume test. The slope instability mechanisms observed in Maputo City are predominantly rotational failures with a mass of soil sliding along a curved surface of rupture followed by sand flow at the toe as failure occurs in the presence of excess water. Four groups of factors account for the slope instability problems in Maputo City: geomorphological causes, physical and meteorological causes, geological and geotechnical properties of soils, and anthropogenic causes. The mechanism of failure is mostly due to the loss of matric suction of soils in the presence of rainwater and possibly from destruction of bonding agents. Factors of safety values indicate that the slopes are generally unstable with the control being the slope angle. The slopes in the Polana-Caniço and Ferroviário Quarters show high factor of safety values but is the area most affected by slope instability. Slope failure in these areas is intrinsically caused by anthropogenic factors related to inappropriate land use planning. The gully sidewalls are unstable as the slope created is very steep. The slope at Friedrich Engels Avenue causes most concern due not only to the slope height and angle but also to the size and number of buildings constructed at the crest, mainly high rise buildings along the Julius Nyerere Avenue, the integrity of which could be threatened by a landslide event (this slope has recently been affected by active landslides). / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.

Rutile, although not a major component of detrital heavy mineral deposits, is a valuable source of titanium oxide. Theoretically rutile is pure titanium dioxide (TiO2) and should form white or colourless tetragonal crystals with a density of 4.25gm/ml. However, natural rutile although tetragonal, displays a variety of colours ranging from red through brown to black, yellow or blue, variable density between 4.23 to 5.50g/ml as well as a range in the magnetic susceptibility and electrical conductivity. In addition to these variations exhibited by natural rutile, samples from detrital heavy mineral deposits normally contain, in addition to homogenous grains, composite grains, in which rutile is intergrown with one or more mineral species, commonly quartz, feldspar and ilmenite. The Sibaya Formation, like most detrital heavy mineral deposits, has a polymictic source, and as such contains rutile grains formed in many different chemical environments. Homogenous rutile grains display a chemical variation with a preference for the select few elements, which are compatible with the rutile cyrstallographic structure. The ions that substitute for titanium (Ti4+) in the crystal lattice are a reflection of chemical environment in which the crystal formed. The size and charge of the Ti4 + ion greatly restricts the species that may enter the rutile crystal lattice, with Sb3 +, V3 +, Fe3 +, Cr3 +, Sn4 +, M04+, W4+, Mn4+, 8i5+, Nb5+, Ta5 +, Sb5 +, V5 +, being theoretically compatible with the size and charge of the Ti4+ ion. Electron microprobe analysis of detrital rutile grains from the Sibaya Formation, KwaZulu-Natal show that elements, Nb5 +, Ta5+, A13+, Zr4+, Si4+, Fe3+, Cr3 +, and V5 +, commonly substitute for the Ti4 + ion. However, Sb3+, Sn4+, M04+, W4 + and 8i5 + were not present at detectable levels implying that the provenance area is not enriched in these elements. Although the high Fe3+ values were expected in the rutile grains, as Fe3 + is common in many rocks, the high Si4+ values encountered were not expected, as Si4 + is not normally compatible with Ti4 + ion, as noted by their distinct separation in rutilated quartz. The anomalous Si4 + content of certain grains suggests that within the provenance area rutile bearing rocks formed under unusual conditions, such as high pressure, temperature and silicon activity where the high charge density of the Si4 + ion would favour the inclusion of Si4 + into the rutile lattice. The chemical variation of the rutile grains causes significant variation in the magnetic susceptibility and electrical conductivity, and thus has marked effects on mineral processing, which relies heavily on magnetic and electrostatic separation techniques. The data presented indicates that individual homogenous rutile grains displays significant range of chemical composition, commonly containing other oxides from a fraction of a weight percent to well over 10wt%. Data plots of TiO2, FeO and 'other' oxides (Nb2O5, Ta2O5, A12O3, ZrO2, SiO2, Cr2O3 and V2O3), showed that many of the more magnetic rutile grains appeared to be FeO enriched and contained a higher proportion of 'other' oxides. However, some grains that just had higher proportions of 'other' oxides and a lower FeO content were also magnetic. Thus magnetic susceptibility although strongly influenced by the presence of FeO, can also be enhanced by the substitutions of other oxides. The vast majority of rutile grains from the electrostatic fractions were relatively TiO2 pure, and contained low concentrations of 'other' oxides. However, some grains did have slightly enhanced SiO2 and V2O3 concentrations, which appear to enhance the conductivity of the grains. Four main colour groups were differentiated from the population of rutile grains from the Sibaya Formation, these being, reddish brown, black, blue and yellow. No single oxide seemed solely responsible for the colour of rutile grains. However, the red rutile grains had a slightly but significantly higher Cr2O3 and Nb2O5 content, whereas black rutile grains appeared to be V2O3 and Nb2O5 enriched. The blue colour of rutile grains appears to be influenced by a combination of SiO2, Al2O3 and Nb2O5 substitutions. The yellow rutile grains had slightly enhanced FeO and Nb2O5 concentrations. Although these differences are very small, trace quantities of certain elements and different combinations of elements can have a strong effect on colour. Apart from Fe3+, no single element; appears to be solely responsible for variations noted in the physical characteristics (magnetic susceptibility, electrostatic conductivity and colour) of homogenous rutile grains from the Sibaya Formation. However a combination of substituting elements appears to influence magnetic susceptibility and electrical conductivity. An enhanced Fe3+ content normally increases the magnetic susceptibility although combinations of other elements may have the same effect on Fe3+ poor grains. In general terms, the purer the rutile grain, the more likely it is, to be non-magnetic and conductive. Substitutions of 'other' oxides appear to decrease the conductivity of rutile grains. The relationship between grain colour and chemistry is also not very clear, verifying the widely held view that grain colour is often the result of more than just mineral chemistry. / Thesis (M.Sc.)-University of Durban-Westville, 2002.