The hydroxyl orientations in the 2H2 polytype of amesite, Mg2Al(SiAl)O5(OH)4, have been determined by minimizing the electrostatic potential energy as a function of OH orientation. The angles, ρ, between the hydroxyls and (001) vary between 81.5 and 88.8°. All surface hydroxyls form hydrogen bonds with oxygens of the adjacent layer. The OHs tend to tilt away from the higher charged A1VI ions, and the spread in ρ values is due to variations in the positions of the receptor oxygens. The inner hydroxyls noticeably weaken the interlayer bonding. The substitution of Al in both T and M sites creates a dipolar layer charge and the resulting attraction between layers forms an important part of the interlayer bonding. The 2H2 polytype of amesite has substantial interlayer bonding even with all surface hydroxyls replaced by fluorine. This is not true for a composition of Mg3Si2O5(OH)4 where a similar F for OH substitution destroys all interlayer bonding as in kaolinite.

Aerogels of clays can be prepared by freeze-drying of clay water gels. The mechanical strength of the aerogels is improved by the addition of water-soluble polyelectrolytes to the hydrogels.

The porosity of the powdered aerogels can be adapted to the requirements for adsorbents in gas chromatography by compounding the hydrogels with suitable amounts of polyelectrolytes. Simultaneously, the surface of the clay may be modified by adsorption of polar or cationic organic compounds in order to achieve specific chromatographic separations.

Because of the toughness of the clay-polyelectrolyte aerogels, they can be rolled out to thin sheets which may be applied as chromatographic papers.

The characterisation, legal status and future of islands are increasingly prominent in international and legal affairs. This emerging ‘legal era of islands’ demands a clearer understanding of the multiple distinctive legal issues that islands, whether as sub-national political units or as the territory of continental or mainland States, raise. This article conducts the first contemporary study of these issues by examining the international and constitutional legal status of island territories. It finds that although the relationship between islands and mainland States is characterised by incredible diversity, island territories are pursuing a range of innovative strategies to preserve and protect their autonomy.

Some authors have stated that anionic surfactants are not adsorbed by montmorillonite while others indicate very minor adsorption. Attempts to quantitatively determine the degree of adsorption have shown that certain problems exist which, unless recognized, will completely mask results. Some of these difficulties have been overcome but exact data have not yet been obtained. However, enough information has been gathered to prove that adsorption of anionic surfactants on montmorillonite is real and substantial. Reliable adsorption data for cationic and nonionic surfactants and one having both nonionic and anionic character have been obtained. It is indicated that 550 mg of these surfactants are adsorbed by 1 g of montmorillonite. X-ray diffraction data for complexes of all surfactants investigated confirm positive adsorption. However, the thickness of the adsorbed surfactant layers cannot always be quantitatively related to the amount of adsorbed surfactant.

The relationships between spectrum and structure in layer-silicates are reviewed, and applied in the study of structural changes occurring during the heating of montmorillonites up to dehydroxylation, and their subsequent rehydroxylation. Information given by infrared spectroscopy on the binding of water in expanding layer silicates is presented, and the physical and chemical processes associated with entry of basic, neutral and acidic molecules into the interlayer space of these minerals are illustrated for ammonia, ethylamine, pyridine, nitrobenzene, and benzoic acid. Problems associated with the study of soil clays, which are often complex mixtures including poorly ordered and amorphous constituents, frequently firmly combined with organic matter, are discussed.

New evidence is presented concerning the environment of the two types of hydroxyl group in beidellite. The thermal stabilities of NH4+ and lattice OH in montmorillonite and beidellite, and the properties of their dehydroxylates, are contrasted. The nature of the collapsed phase formed in Li-, Mg-, and NH4-montmorillonite at 300–500°C is discussed. The presence of weak hydrogen bonds between lattice oxygens and interlayer water is established, although it is shown that the strength of hydrogen bonds formed between NH4+ and lattice oxygens is dependent on the sites of substitution in the layer lattice.

Serpentine- and talc-like garnierites described in Parts I and II were heated at various temperatures up to about 1000°C and after each treatment were cooled and examined by X-ray powder diffraction. The serpentine-like garnierites at about 550°C, the temperature at which rapid dehydroxy-lation begins, formed a highly disordered phase. When the NiO content was low (approximately < 20 wt%), the disordered phase transformed directly to an olivine phase around 800°C, but when the NiO content was higher, various transitional phases were formed before an olivine phase appeared around 1000°C. A sepiolite-like phase was obtained with one sample around 800°C, and several samples showed face-centered cubic modifications between 900 and 1000°C.

The talc-like garnierites with low NiO content formed an enstatite phase around 800°C directly following the dehydroxylation reaction, but with high NiO contents an olivine phase became increasingly prominent between 850 and 1000°C. Identification of the mixed crystallizations possibly existing in the initial minerals is scarcely feasible on the basis of the products formed up to 1000°C.

