Orientador: Jaime Amaya Farfan / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T00:38:42Z (GMT). No. of bitstreams: 1 Quintaes_KesiaDiego_D.pdf: 770146 bytes, checksum: a1f6c3db11ecbf42e1a69159f9578501 (MD5) Previous issue date: 2004 / Resumo: A pedra-sabão, a cerâmica, o vidro, o ferro, o alumínio e o aço inoxidável, estão entre os diversos materiais empregados na confecção de utensílios culinários. É sabido que durante a elaboração culinária, interações entre os alimentos e os utensílios ocorrem: algumas benéficas, outras inócuas, enquanto que outras podem ser prejudiciais à saúde do comensal. O presente estudo visou avaliar as implicações nutricionais que os utensílios nacionais de ferro fundido, de pedrasabão (esteatito) e de aço inoxidável (inox), podem ter. Os utensílios foram testados com simulantes de alimentos (ácidos acético e láctico) e com preparações culinárias (arroz e molho de tomate) a fim de determinar qualitativa e quantitativamente os elementos migrantes. Os materiais apresentaram perfis de migração distintos e susceptíveis à variação, conforme o simulante (ácido acético ou lático) e a aplicação do utensílio (cocção ou estocagem). As panelas de inox e de ferro não apresentaram implicações toxicológicas, sendo que estas últimas liberaram quantidade expressiva de Fe. Já as panelas de pedra-sabão liberaram teores consideráveis de Ca, Mg, Fe e Mn durante a cocção e, Ni em quantidade indesejável foi liberado na condição de estocagem por 24horas de ácido acético. No caso dos alimentos, foi observado que o molho de tomate preparado em panelas de pedra-sabão apresentou maiores teores de Ca e Mn em relação ao arroz. As panelas de ferro liberam quantidades expressivas de Fe e Mn durante a cocção de molho de tomate quanto de arroz. A estabilidade oxidativa do óleo de soja refinado foi avaliada em função do material da panela (inox, ferro, pedrasabão, vidro e alumínio) e a liberação metálica do utensílio. O uso de panelas de pedra-sabão, inox e de ferro resultou em óleo com menor estabilidade oxidativa, sendo que as duas primeiras liberaram maior teor de ferro para o óleo em relação à de ferro. O óleo de soja refinado mostrou maior capacidade de reciclagem ao aquecimento descontínuo quando a panela era de vidro ou alumínio. Visando determinar a biodisponibilidade do ferro derivado das panelas de ferro e de pedrasabão, foi realizado ensaio envolvendo população susceptível à anemia: mulheres em idade fértil e indivíduos vegetarianos (Comitê de Ética em Pesquisa, UNICAMP, parecer Nº 317/2001). Os participantes tiveram alíquotas de 10mL de sangue coletadas para a realização dos exames: transferrina, ferritina, ferro sérico e hemoglobina. A seguir foi iniciado o uso regular das panelas de ferro e pedrasabão no preparo das refeições, as primeiras por indivíduos vegetarianos de ambos os gêneros e, as segundas por mulheres em idade fértil. Novas amostras de sangue foram coletadas, visando a determinação dos mesmos indicadores hematológicos, após 10 semanas para os usuários das panelas de pedra-sabão e 12 semanas para os das de ferro. Os resultados da primeira e segunda coletas foram comparados a fim de estimar a biodisponibilidade do ferro derivado dos utensílios. Foi verificada a melhoria do estado nutricional relativo ao ferro nos voluntários quando os utensílios de alumínio foram trocados pelos de pedrasabão. Entretanto, não foi possível apontar com certeza a verdadeira causa desta melhora, uma vez que a extensão da migração de Fe para alimentos preparados nestes utensílios é inexpressiva. Já entre os usuários das panelas de ferro, o índice de anemia ferropriva passou de 38 para 20% ao final do estudo, mostrando que o ferro derivado das panelas deste material foi parcialmente utilizado pelo organismo. O estado nutricional relativo ao ferro de indivíduos sob regime ovolactovegetariano é passível de ser melhorado mediante preparo das refeições em panelas de ferro fundido / Abstract: Soapstone, clays, glass, iron, aluminum, stainless steel, are among the different materials used to make cookware. It is known that during food preparation interactions between the food and cookwares do occur, some of them being positive, some null, while others could be harmful for our health. This study evaluated the nutritional implications that result from using utensils made out of steel, soapstone and stainless steel materials. The utensils were tested with food simulants (acetic acid and lactic) and with some food preparations (rice and tomato sauce) in order to determine the quantity and quality of the migrating elements. All materials presented different migration profiles and were susceptible to variations according to the simulant and the utensil¿s application (cooking or storage). The stainless steel and iron cookware did not exhibit toxic implications but the later released substantial quantities of iron. On the other hand, the soapstone cookware released considerable amounts of Ca, Mg, Fe and Mn during cooking. Soapstone utensils also released undesirable quantities of Ni under storage for 24 hours with acetic