Spray drying dilute suspensions of bentonitic montmorillonite produces a powder that shows totally random orientation of the crystallites within a sample large enough to diffract X-rays. The powder is collected by an electrostatic precipitator and can be handled in the normal mounting processes without introducing preferred orientation. Electron micrographs show this powder to be composed on a small scale of thin, crumpled, and rolled films. The extremely small montmorillonite crystallites that make up the film are oriented with [001] directions perpendicular to the film surface. Orientation within the plane of the film is random as shown by selected area electron diffraction. Crumpling and rolling of the film is sufficient to make the orientation of [001] directions random in three dimensions in a large sample when X-ray diffraction is registered.

The X-ray diffraction patterns all show diffraction maxima (both hk and 00l), and their relative intensities with respect to each other can be determined. The line broadening of the 06 and the 003 peaks was studied. The average crystallite size as calculated from the line broadening varied from six to eleven unit layers thick for four bentonitic montmorillonites. The average lateral dimension of crystallites varied from 140 Å to 250 Å. Ratios of lateral dimensions to thickness varied from 2.3 to 3.4.

Clay fractions from four soils were analyzed for kaolinite and gibbsite by differential thermal analysis (DTA) and selective dissolution analysis (SDA). The kaolinite values by the two methods had a standard deviation of ±0.95 for the 2–0.2 μ clay of the three most highly weathered soils. Apparently some kaolinite was dissolved with amorphous material in the 0.2–0.08 μ kaolinite standard and probably in 0.2-0.08 μ soil clays. Accuracy of kaolinite determination for the 0.2–0.08 μ soil clays by DTA was reduced because of uncertainty of exact composition of the standard. Presence of montmorillonite in Sango soil clays, particularly the 0.2-0.08 μ fraction, apparently contributed to the error in kaolinite determination by SDA. More precise values for gibbsite were obtained by DTA than by SDA because of the dissolution of alumina from sources other than gibbsite.

The loop space of a string manifold supports an infinite-dimensional Fock space bundle, which is an analog of the spinor bundle on a spin manifold. This spinor bundle on loop space appears in the description of two-dimensional sigma models as the bundle of states over the configuration space of the superstring. We construct a product on this bundle that covers the fusion of loops, i.e. the merging of two loops along a common segment. For this purpose, we exhibit it as a bundle of bimodules over a certain von Neumann algebra bundle, and realize our product fibrewise using the Connes fusion of von Neumann bimodules. Our main technique is to establish novel relations between string structures, loop fusion, and the Connes fusion of Fock spaces. The fusion product on the spinor bundle on loop space was proposed by Stolz and Teichner as part of a programme to explore the relation between generalized cohomology theories, functorial field theories, and index theory. It is related to the pair of pants worldsheet of the superstring, to the extension of the corresponding smooth functorial field theory down to the point, and to a higher-categorical bundle on the underlying string manifold, the stringor bundle.

Mineralogy, O18/O16, and D/H ratios have been determined in five size fractions (<0.1, 0.1–0.5, 0.5–1.0, 1.0–2.0, and >2.0µm) of seven samples taken from 500 m of Pleistocene deep-sea sediments cored at Deep Sea Drilling Project Site 180 in the Aleutian Trench. The depositional age of the samples spans the last 300,000 years; the samples have been interpreted by others to be continental detritus weathered from a mixed igneous, metamorphic, and sedimentary source area and then deposited by ice-rafting and turbidity currents. The minerals present are quartz, feldspar, illite, chlorite and/or non-expandable vermiculite, and expandable vermiculite and/or mixed-layer illite/expandable vermiculite. The relative amounts of quartz, feldspar, and total clay vary with particle size, but are nearly constant from sample to sample for a given particle size. δO18 is values of the four coarser size fractions range from +9.7 to +12.0‰ with variations attributable to changes in quartz/feldspar and clay/(quartz + feldspar) abundances. Values of δO18 for the expandable vermiculite-rich <0.1-µm size fraction range from +12.1 to +16.3‰ which indicates some oxygen isotope exchange at surface temperatures between meteoric waters and the parent rock during vermiculite formation. Values of δD range from −46 to −74‰ with variations attributable to changes in amounts of different clay minerals present. There is no mineralogic or isotopic evidence of post-depositional reactions in the coarser size fractions, but a general change in δD of the vermiculite-rich, <0.1-µm size fraction from about −50‰ to about −70‰ with increasing depth may be due either to post-depositional isotopic exchange or to climatic changes in the terrestrial weathering environment.

Aluminum is treated as a mobile, reactive component in newly designed stability diagrams for the SiO2-Al2O3-K2O-H2O system. The diagrams show that the stability field of kaolinite is strongly dependent on pH at or below 6·7 but at 6·7 or greater the stability field is independent of pH, and also that in present sea water, K-mica is a stable phase with respect to kaolin minerals. Natural waters from present-day, kaolin-forming localities in Mexico and Kentucky are consistent with theoretical interpretations from these stability diagrams.

