The turbiditic facies of the Aquitanian-Oligocene of the Algeciras and Bolonia Units consist of lutitic-marly beds alternating with varied sandstones. Early diagenetic processes and the development of secondary porosity in sandstones were controlled largely by sedimentary facies. Mineral dissolution processes were important in rocks with high primary porosity (quartzose sandstones) and led to the development of allophane and kaolinite/dickite in later diagenetic stages. In rocks with high contents of biotitic matrix, chlorites and iron oxides were produced, together with the development of secondary porosity. In feldspathic sandstones, the early diagenetic processes produced chlorite, illite, illite-smectite mixed-layers and smaller amounts of kaolinite. In calcareous sandstones, the presence of an early cement prevented, to a certain extent, the dissolution of unstable fragments and restricted the development of clay minerals. The movement of fluids was not important during this early diagenetic stage in controlling the variety or abundance of mineral cements; the controlling factors were the different chemical conditions developed in the pore-solution of the various sandstone types. In spite of similar sandstone burial conditions, the different sandstone lithologies continued to determine the diagenetic processes, especially the degrees of compaction and dissolution. Certain burial processes are common to all levels: the development of reducing conditions is indicated by the development of Fe and Mn carbonates, Fe-dolomites and Fe-chlorites. A later alkaline diagenetic phase was responsible for the development of calcite, feldspar and illite. The circulation of fluids in these stages remained limited, although there was probably some movement from the lutitic-level fluids to the overlying sandstones.

Acid treatment causes natural “swelling chlorites” (like the similar synthetic material prepared by the authors) to change into montmorillonite. Some labile chlorites from Lorraine iron ore show a similar change on treatment with sodium hydrosulfite + sodium tartrate, or on electrodialysis, although certain of these show no swelling initially, The corresponding transformation with true chlorites is very difficult to achieve. Results have been checked by thermobalance (figs.), D.T.A., X-rays.

The characteristic feature of “swelling chlorites” is the easy passage back to the montmorillonites from which they were probably formed; not all such labile chlorites show swelling.

Thermal expansion measurements on unfired ceramic clays have provided a useful rapid method of estimating their quartz contents. Reversible thermal expansion measurements on the fired clay reveal changes in composition with firing, notably the development of cristobalite and of the glassy phase.

An informal overview is given of the development of the fundamental particle model, where, in a series of papers published from 1982-1987, researchers from the Macaulay Institute presented a radical model for the interpretation of the crystal structure, chemistry, and genesis of interstratified clays. The model reconciled electron microscopy and X-ray diffraction (XRD) data from a variety of sedimentary clay specimens, and proposed that these minerals were composed of nano-crystalline ‘fundamental particles’ whose adsorptive interfaces were responsible for the expanding smectite layers observed by XRD. The term ‘interparticle diffraction’ was used to describe this phenomenon. Experiments were reported which proved the model, by producing randomly interstratified illite-smectites from combinations of ordered illite-smectite and smectite clay dispersions. The model was extended to propose that fundamental particles were the primary units of crystallization, and that changes in the particle population were responsible for the commonly observed evolution in XRD character of these minerals with increasing depth of burial and temperature.

Un minéral interstratifié mica-vermiculite en paillettes de 1 à 4 mm2 est traité par des solutions concentrées de chlorure de sodium. Dans ces conditions une adsorption de sel dans les interfeuillets vermiculite se superpose à l'échange d'ions. L'adsorption de sel prédomine en solution concentrée et l'échange d'ions en solution moins concentrée. Des complexes salins sont ainsi obtenus. Ceux-ci possèdent la propriété de gonfler macroscopiquement dans l'eau avec désorption du sel. L'addition d'eau oxygénée aux solutions salines provoque également un gonflement. Cette propriété est utilisée pour la transformation du minéral en vermiculite. Le minéral et la vermiculite gonflés trouvent des applications intéressantes.

