Pillared montmorillonite was used as an adsorbent for binary mixtures of hydrocarbons and alcohols (benzene/n-heptane; ethanol/cyclohexane; ethanol/toluene; propanol/ toluene). The adsorbent was prepared from the Na-form of a bentonite from Milos by reaction with polyhydroxoaluminium solutions. The adsorption behaviour of the pillared montmorillonite was characterized by the adsorption excess isotherms and the heats of immersion. Sorption capacities and wetting properties differed significantly from those of the Na-montmorillonite. Benzene was adsorbed preferentially from mixtures with n-heptane. Ethanol and propanol were also preferentially adsorbed from mixtures with cyclohexane and toluene but the curves showed azeotropic points at molar fractions of alcohols of 0.7-0.9. The calorimetric data revealed the partially hydrophobic character of the pillared montmorillonite. The heat of wetting of benzene or toluene on the pillared samples was distinctly higher than that of ethanol whereas ethanol gave the highest wetting enthalpies on Na-montmorillonite.

A chloritic mineral found in close association with vermiculite from the Yoshino mine, Kochi Prefecture, agrees well with penninite but shows remarkable exfoliation on heating. Its mineralogical properties were studied by chemical, thermal and X-ray methods.

Oxygen isotope analysis of clay minerals presents several practical difficulties. These include their very fine grain size, the presence of both hydroxyl and non-hydroxyl oxygen, adsorbed water and, where clays from oil reservoirs are concerned, the possibility of hydrocarbon contamination. To develop routines which would minimize these problems while leaving the isotope systematics of the clay undisturbed, a series of oxygen isotope analyses were made under different running conditions of the API Standard Illite–the Fithian illite.

Geochemical analysis of acid-insoluble residues derived from white chalks and marl seams of Campanian age from Sussex, UK, has been undertaken. All display a broadly similar <2 μm mineralogical composition consisting of smectite or smectite-rich illite-smectite with subordinate illite and minor amounts of talc. Plots of K2O/Al2O3 and TiO2/Al2O3 indicate that most marl seams have an acid-insoluble residue composition which is slightly different to that of the over- and underlying white chalk, implying that marl seams are primary sedimentary features not formed through white chalk dissolution. On the basis of a negative Eu anomaly and trace element geochemistry one marl seam, the Old Nore Marl, is considered to be volcanically derived and best classified as a bentonite; it is considered to correlate with the bentonite M1 of the north German succession.

The aim of this work was to determine the distribution of trace metals in the coastal sediments from the area between Silifke and Alanya (Turkey) and to investigate the sources of these elements, based on their mineralogical, petrographical and geochemical characteristics. Forty three samples were analysed for the determination of their water content, grain-size distribution, petrographical features and their chemical and mineralogical compositions. The samples had low water content, in agreement with the large sand grain size.

The mineralogical composition reflects the complex geological setting of the area. The most abundant mineral phases are represented by calcite and dolomite, followed by quartz and mica. Chlorite, feldspar and other carbonates are present in lesser amounts, while kaolinite was detected in one sample only. All samples contain hematite, chromite, magnetite and goethite and one sample contained pyrite. Samples with high concentrations of trace metals, contained fragments of metamorphic rocks with pyroxene, amphibole, quartz and feldspar, whereas carbonates and opaque minerals were subordinate. Compared to literature data, the average concentrations of several elements and trace metals were great enough to be considered as possibly toxic, exceeding the Turkish higher acceptable limits. Geochemical data were treated statistically using Principal Component Analysis (PCA) to obtain evidence of their distribution and to identify any correlations.

Based on the distribution of mineral phases, the area investigated was divided into different provinces, each characterized by the abundance of one, or more, tracer minerals. In the westernmost areas, between Alanya and Demirtas, the sediments indicate a provenance from dolomites or marbles. In the area between Demirtas and Gazipasa the provenance was from quartzites, clastic and metamorphic rocks and in the sector between Guney and Anamur, the sediments were derived mostly from low-grade metamorphic rocks, in particular metaschists and metabasites. The sediments in the area between Anamur and Ovacik, display variable source rocks and those between Ovacik and Silifke, were derived from limestones and, subordinately, clastic rocks.

The trace-metal concentrations in beach sands appear to be related to the abundance of silicate minerals derived from weathering of the metamorphic-rock outcrops in the inland mountainous regions. In contrast, the trace-metal contents of the limestone- and dolomite-bearing beach sands were small.

