Large hydrothermal deposits of halloysite clay occur in the Terraced Hills, Washoe County, Nevada and similar bodies probably are present elsewhere in the Basin and Range province. The host rock, an andesitic tuff, is underlain and overlain by volcanic flows; all these rocks are late Miocene to Pliocene in age. The clay bodies are composed mostly of halloysite with some iron oxides, variable amounts of feldspar and quartz, and locally some montmorillonite. Commonly all the pyroclastic unit is altered to halloysite material. In one locality, however, the halloysite body is restricted to the upper part and it is in sharp contact with underlying, partly montmorillonitized tuff. The contact of a clay body with the overlying basalt is distinct. Generally some halloysite is present in the lower part of the basalt and montmorillonite occurs in both materials near their contact. The solutions that altered the tuff were generated during volcanism, rose along high-angle faults, and were restricted to the permeable and otherwise favorable vitric tuff by the capping of relatively impermeable basalt.

Woolly erionite from the Reese River deposit, Nevada, is identical in appearance to that at the type locality, near Durkee, Oregon. Both of these erionites differ in appearance from all other erionite reported in the past 20 years from diverse rocks throughout the world which are described as prismatic or acicular in habit. The non-woolly erionites are especially common as microscopic crystals in diagenetically altered vitroclastic lacustrine deposits of Cenozoic age. The Reese River woolly erionite fills joints in gray to brownish-gray lacustrine mudstone of probably Pliocene age, in a zone about 1 m thick beneath a conspicuous gray vitric tuff. Compact masses of long, curly, woolly erionite fibers are in the plane of the joint and locally are associated with opal. Indices of refraction are ω = 1.468 and ε = 1.472; hexagonal unit-cell parameters are a = 13.186(2) Å, c = 15.055(1) Å, and V = 2267.1(0.9) Å3. A chemical analysis of woolly erionite yields a unit-cell composition of: Na1.01K2.84Mg0.3Ca1.69Al8.18Si27.84O72·28.51H2O.

In February 2011 the Brunel Sound Series hosted Phill Niblock at Brunel University London, a memorable visit expertly orchestrated by our late colleague Bob Gilmore.1 The occasion featured Phill's Disseminate and the premiere of his TWO LIPS aka Nameless, led by Bob. As an amateur clarinet player, in an ensemble made up of Brunel staff and students, I had the privilege of delving into the intricacies of Niblock's compositions. The event marked a significant chapter in our music department's history, with performances at Brunel University and, a day later, at London's trendiest club for hip contemporary music, Cafe OTO, in Dalston, leaving an indelible imprint on our students’ musical journey, and not just theirs.2

The adsorption of Sn(IV)TPyP (mesotetrapyridylporphyrin) in sodium hectorite was studied using ultraviolet-visible and luminescence spectroscopy. The adsorbed complex was found to demetallate forming the TPyP dication as the clay is dehydrated. This process was found to be reversible indicating that the Sn4+ ion remains in the vicinity of the porphyrin upon demetallation. The luminescence spectrum of the adsorbed complex was found to be a composite of the Sn(IV)TPyP and the dication spectra. The presence of a band at 750 nm in the luminescence spectrum of the adsorbed species suggested an enhanced interaction between the π-systems of the pyridyl substituents and the porphin nucleus. This is believed to result from a decrease in the dihedral angle between the nucleus and the substituents when they are squeezed between the clay sheets.

Data on montmorillonite and illite collected by A. Kahn were further analyzed to show the relationship between particle geometry and the optical density (OD) of the clay suspensions. A correction was introduced to the calculations of the minor dimension of the montmorillonite particles which took into account the volume of water between unit layers.

The assumption of disc geometry which was used by A. Kahn in the calculations of the clay particle dimension was found to be consistent with his OD measurements, thus showing that optical measurements can be used to find an equivalent radius of montmorillonite and illite when the general geometry of the particles is the same.

Gerald Barry's approach to composition has undergone a number of changes. Frequently these developments coincide with the composition of a large-scale opera. One of these points of transition in his output occurs in the period before he commenced work on The Bitter Tears of Petra von Kant. Between 1999 and 2000 Barry composed three works – 1998, The Eternal Recurrence and Wiener Blut – in which he attempted to find a new compositional direction after a period in which canonic proliferation dominated his musical material. This article examines some of the main traits of these works, and Wiener Blut in particular, since it contains a greater variety of approaches than the other two compositions. The article also considers how Barry's shift in approach may have been linked to his decision to set Rainer Werner Fassbinder's play. Its quite plain, realistic prose was a contrast to the sort of text Barry had previously chosen to set, requiring a different musical response, and the article draws out some possible connections between Barry's three ‘pointillistic’ compositions and the opera.

An electrooptic birefringence technique was employed to study the effect of particle size, saturating cation, and clay type on the rotational diffusion coefficient (a measure of the rate at which the particles rotate or relax within the solution) from a preferred orientation. These studies help elucidate the nature of the cation—water environment near the clay particles.

Previous work has shown that some clay particles orient at both low and high voltages due to a permanent dipole and an induced dipole, respectively, whereas other clays under similar short-duration pulses orient only at high voltages. The permanent dipole was attributed to the iron in the octahedral layer of the clay mineral, whereas the induced dipole was probably due to a redistribution of the diffuse double-layer cations. This study shows that smaller clay particles orient more readily at low voltages and have greater rotational diffusion coefficients at high voltages. The higher the rotational diffusion coefficient, the faster the particles move in their surrounding water-cation environment. The effect of the saturating cation on the rotational diffusion coefficients was Na > Li > K for the permanent dipole and K > Li > Na > Ca > Mg for the induced dipole orientation. Previous results (Schepers and Miller, 1974) are interpreted to mean that a particle in dilute suspension can rotate independently of its environment only when the salt concentration in the surrounding medium approaches zero. At higher salt concentrations, or if the particle environment is perturbed by an electric field, the particle rotates with a water shell. As the concentration of salt or strength of the electric field increases further, either the viscosity of the surrounding solution increases or the size of the rotating shell is greatly increased. Thus, the water around clay particles appears to be structurally different than normal, and this condition is probably caused by the nature of the clay—cation interaction.