Sodium montmorillonite (MMT) was organically modified with hexadecyltrimethyl-ammonium ions and subsequently treated with dichlorosilanes and water, aimed at in situ silane condensation polymerization and modification of clay platelets by polysiloxane coatings. Dimethyldichlorosilane, methylphenyldichlorosilane, and diphenyldichlorosilane were used to produce three siloxane-modified organoclays. The structure and morphology of the clay materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric studies (TG) and scanning electron microscopy (SEM). XRD results showed that the silanes were effectively polymerized in the clay galleries, forming a nanocomposite of intercalated particles. A fraction of the siloxane formed is bonded to the clay surface by covalent siloxane bonds. Strong structural differences in both morphology and thermal stability of the materials may occur when changing methyl or phenyl groups in the siloxane structure. The formation mechanism of these intercalated nanocomposite particles is considered. Finally, these modified clays were incorporated in an olefin polymer and morphological analyses using transmission electron microscope (TEM) images were carried out.

Comparative porosity studies based on nitrogen sorption isotherms were carried out on six freeze-dried Na-montmorillonites (Moosburg, Camp Berteau, Marnia, Greek Yellow, Greek White, Wyoming bentonite), untreated and deferrated with dithionite/citrate. Mesopore analysis was carried out using the ‘parallel-plate model’; for supermicropores the ‘MP’ method was used. Most of the surface area was located in the supermicropores (width 7–15 Å). Higher total surface areas of the deferrated clays resulted from a much higher supermicroporous surface area, while the mesopore surface was similar or smaller. The lower the charge density of a subfraction of deferrated Wyoming (Na-)bentonite, the lower the vapour pressure at which the interlamellar sorption of ethanol occurred. The results predict an expansion on contact with the first traces of ethanol at 298 K for a Na-smectite with a charge density ξ = 0·11 e/(Si,Al)4O10 unit. Compared with ethanol, methylbromide showed a weaker interaction with Na-smectite. At p/p0 = 0·4 only 18 % of the interlamellar zones of low-charged Laponite were penetrated; one third of the supermicropores of this smectite were not accessible to CH3Br.

A thick deposit of flint clay in the Permian I llawarra Coal Measures of the southern part of the Sydney Basin, New South Wales, is described. The flint clays which have affinities with those of the Pennsylvanian of North America and with the kaolin coal tonsteins of the Westphalian, are associated with red-brown claystones that contain in addition to hematite, an abundance of a regular mixed layer clay mineral. Pyrophyllite generally forms a minor constituent only of the flint clays but in one part of the deposit it is more abundant than kaolinite. Although there are many puzzling aspects concerning the origin of the deposit, evidence suggests that the kaolinite and the pyrophyllite in the flint clays are detrital.

Rodrique et al. (1972) reported that kaolinite was formed at 200°C from gels with an A12O3/(A12O3 + SiO2) weight ratio ⩽0·315 and pH values ranging from 4·8 to 5·8. At this temperature and using a gel with an A12O3/(A12O3 + SiO2) weight ratio >0.315, boehmite and pseudoboehmite, were obtained at pH values of up to 5·8. The latter minerals were also observed in the products formed under similar conditions at 175°C.

Unlike the situation under acidic conditions, where gel composition is important, the gel/solution ratio becomes critical under alkaline conditions. When the gel/solution ratio is low, zeolites are produced from a gel with a weight ratio between 0·3 and 0·5 in the presence of NaOH at 130-170°C (De Kimpe, 1976). When the gel/solution ratio is high, kaolinite instead of zeolites is formed under similar conditions (De Kimpe, 1969, 1976). For an intermediate gel/solution ratio, smectite is produced from a gel with a weight ratio of 0.4 in the presence of NaOH at 175°C In the presence of KOH, however, kaolinite is the only crystalline product formed under similar pH and temperature conditions (De Kimpe et al., 1981).

En milieu organique, la formation de l'acide hippurique par contact d'un complexe montmorillonite-glycine avec de l'acide benzoīque est relativement facile. Dans ces conditions le peptide formé n'est pas hydrolysé. En milieu aqueux, par contre, l'activité catalytique de l'argile est insuffisante pour préparer l'acide hippurique à température ambiante. Une température minimale de 60°C est alors indispensable. Le rendement de la réaction qui est toujours faible dépend principalement de la nature du cation échangeable de l'argile. Les meilleurs résultats sont obtenus avec les montmorillonites contenant des éléments de transition tels que le cuivre, le nickel ou le zinc. Un phénomène d'activation faisant intervenir un complexe de coordination entre la glycine et le cation échangeable de l'argile constitue vraisemblablement l'étape intermédiaire dans la formation du peptide.