Electron probe micro-analysis studies on individual particles (40–60 mesh) of weathered micas treated with solutions containing equivalent amounts of Rb and Sr showed partial segregation of these elements. Rb was concentrated at particle and step edges, at cracks, and, in the case of partially K-depleted biotite, at boundaries of vermiculite and mica zones (“wedge zones”). The scarcity of wedge zones in mica from which nearly all of the K had been removed reduced the overall selectivity for Rb. The restricted exchange of interlayer Mg ions from vermiculite-like zones by a mixed Rb-Sr solution was observed in earlier studies with these micas. The proposed explanation for these results was a closing down of the interlayer space at the edge of the particle due to Rb concentration in these positions. This explanation is confirmed by the present study.

The electron structural analysis of a Madagascar sepiolite (Ampandrandava) was carried out by selected area electron diffraction obtained from monocristals. Fourier projections, derived from the experimental intensity of Okl, hOl and hkO reflections, show that the Mg2+ cations on the edges of the sheets are distributed between two sites. Correlatively the water molecules bound to these Mg2+ occupy two distinct positions. These principal structural differences with the Brauner and Preisinger model explain details of the i.r. spectra during the desorption of water or the adsorption of polar molecules. The differences between the two models can be considered as a consequence of treating the mineral in vacuum.

Intercalation compounds of styrene and quaternary ammonium montmorillonite were prepared by immersion of the clay in styrene monomer. The intercalation of stearyltrimethylammonium (CH3(CH2)17N(CH3)3+)-montmorillonite and styrene showed an expansion of the basal spacing to a constant value of ∼32 Å after immersion for 10 days. After polymerization, the amount of polystyrene in the interlayer region was determined by thermal gravimetric analysis. Styrene adsorption initially increased with increasing quaternary ammonium cation and then became approximately constant when loading of the quaternary ammonium cation exceeded 100 meq/100 g clay. The volume resistivity of the stearyltrimethylammonium-montmorilionite-polystyrene complex, which was determined with a high resistance meter, was greater than that of both the quaternary ammonium-montmorillonite and the montmorillonite, and increased in proportion to the amount of polymer adsorbed. These data indicate that polystyrene improved the insulating properties of the clay films.

A quantitative method for determination of montmorillonite in the soil clay fraction, using X-ray spectrometry, is proposed. The method is based on the fact that polyvinylpyrrolidone (PVP) is adsorbed on the interlayer surfaces of montmorillonite, giving a first order c-axis spacing of 26 Å, while it is not adsorbed on other swelling clays. The experimental conditions to obtain a maximum height of the X-ray diffraction peak, and the effect of the mass adsorption coefficient of vermiculite on the intensity of montmorillonite, were investigated. Soil montmorillonite was determined by the method of known additions, measuring the intensity of the X-ray diffraction peak before and after the addition of small and known amounts of Wyoming montmorillonite.

Characteristics and properties of complexes of a smectite (hectorite) with 1,10-phenanthroline (phen) chelates with iron or copper were determined by a variety of physical and chemical measurements. The complex ions showed high selectivity for the hectorite surface. Basal spacings of 17.4 Å were produced by Fe(II) or Cu(II) analogues of M(phen)32+ hectorite. Adsorption of gases and vapors by the M(phen)32+ hectorite complex revealed large surface areas and reflected intrinsic characteristics of the complex ions. Lower surface areas were found for copper phen hectorite than iron phen hectorite probably because of the loss of a ligand from the Cu(II) ion. ESR spectra confirmed that appreciable Cu(II) existed as the bis-phen complex under certain conditions. An increase in the oxidation potential of the Fe(phen)32+-Fe(phen)33+ couple above that in pure solvent was noted when these complexes were supported by the mineral surface.

Inorganic gel and allophane collected from basaltic saprolite on Maui, Hawaii, and studied by Patterson in 1964 were reexamined. The main constituent of the gel is imogolite, and gibbsite and allophane are the minor constituents. Electron and X-ray diffraction patterns, DTA curve, and an infrared spectrum of the gel are characteristic of imogolite. The allophane is virtually noncrystalline to X-rays but contains a small amount of imogolite in relatively short threads. High-resolution electron micrographs indicate differences in structural organization between allophane and imogolite and suggest crystallization of imogolite from allophane.

The occurrence of imogolite as a weathering product has been reported in many localities from pyroclastic materials but not from massive rocks. Probably the exceptionally high rainfall, excellent subsurface permeability of the weathered material, and the low pH and high organic content of the leaching solution provide favorable conditions for formation of imogolite from basalt on Maui.

Major factors affecting the selected area electron diffraction (SAD) patterns of micas are: lattice properties of the crystal, specimen thickness, orientation of the crystal, properties of the Ewald sphere for electron diffraction, depth of field of the objective lens, and variations in focusing conditions of this lens. Depending on these factors, SAD patterns of 2M1 muscovite may display different symmetries. Specimen ’finite’ thickness affects the intensity in terms of the ’interference function’. The latter function has been evaluated exactly and the intensity distribution has been calculated along the (hk) rows. The observed intensity variations of (hk) spots indicate that the focusing conditions of the objective lens are rather critical for the symmetry of SAD patterns.