The structural formula of Kozfikov saponite (Czechoslovakia) is as follows:

$N{a_{0.005}}C{a_{0.22}}{K_{0.01}}[S{i_{3.30}}A{l_{0.68}}F{e^{3 + }}{}_{0.02}][M{g_{2.50}}F{e^{2 + }}{}_{0.26}F{e^{3 + }}{}_{0.24}]{O_{10}}{(OH)_2}.$

Lithium-bearing tosudite was found from a brittle clayey part of the Tooho “roseki” deposit, Aichi Prefecture, Japan. The chemical composition of the Li bearing tosudite was estimated as SiO2 41·60%, A12O3 36·40%, Fe2O3 1·82%, MgO 0·29%, CaO 0·38%, Li2O 1·04%, Na2O 0·14%, K2O 0·38%, H2O+ 11·12% and H2O− 6·87% from the chemical composition of a specimen with associated impurities. The Li-bearing tosudite has the regularly interstratified structure of montmorillonite and dioctahedral chlorite in which Li is present in a gibbsite sheet as shown in the structural formula of interlayer cations K0·16, Na0·09, Ca0.13 + 9·60 H2O; gibbsite sheet Li1·36, Mg0·14, Fe0·45, Al3·59 (OH)12·00; silicate layer Al8·00 (Si13·60, Al2·40) O40·00 (OH)8·00. The 29·48 Å reflection series of the Li-bearing tosudite moves to 31·3 Å after ethylene glycol treatment and to 23·3 Å on heating to 500°C for 1 hr.

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.

On NH4- as well as on (C2H5)3NH-montmorillonite EDA was adsorbed in protonated form. The extent of protonation depended on the relative basicities and concentrations of the interacting compounds. In the systems exposed to EDA vapor a proton transfer process took place. A similar mechanism, involving probably a water molecule which remained associated with the EDAH+ ion, occurred on air-drying (C2H5)3NH-montmorillonite treated with aqueous EDA, whereas no adsorption was observed when the suspension was washed. On the contrary EDA added, in quantities not exceeding the CEC, to a suspension of NH4-montmorillonite was adsorbed almost exclusively as EDAH22+ ion. This is explained in terms of ion-exchange between NH4+ and EDAH+ present in aqueous medium and protonation of the second amine function through the dissociation of water molecules near the clay surface.

Hydrogen-bonding between protonated and neutral EDA was observed when the extent of adsorption was higher than the extent of protonation.

The effect of exchanging selected aryl and alkyl ammonium cations for sodium ions on the morphology and the hydrophobicity of a sodium montmorillonite was studied. It was found that the morphology of the organo-clays as observed by transmission electron microscopy depended on the type of and the amount of exchanged organic cation. An attempt was made to correlate the observed morphology of organo-clays with their hydrophobicity.

This study deals with the analysis of dielectric measurements made on montmorillonites saturated by bivalent cations. These measurements are performed between — 150°C and +30°C at frequencies ranging from 300 to 10,000 Hz. Their interpretation is based on a numerical analysis allowing determination of the dielectric losses due to free charge carriers conductivity phenomena and losses due to relaxation phenomena. The free charge carriers conductivity is due to the movement of protons. It depends very much on the nature of compensating cations and on the water content and seems to be closely related to the characteristics of the swelling.

Two types of relaxation phenomenon are described: a Debye relaxation due to electric dipole rotations and a Maxwell-Wagner relaxation due to heterogeneity effects. The analysis of the first phenomenon leads to the examination of the values of the relaxation time. It appears that the rotations of water molecules are difficult with bivalent cations. This essentially is shown by the high activation energy of the phenomenon. The discussion of these parameters shows that the state of adsorbed water molecules are certainly different as compared to the state of water molecules in ice or in liquid water. The characteristics of the second relaxation phenomenon are closely dependent on the free carriers charge conductivity.

The present paper describes a new mineral species, namely a regularly interstratified chlorite —trioctahedral smectite bearing as much as 24% NiO. The high Ni content proves it to be nickel mineral.

On the diffractogram of the raw sample, an integral series of reflections with l.d(001) = 30·1 Å was obtained. To study the nature of the component layers, X-ray examinations of glycerol saturated samples and also dehydrated by heating were accomplished. Thermal and chemical analyses were performed in the usual way.

The crystallochemical formula can be presented as follows: saponite layer—(Mg,Ni)3·00 (Si3·75Al0·25) O10(OH)2, charge −0·25; Ca0·06 (Mg,Ni)0·06 K0·01, 4·07 H2O, charge +0·25; chlorite layer—(Mg, Ni)2·02(Al,Fe*)0·65(Si3·76Al0·24) O10(OH)2, charge −0·25; (Mg,Ni)2·75 (Al,Fe3+)0.25 (OH)6, charge +0.25.

The full mineral and chemical characteristics lead to precise conclusions concerning the composition and structure not only of the nonexpanding chlorite layers, but especially of the expanding layers. The latter show the chemical composition of saponite but the interlayer material is composed partly of exchange cations and molecular water and partly of “brucite-like pillows”.