acid. During food preparation, soapstone pans releases more Ca and Mn to tomato sauce than to rice. Iron cookware released Fe and Mn to tomato sauce and rice. The oxidative stability of refined soybean oil was evaluated after successive heating cycles in pans made of stainless steel, iron, glass and aluminum, with respect to the metal migration in each material. The use of the soapstone, stainless steel and iron resulted in lower oxidation stability. The soapstone and the stainless steel pans released more iron to the oil than iron cookware. The soybean oil showed greater stability for being re-heated discontinued when the material of the pan was either glass or aluminum. In order to determine the bioavaliability of the iron migrated from the soapstone and iron cookware, a study with two groups of individuals susceptible to iron deficiency was conduced. The study was ethically previously approved by the UNICAMP Ethic and Research Committee (317/2001). The participants, pre-menopausal women and vegetarians of both genders, had 10mL of blood collected for determination of the following indicators: transferrin, ferritin, serum iron and hemoglobin. After the males and females vegetarians started to use for 12 weeks the iron cookware and the pre-menopausal women started to use for 10 weeks the soapstone cookware on a regular basis for cooking their meals. New blood samples were collected and the same hematological tests re-evaluated. The results between the first and second blood tests were compared to verify the bioavalability of iron from both types of cookware materials. Changing the cookware from aluminum to soapstone improved the nutritional iron status significantly. However, it was not possible to unequivocally determine whether the status upgrading was due to the iron migration for the levels of Fe migration from soapstone pans was found to be almost insignificant. Among users of the iron cookware, the anemia index was reduced from 38 to 20% at the end of the study, showing that the iron released from iron cookware was at least partially utilized by the human body. The nutritional status of iron in individuals under vegetarian diet could be improved by meal prepare in iron cookware / Doutorado / Doutor em Alimentos e Nutrição

En la minería actual, la mayor parte de los proyectos mineros contempla una etapa de exploración y evaluación de recursos. Se comienza con una toma de muestras, como lo es una campaña de sondajes para poder interpretar las litologías y alteraciones presentes, definir las zonas minerales más relevantes y describir la distribución de leyes de elementos de interés, de tal forma de llegar a un modelo de evaluación del yacimiento. Para determinar el potencial económico de un yacimiento existen herramientas y técnicas geoestadísticas de evaluación y modelamiento de recursos tales como el kriging o la simulación condicional. La primera permite hacer una estimación insesgada y precisa de las leyes, obteniéndose un modelo suavizado que no representa la variabilidad. La segunda posibilita realizar un estudio de la incertidumbre de los valores involucrados en los atributos geológico-minero-metalúrgicos y tener análisis de riesgos a considerar para la toma de decisiones. En esta memoria, se aplican simulaciones geoestadísticas para cuantificar los recursos minerales de un yacimiento perteneciente a Antofagasta Minerals SA (AMSA), ubicado en la Región de Antofagasta, Chile, el cual ha sido interpretado, recientemente en diez dominios minerales y evaluado por kriging a través de información de sondajes. Utilizando un algoritmo de simulación para variables categóricas, específicamente el algoritmo secuencial de indicador, se construye once modelos alternativos de dominios minerales. Luego se utiliza un algoritmo de simulación de variables continuas (secuencial gaussiano) para obtener once modelos de bloques para leyes de cobre total y cobre soluble, cada uno asociado con un modelo particular de dominios minerales. Se realiza la validación comparando las realizaciones con los datos originales, el modelo de kriging y el modelo geológico interpretado. Finalmente se construyen curvas tonelaje-ley para cuantificar los recursos para distintas leyes de corte. Considerando una ley de corte de 0.2% en cobre soluble, se obtiene para los modelos de simulaciones que, en promedio, hay 53 millones de toneladas con ley media de cobre soluble de 0.86%, en contraste con los 50 millones de toneladas de ley media 0.73% entregadas por el método de kriging, lo que entrega una diferencia aproximada de 90 mil toneladas de cobre fino. Así, existen zonas en el yacimiento donde la diferencia entre el modelo de kriging y los modelos simulados son relevantes. Debido a esto, es recomendable nuevas campañas de sondajes enfocadas en estas áreas para obtener información de mejor calidad que permita reducir la incertidumbre. También sería interesante considerar la mineralización de ganga como una de las variables a simular, para así tener modelos predictivos del comportamiento de cada bloque en los futuros procesos metalúrgicos.