The conductivites of the Na and H ion-exchanged forms of kaolinitic clay rejects from sand-washing operations, both purified and as found naturally as a complex with soil organic matter, were examined. The two Na-clays showed linear conductivity-concentration characteristics, each having two regions with different slopes intersecting at ∼3.3% by weight of clay, which probably reflect a structural change from sol to gel. In the gel region, only the Na-counterions conducted, the reduction in conductivity with concentration being due to a smaller proportion of these ions in the Gouy layer and/or a decrease in their mobilities. In the sol, an additional, concentration-dependent conductivity arose from the electrophoretic motion of clusters of clay particles which gradually broke down on dilution. The two acid clays showed curved conductivity-concentration characteristics consistent with a weak acid dissociation equilibrium; the pKa values of 6.37 to 6.56 are close to those determined independently from titration with alkali. A stronger acid species detected in the titrations was not seen in the conductivity. The MOH2+/MOH/MO− model of the clay-surface species and one set of the predicted concentrations of each species (see preceding paper) are consistent with the observed conductivities. The MOH2+ species probably bridged the edges and faces of clay particles so that the H atoms were identical, but became different when alkali was added.

Structural Fe2+ in montmorillonite is readily oxidized by contact with water, salt solutions or on mild heating. This is shown clearly by the Mössbauer spectra and is associated with a sharpening of the infrared absorption near 880 cm−1. It was inferred that this band comprises the Fe2+—OH—Al and Fe3+—OH—Al deformations. The rate at which oxidation occurs depends on the exchangeable cations. High acidity of the interlayers is conducive to oxidation, as is contact with Cu2+-containing solutions or concentrated H2O2 solutions.

The results show clearly that any chemical treatment of montmorillonite causes changes in the oxidation state of structural iron.

Previously reported deposits of kaolin of hydrothermal origin in Mexico have been described from igneous parent rocks dominantly extrusive in occurrence. Recently observed evidence from other localities confirms an intrusive mode of occurrence, however, for hydrothermally kaolinized agglomerate and tuff within limestone host rock. Three such occurrences have been recognized near Jasso-Calera, north of Mexico City, and near Coacoyula, Guerrero, and Sombrerete, Zacatecas.

The contacts of these clay deposits with limestone show regularly a concentration of iron-rich minerals such as red to brown oxides and/or nontronite, but less commonly an irregular development of grossularite, and bands or pockets of endellite. Silica gossans indicate that hypogene altering solutions were active into the current geomorphic cycle. Kaolinite at the center of the clay body and endellite at the border zones are interpreted as originating, respectively, from in situ alteration of solid rock and deposition from ambient solutions.

Scan electron micrographs are shown of the textures of flint clays, tonsteins, kaolin associated with combustion-metamorphism, sedimentary kaolin, and dickite from the Sydney Basin of Australia. The textures of the flint clays and tonsteins indicate those clays were derived largely from volcanic products. The clay samples were collected at stops on the Kaolin Excursion No. 4 of the August, 1976, International Geological Congress.

In like manner, kaolin samples were collected in Japan from stops made on the field excursions of the Seventh Conference of the Committee on Correlation of Age and Genesis of Kaolin which met in Tokyo, September, 1976. SEMs illustrate representative kaolins of Japan, including Gaerome and Kibushi types of kaolin, Roseki (‘wax stone’) pyrophyllite and dickite, hydrothermal kaolin at Itaya, and flint clay at Iwate. Varied morphologies of halloysite, including spherical halloysite, from the Yamaka open-pit at Naegi are micrographed.

Word descriptions of the textures are frustratingly inadequate in comparison to what may be seen at a glance in the micrographs—hence, the abstract becomes in reality a rapid view of the SEMs.

Analytical data from aqueous dissolution studies of minerals, mineral systems, and naturally equilibrated solutions such as surface waters and groundwaters provide the basic ingredients necessary to calculate comparative solubility (or activity) products (CKs) and comparative free energies of formation (CΔGf0) of possible minerals or hypothetical minerals. Using a thermodynamic approach, quasi-thermodynamic values are obtained which can help in understanding the relative stabilities of different but similar materials and changes in reacting systems. Illite equilibrated solutions demonstrated that: 1) there is a 5 kcal spread in comparative free energies of formation of the five illites used, 2) the comparative stabilities remain about the same when highly simplified but similar hypothetical mineral formulas are considered, and 3) some of these illites are probably not the most stable phase in a closed chemical system at standard temperature and pressure.

A “mineral index system” composed of common rock-forming minerals, products of chemical weathering and perhaps hypothetical minerals is proposed, which offers a means of studying naturally equilibrated solutions. Such a system can show changes with respect to CΔGf0 of these minerals at a particular site through time or in relationship to spatial distribution and geologic changes through synchronous sampling at different sites.

This article argues that John’s christology affirms the material visibility of God by reconciling the notion of an “unseen” God to the visibility of the Father that Jesus presents. Three pieces of evidence support this claim. The first is that “unseen” and “invisible” are not synonymous. A survey of Second Temple, biblical, and rabbinic literature reveals that one may not assume that all hellenized Jews embraced Platonist notions of invisibility. Second, Jesus presents the Father as visible, however restricted that visibility may be to Jesus’s person. Third, John’s use of Isaiah suggests that the visibility of God in the theophanies is consonant with God’s visibility in Jesus.