Brazil is a significant producer of kaolin with almost 2.5 Mt in 2005 representing 10% of the world's total of 25.0 Mt. Brazil is now the second largest producer in the world, after the USA, having overtaken the United Kingdom in 2005. The kaolin resources are widespread throughout the country and are varied in their origin, physical and chemical properties and morphology. The kaolin industry in Brazil has shown a dramatic rise over the last 15 years with production of beneficiated kaolin increasing from 0.66 Mt in 1990 to 2.5 Mt in 2005. The reason for the growth is solely the development of large kaolin deposits in the Amazon Basin that account for 90% of Brazil's production. In 2005 there are just two companies involved in the production and sales of kaolin from the Amazon Basin, namely Imerys (RCC — Rio Capim Caulim) and Caemi (a subsidiary of CVRD — Companhia Vale do Rio Doce) with kaolin operations of CADAM (Jari River) and PPSA (Capim River operations).

A new method for determining the cation exchange capacity (CEC) of clays is proposed. The method is based on X-ray fluorescence analysis of natural and Ba-exchanged clays following the analytical procedure suggested by Franzini et al. (1975). This procedure, which utilizes powder pellets and is based on a full matrix correction method, is frequently applied in Earth Sciences laboratories for the routine analysis of minerals and rocks. For the analysis of Ba-exchanged clays, Franzini's procedure has been modified slightly to account for the contribution of Ba to matrix effects.

The new method, which furnishes both the CEC and the chemical compositions of the whole natural clay samples, has been tested on the eight ‘Source Clays’ of The Clay Minerals Society. The results compare well with data reported in the literature and confirm the accuracy and precision of the method and make it a valid alternative to techniques based on wet chemistry, execution of which is usually more time-consuming and which often requires greater analytical skill.

The dispersal of suspended matter in the Gulf of Cadiz (SW Spain) is related to its geographical position near the Strait of Gibraltar, and the continental margin, and to Atlantic and Mediterranean water flows and their interaction with the littoral tidal processes. The main direction for transport of suspended matter is towards the southeast, along the continental margin, from the mouths of the rivers Guadiana and Guadalquivir to the Mediterranean. This general transport pattern is perturbed by littoral processes such as those occurring in Cadiz Bay, where a portion of Atlantic suspended matter, driven by flood tide, comes into the inner bay and is deposited in the shallow waters of lagoons and salt marshes. Subsequently, because of the southeast wind and waves, these sediments are remobilized and transported to the west by the ebb tide, to deeper Atlantic waters. This dynamic interaction between Atlantic and littoral waters generates a different type of sediment layout, the origin of which is difficult to establish.

In order to understand the dispersal of the suspended matter and its effects on the inner continental shelf, the distribution of the main clay minerals has been determined by means of X-ray and Q-mode and R-mode factor analysis. The suspended matter dispersal paths were established through the distribution of main clay mineral associations and from the ratios amongst these minerals. The results allow us to determine the importance of the tidal flows in the suspended matter transport system of the Gulf of Cadiz. Therefore, a record was kept of which of the outgoing tidal flows from the inner parts of Cadiz Bay reached the continental shelf. The flows intercept the clear Atlantic waters giving rise to a complex sediment distribution and to the mix of clay minerals. The study has also allowed us to establish the sediment source areas and the extent of sediment transport and the paths they follow.

The relationships between different pools of K, i.e. exchangeable, HN03-extractable, mineral and total, were investigated as a function of clay mineralogy and soil development in soils of Kharkeh Research Station, Kurdestan Province, western Iran. Samples from different horizons often pedons were selected and analysed for clay mineralogy and K fractionation. X-ray diffraction patterns revealed that clay minerals in the soils studied were similar in type, while their abundances were different. The smectite content was significantly greater in Vertisols than in the other soils. The results of K fractionation showed that mineral K and HN03-extractable K (exchangeable and nonexchangeable, respectively) and the clay content of the soils containing lesser illite (10–30%) were significantly different from those with more illite (30–50%). Moreover, the regression slopes between water-soluble and NE4OAc-extractable K were lower in soils with more smectite due mainly to the presence of larger specific surface areas for K sorption in smectitic soils. Based on soil evolution and different forms of K, the soils studied were grouped in two major categories: (1) Vertisols and (2) Entisols, Inceptisols and Mollisols. There were greater contents of all forms of K in Vertisols than in the other soil orders. This was mainly related to the greater clay content and the dominance of smectite in the clay fraction of Vertisols.

Diagenesis in the Podhale and Orava Paleogene flysch basins and in the underlying Mesozoic structural units was studied by XRD measurement of the percent smectite in the mixedlayer illite-smectite from shales and K-Ar dating of the illite-smectite from bentonites, supported by XRD quantitative mineral analysis, grain density, and porosity measurements of the bulk shales. The diagenetic mineral reactions identified in the flysch shales include illitization of smectite (>60 to <5%S), dissolution of K-feldspar and kaolinite, crystallization of quartz, albite and chlorite. An unusually large amount of basin history information was obtained by combining the illite-smectite data from wells and from the present erosional surface of the basin.

The rocks underwent burial diagenesis at a stable geothermal gradient similar to the present-day value of 21±2°C/km. The maximum burial temperatures were reached very quickly (high sedimentation rate) close to the basin inversion time, at ∼17 Ma in the western part and 18 Ma in the eastern part.

The basin floor, which included the present-day Tatra Mts., was inclined towards the East. The thickness of the sedimentary filling of the basin ranged from 3.5–4.5 km in the western Tatra (removed entirely), to 5–6 km in the western Podhale (<3–4 km removed), to 6.5–7.5 km in the eastern Podhale (>4–5 km removed), and even more in the eastern Tatra and Spisská Magura close to the Ružbachy Fault. These data imply a major subsidence followed by uplift of the Podhale plus Tatra block along the Ružbachy Fault and the deposition of a thick sequence of Lower Miocene sediments over the entire area (latter removed by erosion).

The Mesozoic rocks of all the structural units underlying the flysch basin underwent advanced diagenesis (maximum palaeotemperatures of 160–270°C) during an Upper Cretaceous tectonic burial event at ∼80–90 Ma. The tectonic overload was removed before the Eocene transgression (49–42 Ma).

Raw clay materials manufactured for stoneware use are typically compounds of kaolins, silicas and feldspars. Two stoneware clay materials examined here were chosen because each is representative of the range of manufactured clay bodies. Samples were fired in an oxidizing atmosphere to a range of temperatures between ∼1000 and 1300°C. Sample dimensions, density, porosity and mechanical properties under compression were measured as a function of firing temperature. Thin sections, showing particles and their relationship to pore/void structures, were prepared, recorded under scanning electron microscopy (SEM), and analysed. The observed changes in microstructure can be related to previously described metamorphic and micro-eutectic reactions and a gradual sintering process. Indications of changes to apparent porosity are further amplified by measured changes of mechanical properties. The modulus of elasticity increases with reduction in porosity to a point at which porosity ceases to be the principal determining factor. The critical Griffith's crack length, calculated from fracture-strength measurement, exhibits a similar trend. The onset of these changes coincides with a significant increase in sealed porosity and with the microstructural metamorphosis as revealed by SEM.