Abstract This thesis examines the Mid-Pliocene climatic extreme ca. three million years ago (Ma) which was the latest longtime warm period. It is an important topic because the climate back then was warmer compared with the present. The bipolar regions are studied because they represent the largest areas that control the global climate. This study is based on clay mineral research that may significantly improve our knowledge of the Mid-Pliocene climate when combined with other palaeoenvironmental data. The paleoclimatological objectives of this study were: 1) to investigate how clay minerals reflect the Mid-Pliocene Global Warmth event, 2) to study ice sheet development at high latitudes, especially in East-Antarctica, and the history of ice rafting and sea ice, especially in the Arctic Ocean. This thesis deals with the clay mineral distribution and compositional analysis of the Pliocene-aged marine sediment sequences provided by the Ocean Drilling Program (ODP). The first studied site, Site 1165, is located at the continental rise of Prydz Bay, East Antarctica, and the second studied site, Site 911, is located at the Yermak Plateau, north of Svalbard, in the Arctic Ocean. The Pliocene smectite clay minerals at Site 1165 were mainly derived from Antarctic continental sources and transported to the site primarly by bottom currents related to warm events during the last 5 Ma. The evidence obtained in this study shows that the East Antarctic ice sheet may have been a dynamic ice sheet during the past 5 Ma, especially during the Mid-Pliocene. The results from the Mid-Pliocene possibly suggest a general warming trend. Based on the composition of the heavy minerals and clay minerals, at Site 911, the Pliocene smectite clay minerals were mainly transported within sea ice by the Siberian branch of the Transpolar Drift. The results indicate a warming trend at approximately 3 Ma after which they indicate a shift back to glacial conditions. Based on this study, the Mid-Pliocene Global Warmth can be observed in both the Arctic and Antarctic regions.

[From introduction] Exploration geochemistry is an indirect method of detecting mineral deposits by measuring the abundance and distribution of ore elements and elements closely associated with ore in natural materials at or near the earth's surface. The method relies on the assumption that a mineral deposit is reflected by unusual element abundances or distribution patterns (geochemical halos), and that these indications of mineralization can be detected by geochemical surveys involving the collection and analysis of natural materials. The interpretation of geochemical surveys in mineral exploration involves: 1) The use of geological and statistical inference, based on a knowledge of the normal behaviour and distribution of indicator elements in the exploration area, to recognize apparent geochemical anomalies in field and analytical data and to predict the type of geochemical halo reflected by the anomalies. 11) The use of geological inference, based on a knowledge of the characteristics of geochemical halos and their relationship to mineral deposits, to predict the presence and probable location of an ore body. The interpretation process is, however, complicated by the absence of a simple universal formula that relates the abundance and distribution of elements in natural materials to the presence or absence of a mineral deposit. The interpretation of a geochemical survey must, thus, be based on an empirical approach which avaluates each survey as an individual problem. The objective of this dissertation is to illustrate the factors affecting the "nuts and bolts" approach to the interpretation of geochemical surveys in mineral exploration. The discussion is aimed at providing field geologists responsible -for the planning and execution of geochemical surveys with some basic guidelines for interpreting the surveys. I hope that the contents of this dissertation will help field geologists to "look in the last place first".