The ODP Leg 171B drilled a transect of four sites at Blake Nose in the NW Atlantic providing an excellent record of the K-T boundary. At the deepest, Site 1049, the boundary is marked by a 9–17 cm thick layer formed mostly of green spherules composed of Fe-rich smectite resulting from the diagenetic alteration of tektites and impact glasses. Minor amounts of authigenic zeolites and palygorskite also occur. This association represents a notable break in the clay mineral composition of Cretaceous and Tertiary sequences. The clay mineral assemblages of the Cretaceous and Tertiary sediments are dominated by inherited clays. Aluminium-rich smectite of pedogenic origin is abundant in both Cretaceous and Tertiary sediments, indicating a relatively warm and hydrolysing climate across the K-T boundary. At Hole 1049A, where the oldest sediments of the interval were analysed, an increase in kaolinite and smectite down core suggests tectonic rejuvenation and distal transport of illite and kaolinite, probably accompanied by more hydrolysing conditions during the late Maastrichtian.

One of the alteration products of a deuteric altered beryl is a high-aluminous chlorite-swelling chlorite regular mixed-layer clay mineral. An attempt was made to calculate the structural formula, and the results of X-ray, differential thermal and electron diffraction analyses are given.

Soil formation has been generally attributed to the interaction of five variables: parent material, vegetation, relief, time, and climate. This interaction may be considered as the impact of the latter four forces on the parent material and the resultant is a profile of weathering that varies with environment. The objective of this paper is to demonstrate how the mineralogical characteristics of soil profiles may be used to determine their genesis.

It is suggested that the source materials of the English Aptian fuller’s earths were soils of the Anglo-Belgian Land and that montmorillonite is the characteristic clay mineral of marine deposits formed when old land surfaces of low relief are transgressed.

La rétention du K par la montmorillonite est liée à une modification de l'ordre de superposition des feuillets élémentaires apparaissant au cours des cycles d'humectation et de dessiccation (HD). A ce sujet deux questions sont évoquées:

• (1) L'importance relative des facteurs expérimentaux mis en jeu: température de séchage et hydratation. Pour un nombre donné d'HD la quantité de K fixé ainsi que les diagrammes de diffraction X et électronique sont indépendants de la température. Le facteur essentiel de la transformation est donc le mouvement de l'eau au niveau interfeuillet.

• (2) Les conditions de libération du K de la montmorillonite et les conséquences de cette libération sur la structure acquise.

L'eau ne pénètre plus dans les espaces interfeuillets de la montmorillonite ayant subi plus de 100 HD; cependant l'éthylène glycol provoque encore une ouverture presque complète à 17 Å, sans pour autant perturber la structure tridimensionnelle.

Des essais d'extraction par différents cations ont montré qu'une fraction importante du K demeure à l'état non échangeable. Mais lorsque la quantité de K extraite atteint 70%, la structure tridimensionnelle est détruite, et l'on revient à un empilement turbostratique.

Huit saponites de synthèse à charge croissante ont été étudiées à l'état ‘zéro couche’ (vide, P2O5) avec différents cations interfoliaires.

On observe—avec le cation K—une croissance linéaire du paramètre b en fonction du taux de substitution Si-Al, mais cette croissance est bien plus faible que celle observée avec les mêmes minéraux hydratés à ‘deux couches’.

On observe par ailleurs pour les cations K, Ba, Rb et Cs des relations linéaires entre les valeurs du paramètre b et de d001 d'une part et le rayon du cation d'autre part. Les cations plus petits (Na et Li) conduisent à des solutions structurales différentes. Avec le sodium la structure 1 M n'est plus conservée, les feuillets sont décalés les uns par rapport aux autres. Avec le lithium, le type d'empilement 1M est conservé mais c'est l'entité Li+-H2O qui est piégée dans les cavités ditrigonales placées face à face.

L'ensemble de ces résultats permet de montrer que les interactions entre touche interfoliaire et feuillets sont beaucoup plus fortes dans l'état ‘zéro couche’ que dans les états hydratés à une ou deux couches d'eau. Ces interactions sont fonction du rayon des cations interfolaires et peuvent entraîner une rotation des tétraèdres, ce qui conduit à discuter de la validité des équations donnant l'angle de rotation α en fonction de la composition des phyllosilicates.

An expert system has been designed for the structural characterization of disordered phyllosilicates as well as the mixed-layer minerals and the minerals containing stacking faults or isomorphic substitutions. X-ray diffraction being the simplest tool for structural characterization, the expert system uses such data but can account for data provided by any characterization technique (infrared spectroscopy, EXAFS, etc.). The expert system aims to summarize in a unique set the different approaches of the structural characterization using diagrams or tables which have been proposed, avoiding the requirement of the knowledge of their application field and excluding calculations. It runs in an interactive way, to mimic the way a human expert would draw its conclusions.