A review of mineralogical and geochemical studies on Recent sediments indicates that the clay fraction of marine sediments is not in isotopic or chemical equilibrium with the oceanic reservoir and will not reflect the chemical environment of deposition. Consideration of the sedimentary geochemistry of the alkali metals suggests that fractionation of these elements, which may be one of the major features of the chemical evolution of ocean water, occurs in the terrestrial weathering environment during the formation of clay minerals and in the subsurface environment during clay mineral diagenesis. It is proposed that during the initial stages of oceanic development the Na/K ratio of ocean water was adjusted to a value of forty to fifty by the extensive diagenesis of the existing natural water. With an increase in oceanic volume and a major change in the hydrologic cycling of natural waters the chemical evolution of alkali metals in ocean water has now become primarily controlled by mixing with continental drainage water.

The rates of K exchange of untreated and peroxide-treated micaceous clays from five Podzol soils of increasing degrees of weathering were determined using sodium tetraphenyl boron. In addition, the amounts of K fixed against NH4 were measured. The Ae horizon clays of these soils contained mainly interstratified mica-vermiculite-montmorillonite whereas the C horizon clays contained mica of a more discrete nature.

As was expected, there was an inverse relationship between rates of K exchange and degrees of weathering of the Ae horizon clays. However, in the samples from each of these soils except in those of the most weathered one, the K exchange rate of the interstratified mica from the Ae horizon was higher than that of the less weathered, more discrete mica from the corresponding C horizon. The abundance of hydrated edges and layers exposing K exchange sites in the Ae horizon micas probably contributed to their higher rates of K exchange. Amounts of K fixed in the Ae horizon clays were not related to degrees of weathering.

Removal of organic matter from the Ae horizon clays by peroxide considerably increased both the rates of K exchanged and the amounts of K fixed. These increases were attributed to the elimination of a blocking effect of adsorbed organic matter on K exchange and fixation.

Until now, the different attempts to describe the defects of kaolinites were based on the ideas that (i) the hkl reflections with k = 3n are Bragg reflections, while (ii) the hkl reflections with k ≠ 3n are affected by ±b/3 translations or ±2π/3 rotations. With regard to this conception, this work provides several important precisions: (i) The h, 3n, l′ reflections are true continuous diffraction bands, more or less modulated, and disturbed by the existence, in the stacking, of random shifts parallel to the layer plane. (ii) The major defect in natural kaolinites is not the ±b/3 translation, but the displacement from one layer to the other (or from one domain to another in the same layer) of the Al vacancies. (iii) The model containing true rotation of layers should be rejected because it does not allow us to interpret all the different parts of the experimental diagrams. Such a concept of defects in kaolinites is in agreement with the existence of polytypes of kaolinite, with the presence of twins, and allows us to interpret some physico-chemical properties such as the infrared spectra.

Oxidation of octahedral ferrous iron in biotite by saturated bromine water results in a loss of both octahedral and interlayer cations. The hydroxyl adjacent to vacant octahedral cation sites adopt an inclined orientation resulting in a more stable environment for interlayer cations. The only structural change accompanying these processes is a decrease in b-axis dimension which is linearly related to octahedral ferric iron content. These findings are in agreement with observations made on naturally weathered biotites.

Some dehydroxylated sericites were boiled with solutions of various salts. A rectorite-like regular mixed-layer was formed when 2M sericite was treated with solution containing salts such as NaNO3, Na2SO4, CaSO4, CaCl2, MgCl2 and MgSO4 respectively. A random mica/montmorillonite mixed-layer was formed from 1M sericite. In order to change the 2M sericite into a regularly interstratified mineral, they are heated to the temperature range of dehydroxylation. The formation of a regularly interstratified mineral from 2M sericite can be explained by the change in the (OH) bond direction after the extraction of the potassium ion.

Ion exchange analyses of the clay-sized fraction of sediments in Lakes Pontchartrain and Maurepas suggest the selective adsorption of Na at the expense of Mg. The literature suggests that Mg should be preferentially adsorbed. As the chlorinity of the lake waters increases from 300 mg/l to 3250mg/l, the percentage of exchangeable Na increases from 13·6 to 30·6 while the percentage of exchangeable Mg decreases from 65·6–36·8. The observed exchangeable Na percentages are higher than the ones calculated from the sodium-adsorption-ratios. The difference is attributed to an increase in the Na exchange constant of the sediment and therefore an increased selectivity for Na. With an increase in chlorinity, montmorillonite increases from 47 to 61 per cent and the total of the exchangeable cations (Na, Mg, Ca, K) increases from 36 to 82 m-equiv./100 g.

Transmission and diffraction electron micrographs were made of illite and montmorillonite to study the changes that take place as the clays were heated continuously to 1200°C.

In both of the clay minerals studied, expulsion of a highly fluid material occurred subsequent to dehydroxylation and prior to the development of the first-formed high temperature phases. It was hypothesized that this material represented the expulsion of constituents in the clay in excess of those needed for the formation of the first high-temperature phase. Electron diffraction indicates that the high-temperature phases that formed all developed with some preferential orientation, and were strongly influenced in their development by the structure of the original clay.

The new species Caloplaca tswaluensis is described from Tswalu Kalahari Reserve, Northern Cape Province, South Africa. Caloplaca tswaluensis occurs on the trunks of Vachellia erioloba (camelthorn) trees and is characterized by its 3-septate to quadrilocular ascospores. Molecular data indicate that the new species is placed in the subfamily Teloschistoideae but cannot be assigned to any existing genus and, because its systematic position is unclear, we choose to describe it in Caloplaca s. lat. Caloplaca tswaluensis is compared with other crustose Teloschistaceae species with plurilocular ascospores.