The coal industry of Mpumalanga Province is faced with the problem of developing cost effective ways of using large volumes of calcium and magnesium sulphate enriched waste waters. Use of the waste waters for agricultural production may contribute as a stabilising factor with regard to yields in this high potential agricultural area. The objectives of this study were to determine the effect of such waste waters on yield and to compare crop response to calcium and magnesium sulphate salinity at different nutrient levels. Two separate glasshouse experiments were conducted. Wheat (Triticum aestivum L. cv. SST 825) was grown in calcium and magnesium sulphate salinised nutrient solutions (Ca:Mg 2: 1) with differential levels of NO3, NH4, P and K. A soil pot experiment was subsequently conducted with maize (Zea mays, cv. PAN 6256), three gypsum and magnesium sulphate salinity levels and a 6 x 2 x 3 factorial combination of N, P and K. Calcium and magnesium sulphate salinity decreased the biomass production of both crops. This was mainly due to interactions of Mg with the uptake of essential nutrients in wheat and a Mg toxicity andlor Ca deficiency induced by high levels of Mg andlor SO4 in maize. The application of NO3, NH4, and K at rates different from the level considered beneficial for non-saline conditions improved wheat growth under sulphate saline conditions. Strongly inhibitory salinity levels controlled the maize yield of the highest salinity treatment regardless of the level of fertiliser application. A beneficial effect of higher NH4 supply was observed in both experiments. This can be ascribed to the antagonistic effect that NH4 exerted on Mg concentrations in plants (both experiments) and SO4 (soil pot experiment) and/or to a higher N-utilization efficiency where N was supplied as NH4 compared to NO3. Differential application levels of P had no effect on the yield of wheat. Phosphorus concentrations in maize were marginal to low, even at extremely high soil Bray I-P levels. This was probably caused by the precipitation of P as insoluble calcium phosphate complexes in the soil andlor between the free space of the cortex cells of plant roots. These results could also indicate that the Bray I extraction method does not give a true reflection of plant available P in sulphate saline soil. Further experimentation is needed to verify these results under field conditions and determine the optimal rate, method and timing of especially NH4 and PO4 fertilisers when irrigating crops with these calcium and magnesium sulphate enriched waste waters. / Dissertation (MSc (Plant Production and Soil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

M.Sc. / This study focuses on the Merensky Reef (MR) occurring within the Two Rivers Platinum mine property in the farm Dwarsriver 372 KT, on the Southern sector of the Eastern Limb of the Bushveld Complex. Five MR exploratory drill core intersections were obtained. Petrographic and mineral chemical characteristics of these drill core samples focused on the characterization of minerals like clinopyroxene, orthopyroxene, plagioclase, chromite and olivine. Data of the cryptic variation of orthopyroxene, plagioclase and chromite, from a 10 m interval (approximate thickness of the section studied); from footwall through the MR to the hangingwall lithologies at Dwarsriver are described in this study. Locally the vertical cryptic variation of these minerals is broadly consistent with regional trends of the RLS. The lateral variation (i.e. along strike) is less pronounced; however, locally these minerals appear to be chemically evolving moving to the south of the property. Footwall orthopyroxene compositions vary from a minimum of En66 and reach a maximum of En84. Those of the MR range from En71 to En85. Hangingwall orthopyroxene compositions range from En60 and reach a maximum of En80. Plagioclase compositions in the footwall units range from a minimum of An69 and reach a maximum of An85. Those of the MR range from a minimum of An35 to a maximum of An84. This wide range in plagioclase compositions is believed to be as a result of the increased presence of fluids within the MR interval. The hangingwall plagioclase compositions range from An64 to An84. By analogy of the Western Limb, where the lithologies of the Northwestern sector are believed to be proximal to the feeder of this limb; the local lateral variation in the present study suggests that the lithologies of either the Central or Western sectors are most probably proximal to the feeder for the Eastern Limb. PGM assemblages associated with and adjacent to the MR chromitite stringers were evaluated using an MLA. Data obtained from this technique is in broad agreement with regional studies of the MR. With the aid of wholerock PGE assays the MLA technique has proven to be a powerful tool in evaluating PGM assemblages relatively quickly, from a few carefully selected samples. The mineralogical associations of the PGM with the gangue and host minerals have shown three main associations. These are the associations of chromite, BMS and silicates with the PGM, of which the base metal sulfide (BMS) association is remarkable given that these have a relatively low modal abundance. The relatively high mineralogical association of the BMS with PGM has been explained by a model involving a base metal sulfide liquid which possibly scavenged chalcophile and siderophile elements. Chromite chemistry and modal analyses of MR secondary silicate phases, which peak adjacent to the chromitite stringers, suggests elevated fluid overprinting within and adjacent to the chromitite stringers. The upper chromitite stringers, however, have higher abundances of PGM phases that are believed to be secondary in origin relative to the basal chromitite stringers. Generally the PGM associated with the upper chromitite stringers are also bigger in size averaging 70 μm as opposed to 27 μm for those associated with the basal chromitite stringers. The increase in grain size of the PGM along with the higher modal abundance of secondary PGM phases associated with the upper stringers is believed to be as a result of fluids. These fluids although affecting both the upper and basal chromitite stringers, appear to have had a relatively higher influence on the upper chromitite stringers. The most common PGMs encountered in this study are isoferroplatinum, sperrylite, michenerite, maslovite, cooperite, laurite and braggite.