Heats of compression of glass bead-water and clay-water mixtures were determined from the peak heights of the thermograms produced when these mixtures were subjected to pressure in a Calvet differential microcalorimeter. It is known that the heat of compression is directly proportional to the peak height. When the latter quantity was plotted against the pressure applied to any mixture, two intersecting straight lines were obtained. The change in slope at the point of intersection was interpreted as being the result of a pressure-induced higher-order phase transition in the water.

The differential peak height, ε, was defined as the rate of change of peak height with pressure/g of water present in the mixture. Hence, it is directly proportional to the rate of change of the heat of compression with pressure/g of water. Values of ε were determined for both glass bead-water and clay-water mixtures containing different proportions of solids. It was found that ε remained nearly constant with increasing proportions of glass beads, whereas, it varied in a non-uniform way with increasing proportions of clay. Also, its values in the clay-water mixtures were relatively high. Calculations showed that the difference in ε values for the two mixtures could not be ascribed to the exchangeable cations associated with the clay particles. Consequently, it was ascribed to the effect of the particle surfaces on the structure of the vicinal water.

The tris(ethylenediamine) complex cations of chromium(III), cobalt(III), and copper(II) were exchanged onto sodium montmorillonite. The resulting cation exchanged clays were dried, ground, sieved and the 50/80 mesh size was retained for use as column packing material to be used in gas chromatographic analysis of light hydrocarbons and oxides of nitrogen. Studies indicated that the hydrocarbons were following a sieving action whereas the nitrogen oxides were involved in a surface adsorption process.

The changes in d001-spacing and surface area of tris(ethylenediamine)Cr(III)-montmorillonite were correlated with the changes in gas chromatographic retention time for the light hydrocarbons and the oxides of nitrogen.

Retention time was obtained for the 100 per cent exchanged montmorillonites containing cations of tris(ethylenediamine)Cr(III), tris(ethylenediamine)Co(III), and tris(ethylenediamine)Cu(II). A comparative study of the d001-spacing and surface area of the three clays is shown to be directly related to the retention time.

Heating effects were studied to determine thermal stability. Changes in retention times were compared with various structural changes. DTA and heating-oscillating X-ray powder diffraction analysis were used to help explain the relationship between retention time and structural change.

Bulk (lump) densities of 31 kaolins were measured on the clay in the natural or raw state after drying at 100°C and after firing to 1510°C (2700°F). The kaolins were selected from such diverse origins as surface-weathered and sedimentary accumulations, hydrothermally altered bodies and flintclay deposits. The sedimentary group ranged in density from 0·82 to 1·85 in the dried raw clay, and 1·93 to 2·63 when fired. The hydrothermally altered clays ranged from 1·83 to 2·50 in the dried raw state, and 2·02 to 2·66 when fired. Flint clays ranged from 2·20 to 2·60 in the dried raw state (a “toasted clay” from Russia, 1.75), and 1·99 to 2·70 when fired. The effect of the genetic process on bulk density values is discussed and related.

Ethylenediamine (EDA) adsorbed from aqueous solution or vapor phase on Al-, Ca- and Mg-montmorillonite was retained to a more or less large extent in protonated form. The NH+3:NH2 ratio decreased with the polarizing power of the mineral exchange cation (Al > Mg > Ca) and with increasing amounts of amine fixed. Excess EDA was adsorbed through hydrogen-bonding with protonated species, and partially through co-ordination in vapor treated samples. Co-ordination to the exchangeable cation seemed to be favored in the order Al > Mg < Ca, and the complexes were stable up to 200°C. Heating lowered the NH+3:NH2 ratio, indicating some deprotonation process caused probably by the competition for protons between EDA and hydrolysed exchange cations. This competition might also account for the rather low quantities of NH+4 produced near 200°C.

A golden-colored, flaky mineral from Morro do Niquel, Minas Gerais, Brazil, gives an X-ray diffraction pattern of a IIb chlorite polytype, with basal spacing 14·21 ± 0·02 Å and b = 9·23 Å. Thermogravimetric analysis shows a progressive weight (water) loss up to 500°C, followed by a rapid weight loss corresponding to dehydroxylation of the interlayer material and a slower weight loss due to dehydroxylation of the 2:1 layer. The structural formula derived from the chemical analysis on the basis of O10 (OH)8, or total cation valence of +28, shows 5·3 total octahedral cations, i.e. probably 2·3 in the interlayers where normally 3 cations are found. This deficiency together with the appreciable loss of water below 500°C suggests a partially vermiculitized interlayer. A new method for deriving the interlayer composition gives R1·67(OH)4·08(H2O)0·59, and a ratio (OH + H2O)/R = 2·80, which approaches that of a dioctahedral interlayer and is consistent with a predominance of R3+ ions. The mineral may resemble the golden, vermiculitized biotite described by Walker and others.

The effects of bending on diffraction profiles and intensities have been directly evaluated. It has been shown that:

1. (1) bending may cause large reductions in intensities or even the total loss of them

2. (2) due to bending, the profile of the reflection may become asymmetrical and it may display two or more maxima

3. (3) bending effects vary with the class of reflections and they become larger with the increasing order of diffraction, and

4. (4) the interference function for a bent lattice must be evaluated for each set of lattice parameters, whereas the interference function for an undeformed lattice can be made invariant with respect to lattice parameters.