The distribution and origin of clay minerals in Carboniferous sandstone reservoir rocks, onshore and offshore UK, is reviewed using both published and unpublished sources. The clay mineralogy for many of the Carboniferous reservoir sands tends to be similar, with the detrital clays predominantly illitic whereas the diagenetic clay assemblages are dominated by kaolin with usually lesser amounts of illite. The main exception to this pattern is found in the Dinantian sandstones of the Clair Basin where significant amounts of smectite are present. Three stages of diagenetic kaolin formation are widely recognized. Firstly eogenetic and/or telogenetic kaolinite; secondly mesogenetic kaolin; and thirdly the partial or complete transformation of kaolinite to dickite during deep burial. In addition to the formation of diagenetic clay phases, the sandstone reservoirs also display a complex diagenetic history involving cementation and dissolution processes. These have affected the reservoir properties of the sandstones but the depositional facies architecture still exerts a major recognizable influence on reservoir porosity-permeability characteristics. The abundance of kaolin cements shows no clear correlation with variations in porosity and permeability for Carboniferous reservoirs. Pore- filling smectite affects reservoir porosity and permeability in the Dinantian of the Clair Field, and could be a potential source of serious reservoir damage arising from swelling.

Fe-rich dioctahedral smectites are the main constituent of clays in Çamlıca Region of Turkey. The structural, chemical and morphological characteristics of these smectites after washing are examined by X-ray diffraction, electron microscopy, inductively coupled plasma mass spectrometry and Fourier transform infrared spectroscopy. Smectite particles occur as individual flakes 0.2–2.0 μm in size. These flakes are often aggregated into clusters up to 6.0 μm in size.

Tritium accumulation in clay minerals (kaolinite, montmorillonite, palygorskite) was studied experimentally over a one year contact with tritiated water (initial activity 1.676x109 Bq/m3) under room conditions, and was compared to theoretical calculations. The amounts of tritium ions in bound water and structural hydroxyls were measured by the activity of water fractions released at characteristic temperatures determined on the basis of the mineral DTA patterns. Experiments showed that after a 400 day contact with tritiated water, tritium exchange rates (θ) were highest in palygorskite (θa = 0.42 in bound water and θs = 0.51 in the structure) compared to montmorillonite (θa = 0.15 and θs = 0.11, respectively) and kaolinite (θa = 0.34 and θs = 0.02, respectively). This could be due to different tritium concentrations in the solution near the bound-water layers, and also to certain features of the mineral structures, most of the kaolinite structural hydroxyls not interacting directly with bound HTO molecules.

Tritium accumulation in these minerals, under room conditions, can be described by a relatively simple two-stage isotope exchange model in which tritium ions first migrate from the solution to the bound layers and then substitute the protons of the structural hydroxyls. Rate constants for both stages of this isotope exchange were calculated on the basis of the experimental data.

L'examen des textures de kaolins au M.E.B. apporte des données complémentaires utiles pour la compréhension de leur genèse. Les kaolins provenant d'une altération météorique ont une texture poreuse constitutée par de gros paquets de plaquettes hexagonales empilées de façon lâche ce qui les différencie nettement des kaolins d'origine hydrothermale dont la texture est compacte et la porosité faible. Les kaolins sédimentaires montrent une association de petites plaquettes accolées les unes aux autres quand on les volt suivant les plans de clivage, ou présentent une orientation plus ou moins marquée dans la direction perpendiculaire. Enfin I'observation des textures permet de mesurer I'influence et I'importanee de la diagenèse dans les dépôts argileux.

Three samples of terra rossa were shown to be efficient adsorbents of phosphate [P(V)] from wastewater and removed 29.9–32.6% of P(V). The total iron content in terra rossa was the key factor which determined the P(V) removal from wastewater. The original samples of terra rossa were effective support materials for the immobilization of metabolically active P(V)-accumulating bacteria Acinetobacter junii (0.56–2.47×1010 CFU g–1). The removal of oxalate-extractable iron from original sample of terra rossa increased the number of immobilized bacteria to 1.34×10–11 CFU g–1, which is the largest number of immobilized bacteria reported in the literature so far. In reactors containing the A. junii and terra rossa P(V) was removed from wastewater by simultaneous adsorption onto terra rossa and accumulation inside bacterial cells, resulting in 40.5–62.5% of P(V) removal. Terra rossa is a promising substrate for biological P(V) removal from wastewater, acting both as adsorbent of P(V) and carrier of P(V)-accumulating bacteria.

Seven diagenetic illitie clays have been investigated by Mössbauer spectroscopy to characterize the forms of iron. Four specimens had measurable amounts of iron oxide impurity phases, accounting for up to ∼95% of the total Fe. Goethite, microcrystalline and probably aluminous, was identified as the oxide phase in three of these samples, the other containing hematite. This latter sample was also the only one which had tetrahedral Fe(III). Five of the samples contained measurable amounts of Fe(II), but the aluminosilicate Fe was present largely as 6-coordinated Fe(III) which had two distinctly different sets of parameters. These results are discussed in terms of the structural properties of illites.