La desquamation en plaque est une forme de dégradation de la pierre monumentale fréquemment observée. Cette morphologie spécifique résulte de l’initiation et la propagation d’une fissure subparallèle à la surface, qui subit diverses sollicitations en conditions naturelles d’exposition. L’objectif de cette recherche est de mieux comprendre ces mécanismes d’altération et d’appréhender les paramètres déterminants dans l’initiation de la fissuration au sein des pierres mises en œuvre. Une approche en mécanique de la rupture a ainsi été proposée. L’influence des minéraux argileux, mis en cause dans ce phénomène, est étudiée et discutée. Trois pierres ont été sélectionnées, une molasse, un grès et une kersantite, présentant de nombreux exemples de desquamation lorsqu’elles sont exposées. Leur comportement hydromécanique est caractérisé en tenant compte de leur anisotropie naturelle. Les propriétés élastiques, la résistance à la traction et la ténacité sont mesurées après saturation, pour plusieurs humidités relatives en phase d’humidification et de séchage, et après plusieurs cycles de variations d’humidité relative. Un couplage de mesure des dilatations et des vitesses d’ondes acoustiques a permis un suivi précis de l’endommagement au fil des cycles. L’influence des minéraux argileux dans les processus d’altération a pu être vérifiée. Ces phases ont été identifiées comme des facteurs essentiels de la dégradation, car elles constituent des plans de fragilité favorisant l’endommagement et la fissuration du matériau, et ce d’autant plus qu’elles se dilatent lors des sollicitations naturelles. / Flaking is a deterioration pattern widely observed on monumental stone heritage. This pattern is due to the initiation and propagation of a crack subparallel to the surface of the stone exposed to natural weathering. This research aims to better understand the alteration mechanisms and to determine the parameters involved in such crack initiation within monumental stones. A fracture mechanics approach is proposed and the influence of clay minerals on this detachment alteration is discussed. The research is carried out on three stones, a molasse, a sandstone and a kersantite, showing scaling effect when submitted to natural conditions. Their hydromechanical behaviour is studied with respect to their natural anisotropy. Elastic properties, tensile strength and toughness are measured after saturation, at various RH values during humidification and drying, and after several cycles. Wave propagation combined with dilatation measurements is used to follow damage during the RH variations cycles. The influence of clay minerals on alteration processes is verified. These phases are critical factors of stone degradation as they are weakness planes leading to damage and cracking, especially generated by their swelling.

Magister Legum - LLM / This work deals with the potential impacts of contract review on foreign direct investments in mining resources. The research has cited Tanzania and the Democratic Republic of Congo as the case study because the two countries have experienced the problems generated from mining contracts review programmes. Indeed, there are some variations on the nature of the environments in which the reviews were made. While in the DRC the reviews were done amid civil wars (whose root cause was wealth emanating from mineral resources), in Tanzania the reviews were done without such pressure. However, the situation seems to have not been fully solved neither in Tanzania where the reviews were done under “peaceful” environment nor in the DRC where at least the past experience could have taught them a lesson. The mini thesis is divided into four chapters each covering a distinct topic for discussion. Chapter one serves as an introduction highlighting on the mission and vision of the research. It also spotlights the scope and limitation of the research. Chapter two is a discussion on the mining sector and foreign direct investments in Tanzania and the concept of mining contracts review based on the Bomani Commission report. In fact this chapter together with chapter three are the core of the research. In chapter two facts are laid bare of how the mining operations are done in Tanzania and how the management is undertaken. While in the subsequent chapter to wit chapter three, the same is observed but now targeting the Democratic Republic of Congo. The researcher has used these two chapters to demonstrate how inefficient the African governments are in running and maintaining the mineral resources by which they are endowed plentifully. Chapter four is also formal in the sense that the researcher provides his point of view on how matters could be rectified. It is a firm view of the researcher that if the governments take heed to what is recommended, there will much improvements in the mining sector which can be recorded in shorter span of production.