The t-plot method has been applied to the results of nitrogen adsorption at 76°K on sepiolite first heated in vacuo at various temperatures. Heating sepiolite samples in vacuo at 427°K results in a large decrease in surface area compared with samples outgassed at 373°K. A change in structure and a consequent collapse of micropores is postulated. However, the t-plots indicate that some microporosity remains. Outgassing at 623°K appears to destroy completely the micropores.

The crystallinity of minerals in terms of crystallite size distribution and lattice perfection is quantified by means of statistical measures derived from X-ray line profiles (2 σ values). A low degree of crystallinity facilitates the non-stoichiometric incorporation of foreign elements in the crystal lattice. Crystallinity is affected by a number of factors and in natural profiles it may vary laterally as well as vertically.

For instance, goethite in laterite deposits shows decreasing crystallinity with increasing depth. Serpentine type minerals, on the other hand, show the lowest crystallinity at the surface where the degree of weathering is the most advanced. The presence of silica in migrating solutions prevents crystal growth and results in a low degree of crystallinity of minerals such as goethite. This has been observed in natural profiles and has been confirmed by laboratory experiments on the synthesis of goethite and sodium-birnessite. The crystallinity of minerals affects their response to extractive procedures. It could also be an important parameter in soil science.

Lysine and vermiculite form a stable, ordered, interlamellar complex which has a well defined superlattice structure with respect to the ab-plane of vermiculite. The lysine molecules lie at a low angle to the silicate surfaces and establish a double layer network between such surfaces. I.R. and chemical data for the complex are given. The possible role of hydrogen bonds in linking the system together is considered.

Fabric refers to the spacial arrangement of clay particles in a sample relative to a reference plane. X-ray diffraction data yield an ‘amount of orientation’ (AO) that varies from zero for ideal random to 100 for ideally oriented fabric. The AO has been related to the average angle of inclination of clay particles to the reference plane.

Fabric data from 50 samples involving 2000 determinations are presented on the effects of: the method of sample preparation prior to one-dimensional consolidation; the magnitude of consolidation stress from 0·1 to over 1000 kg/cm2; changes in direction of consolidation stress; isotropic consolidation; and disturbance during removal of samples from oedometer cells. The single most important variable was the method of sample preparation, as illustrated by the following data on samples consolidated one-dimensionally to 1·5 kg/cm2:clay initially moist, AO = 27 per cent; air-dry clay, AO = 44 per cent; clay slurries, AO = 76–95 per cent. The change in fabric with increasing consolidation stress was most pronounced with samples at very low stresses, the changes in fabric were small for consolidation stress increments usually encountered in engineering practice.

Fabric data provide a very sensitive measure of sample disturbance. Extrusion causes significant disturbance at the center of a 24cm dia, sample cylinder.

A 1–0·2 μm fraction from a soil in the Dominican Republic was studied by X-ray diffraction combined with solvation, cation saturation, and heat treatments. I.R., thermal (DTA, TGA) and chemical analyses were also made. This soil is saline and alkaline and its mineral composition is greatly influenced by the lacustrine parent material and poor drainage.

In addition to swelling chlorite, illite, kaolinite, carbonates and quartz are present in the 1–0·2 μm fraction. The swelling chlorite expanded to over 18 Å when Mg saturated and solvated with glycerol or water. Lower spacings with other cations and ethylene glycol were observed. 1 N HCl treatment partially removed the interlayer hydroxides in the chlorite and 6 N HCl destroyed the mineral. The mineral gave a reflection close to 14 Å up through 600°C but collapsed at higher temperatures to 10·2 Å.

Determination of the mineralogical composition of six highly weathered soils of the Central Plateau of Brazil showed that the sand content (predominantly quartz) was not related to the relative amounts of gibbsite and kaolinite in the clay (< µm) fractions. The latter is in agreement with kinetic considerations of the involved mineral species, but in disagreement with thermodynamic considerations. However, that dissolution of quartz has been operative in these soils is indicated by an excellent relationship (r2 = 0·96) between the amount of sand-size quartz and the reactive SiO2 content of the clay fractions.

Dioctahedral aluminum smectites from bentonite deposits in Argentina, Brazil, Czechoslovakia and Japan represent, according to the MgO content of the bulk samples, intermediate members in the montmorillonite-beidellite series. The smectite particles in these samples occur in a variety of forms such as; (a) laths and diamond-shaped units with a well developed crystal habit, (b) loosely folded aggregates with an irregular morphology and (c) flat and compact lamellae with well developed {001} forms but with complete lack of {hk0} forms. Such lamellae have been described in two groups: the thin ones (10–50 Å) and the thicker ones. Thin lamellae may give SAD spot patterns with a non-hexagonal symmetry. Lamellae having thicknesses greater than 50 Å resemble a single crystal but their SAD patterns indicate that they do not have a three-dimensional periodicity.

The question arises whether the morphologically different particles in a sample belong to the same intermediate phase or if they represent different members in the montmorillonite-beidellite series coexisting in the same sample.