The present work describes the effect of montmorillonite (MMT) particles on the alignment of conducting polyaniline (PANI) chains in a PANI/MMT composite. The composite was prepared both as a powder, pressed into pellets, and as thin films deposited on glass surfaces. For comparison, pure PANI was also prepared in these two forms. A combination of X-ray powder diffraction analysis and molecular modelling confirmed the successful intercalation of the PANI into theMMT, while Raman spectroscopy confirmed the presence of the conducting form of PANI (i.e. the emeraldine salt) in all samples. Scanning electron microscopy, transmission electron microscopy and atomic force microscopy were used to study the morphologies of all samples. Conductivity measurements showed that the presence of the MMT particles in the PANI/MMT composites contributes to a significant increase in the electrical conductivity in comparison with the pure PANI samples. Moreover, in the pressed pellets the presence of theMMT particles led to an extremely high electrical anisotropy. TheUV-VIS spectroscopy results showed that the PANI/MMT thin film exhibited a selective transmittance in the range 450–650 nm; therefore, the PANI/MMT thin film is not only conductive, but also suitable for use in various optical applications.

A grafted polymer (P(MMA-MAh)-PEGME)) was synthesized by reacting poly(ethylene glycol) monomethyl ether (PEGME) with copolymer of poly(methyl methacrylate-maleic anhydride) (P(MMA-MAh)and end-capping the residual carboxylic acid with methanol. Natural rectorite (REC) was made organophilic by modification with the surfactant dodecyl benzyl dimethyl ammonium chloride. The organoclay was termed OREC and was used as a filler additive to modify gel polymer electrolytes (GPEs) which consisted of the grafted polymer (used as a polymer matrix), propylene carbonate (PC) as a plasticizer and LiClO4 as a lithium ion producer.

The temperature dependence of the ionic conductivity of the GPEs agreed well with the VTF (Vogel-Tamman-Fulcher) relation. 5 phr doses of OREC resulted in the highest ionic conductivity. Using OREC also considerably improved the plasticizer retention levels. As a consequence of OREC occupation of the free volume space in the polymer matrix of GPEs, the bulk resistance of the GPEs was reduced and the glass transition temperature (Tg) increased. From the present research, it can be concluded that the incorporation of PEGME into the copolymer of P(MMA-MAh) produced a great improvement in ionic conductivity, plasticizer retention capability and movement of carrier charge of Li+.

The composition of fluvial waters can be used to predict the processes of formation and evolution of secondary minerals in Galician soils. These processes are similar in areas with different rocks, from acid to basic, the only exception being strongly serpentinized materials. In general, the nature of the rock has less influence than the characteristics of the alteration system, which is always open, acid and freely draining. Mineral neoformation is always of the monosialitic type, having different degrees of evolution. The incipient phases tend to form gibbsite as a more stable mineral, and halloysite, allophanes and imogolite as metastable forms. With time, a crystalline kaolinite would be the only stable species. These results agree with the mineralogy and the andic or ferralic properties of the soils.

Complexes are formed between a Ca-saturated fluorhectorite and organic molecules derived from propane by substituting benzene, pyridine, and piperidine rings in the 1,3 positions. The complexes are mainly of the A- and B-types described earlier by Greene-Kelly. Only one of the substances studied forms long-spacing complexes; in this case, the organic molecule is terminated at one end by a benzene ring and at the other by an active =NH group. Neutral forms of this molecule develop double-layer complexes, cationic forms develop single-layer complexes. The results are consistent with data for alcohols, alkyl chlorides and bromides, and alkyl amines.

The synthesis of kandites in the granites of south-west England has resulted from the breakdown of albite or oligoclase by hydrothermal solutions using joints and faults as channels. The crystallinity of the clay mineral and the extent of argillization are related to the distance from these channels. Intermediate stages between felspar and kaolinite remain obscure but recent evidence suggests that they may be represented by montmorillonite. Little is known about the composition of hydrothermal solutions: fluorine and boron determinations on rocks in various stages of argillization suggest that neither of these elements was an important constituent.