A review of the geotectonic settings of granitoids and various tin-tungsten provinces in Europe, Malaysia and southern Africa shows a close spatial and temporal association of mineralisation to S-type ilmenite series granitoids. Granitoids with these affinities are derived from crustal anatexis and are most commonly found in continental collision and different ensialic, intraplate orogenic settings, (e.g. SW England, Malaysia, Namibia) as well as in association with anorogenic magmatism (Nigeria, Brazil, South Africa). Tin-tungsten mineralisation is related to late- to post-tectonic granites, emplaced into areas of substantial tectonic thickening. Crustal anatexis leads to an observable calcalkaline chemical trend, with a source of gabbroic or amphibolite composition through anatexis to; mafic-intermediate enclaves, para-autochthonous anatectic granitoids (tonalite, granodiorite), to intermediate level quartz monzonite, granodiorite, biotite-granite, to late-tectonic highly fractionated muscovite-bearing granites, and high level porphyry intrusions. Mineralisation is spatially related to apical protrusions of the youngest most differentiated granite. Various mineralised environments are recognised, including endogranitic veins, primary disseminations, pegmatites and pipes, and exogranitic stockwork and fissure veins, and replacement bodies. A common factor to all these deposits is the inherent greisen environment, characterised by postmagmatic metasomatic alteration and mineral deposition. Common alteration mineral assemblages include albite, quartz, muscovite, tourmaline, and fluorite ∓ topaz. Ore mineral assemblages commonly display a paragenetic sequence of oxides (cassiterite, wolframite, scheelite), followed by sulphides (molybdenite, pyrite, pyrrhotite, chalcopyrite sphalerite, arsenopyrite/loëllingite, Pb-Bi(Ag) sulphosalts) and then lower temperature carbonates (calcite, siderite, ankerite). Analysis of Pan African orogenic provinces in southern Africa (Damara and Saldanian Provinces) shows there is good potential for applying integrated exploration techniques in search of endo-exogreisen Sn-W systems. Careful analysis and interpretation of granitoid geochemistry (K₂0, Na₂0, FeO/Fe₂0₃, F, B, Sn, W, Mo, Cu, Rb, Sr, Ti, Zr) should aid delineation of Sn-W and Mo-Cu metallogenic provinces in these regions. Magnetic susceptibility determinations should also aid distinction of S-type ilmenite series (less than 1 x lO⁻⁴emu/g ) from I-type magnetite series (more than 1 x lO⁻⁴emu/g ) granitoids

The Grahamstown clay deposits extend in a broad belt from 26°23 to 26°50 East longitude and from 33°15 to 33°22 South latitude along two distinct geomorphological features, the Grahamstown Peneplane (650 m) and the Coastal Plain (520m). The clay deposits traverse four different lithologies including the Bokkeveld Shale, Witteberg Shale, Dwyka Tillite and Ecca Shale. The two planes invariably have a covering of silcrete which is also present over most of the clay deposits except where erosion has taken place. X-ray fluorescence analysis shows that chemically there is a fairly wide variation between and witnin the deposits. The greatest variation is in the Si0₂/Al₂0₃ ratio which appears to be controlled by the parent lithology and to some extent by the amount of leaching. K²0 shows an increase in concentration with depth and therefore indicates the limits of hydrolysis and leaching and of the clay. X-ray diffraction study shows the Peneplane and Coastal Plain deposits to be quite distinct. The Peneplane deposits consist of kaolinite, illite and quartz and the Coastal Plain deposits of kaolinite, illite, quartz and pyrophyllite. The presence of pyrophyllite is not fully understood as there is no indication of major faulting, metamorphism or pyrophyllite in the parent rock. The pyrophyllite most probably represents a transformation product of kaolinite. The kaolinite from the various deposits shows a considerable variation in crystallinity in both the X-ray diffraction traces and electron photomicrographs. The most poorly crystalline kaolinites are from the Coastal Plain deposits and the difference in crystallinity is most probably due to differences in the degree of hydrolysis and the parent rock material in the case of the tillite. Genetically all of the deposits are residual types generated by hydrolysis and subsequent leaching of micas and feldspars. The principal elements leached are silicon, iron and potassium. The hydrolysis and leaching took place over a long period of time in the flat lying areas of the Peneplane and Coastal Plain. The deposits are exploited economically and the clay is used principally in the tile, pottery and whiteware industries with some usage in the paper, refractory and brickmaking industries. The price commanded by raw kaolin is not very high and as a result the clay industry in Grahamstown is not as viable economically as it could be.