Analysis of Mossbauer effect in layer silicates provides a spectroscopic method for determining valences and coordination of iron. In this study Mossbauer spectra were obtained for amesite, cronstedtite, nontronite, two glauconites, biotite, lepidomelane, chlorite, minnesotaite, vermiculite. stilpnomelane, and chloritoid.

Trivalent iron was detected in tetrahedral coordination. Abundant trivalent iron in octahedral coordination apparently causes quadrupole splitting values of divalent iron in the same mineral to decrease. This phenomenon was noted in cronstedtite and glauconite. In cases where divalent iron predominates in the mineral, the quadrupole splitting is larger. It is generally accepted that ferrous iron is largely in octahedral coordination. This suggests that the octahedral sites may be more distorted when ferric iron is present in the octahedral sheet. In biotite, quadrupole splitting of divalent iron is decreased when trivalent iron is present in tetrahedral sheets. This suggests that there is also more distortion in the octahedral sheet because of iron in tetrahedral positions.

Retention of basic components of a crude oil by clay-containing reservoir sandstone was studied by flowing crude oil through cores and monitoring the concentration of bases in the effluent. Cores that were H-saturated, H-saturated then aged, and Na-saturated retained 0·82, 0·82, 0·70, and 0·20 meq base/100 g, respectively. Barium exchange capacity values were 0·86, 0·71, and 0·83 meq/100 g. Subsequent floods with water, toluene, and chloroform-acetone removed oil that had increasing concentrations of base and N, indicating that the basic fraction of crude oil was the most difficult fraction to extract from clay mineral surfaces. Retained bases were nitrogenous and the most tenaciously held bases had base/N ratios approaching unity.

Interlayers were produced in montmorillonite, vermiculite and hectorite in aqueous suspensions by precipitation from metal chloride salt, by hydrolysis of metal amalgams, and by slow hydrolysis of metal acetate during refluxing. In several systems an external phase of bayerite, gibbsite, or brucite was also formed. A prominent high frequency OH stretching vibration is associated with the interlayer in montmorillonites with approximate frequencies of 3660 cm−1 with nickel interlayers, 3690 cm−1 with aluminium interlayers and 3710 cm−1 with magnesium interlayers. Pleochroism studies indicate transition moment of interlayer OH to be at a relatively high angle to the planar surface of the clay crystals. Aluminium interlayers show some evidence of an additional weak absorption in the lower frequency region of 3570–3600 cm−1. In differential studies the lower frequency absorption is more evident and is shown to be unaffected by orientation. Techniques involving balancing of water deformation bands in differential spectra and D2O exchange suggest that it is not a water band. D2O flushing to remove water leaves the low frequency interlayer OH band more prominent in hectorite where the clay crystal OH is at 3680 cm−1. Deuteration studies show that flushing with D2O at room temperature removes water, and heating at 100°C in D2O vapor exchanges interlayer OH but not the clay crystal OH. Study of the OD stretching of the systems with deuterated interlayers supports observations made in the OH stretching bands.

Equilibrium studies on clay films exposed to NH3 and H2O vapors demonstrate the effect of exchangeable cations on surface acidity and its relationship to hydration. At a relative humidity of 98 per cent the order of acidity on the clay surface as indicated by protonation of NH3 was Al > Mg > Ca = Li > Na = K for Wyoming bentonite and Al > Mg > Li > Ca = Na = K for nontronite. At a relative humidity of 20 per cent, however, the order was Al = Mg > Ca > Li > Na > K for the bentonite and Al = Mg > Li > Ca > Na > K for nontronite. The largest change in proton donation properties due to hydration effects was in the calcium clays. For Ca-bentonite the NH4+ formation was 16 me/100 g at 98 per cent and 80 me/100 g at 20 per cent relative humidity. In Ca-nontronite, the NH4+ formation was 14 and 64 me/100 g for the wet and dry systems respectively. The differences in proton donation between the bentonite and nontronite clays are believed to be due to charge site location and its effects on ion hydration. The NH4+ formed by the protonation process seemed to exist in different environments in the bentonite and nontronite as indicated in the i.r. absorption spectra.

A kaolin bed in which many of the individual kaolinite platelets exceed 0·2 mm in size occurs in the immediate vicinity of the base of the middle-Miocene Kirkwood Formation, near Woodstown, New Jersey. These platelets appear to have resulted from breakdown of pre-existing illite and montmorillonite coupled with concurrent epitaxial growth and diagenetic growth of primary kaolinite. The alteration of the clay minerals is thought to be a product of upward leaching (dialysis) by groundwaters in the underlying Vincentown Sand. This is further evidenced by abnormally high percentages of clay-size kaolinite in the clays that lie above the Vincentown Sand but beneath the macro-kaolinite horizon. Growth of the macro-kaolinite was facilitated by face-to-edge sédimentation and the resultant high permeability of the stratum.

Previous investigations have demonstrated the influences of interlayer cation composition, relative humidity, temperature, and magnitude of interlayer surface charge on the interlayer hydration of montmorillonites and vermiculites. It has been suggested that the sites of layer charge deficiencies may also have an influence upon the amount of hydration that can take place in the interlayers of expandable clay minerals, if the interlayer cation-to-layer bonds are considered as ideally electrostatic, the magnitude of the forces resisting expansion may be expressed as a form of Coulomb’s law. If this effect is significant, expandable structures in which the charge-deficiency sites are predominantly in the tetrahedral sheet should have less pronounced swelling properties than should structures possessing charge deficiencies located primarily in the octahedral sheet.

Three samples that differed in location of layer charge sites were selected for study. An important selection criterion was a non-correlation between tetrahedral charge sites and high surface-charge density, and between octahedral charge sites and low surface-charge density.

The effects of differences in interlayer cation composition were eliminated by saturating portions of each sample with the same cations. Equilibrium (001) d values at controlled constant humidities were used as a measure of the relative degree of interlayer hydration.

Although no corrélation could be made between the degree of interlayer hydration and total surface-charge density, the investigation does not eliminate total surface-charge density as being significant to the swelling properties of three-sheet clay-mineral structures. The results do indicate a correlation between more intense expandability and predominance of charge deficiencies in the octahedral sheet. Conversely, less intense swelling behavior is associated with predominantly tetrahedral charge deficiencies.

The composition of clay mineral suites derived from Triassic argillite and shale were compared with those of the consolidated parent sediments. Lockatong argillite, near the weathered zone, is composed mainly of illite, chlorite, and feldspar. In the clay horizon immediately above it, illite replaces the feldspar and kaolinite increases with distance from the contact until, near the top of the weathered zone, it is almost the only clay mineral present. A similar study was carried out on Brunswick shale. Here the parent rock consists mainly of illite, and some kaolinite, montmorrilonite, quartz, and feldspar. The kaolinite increases gradually as one progresses upward through the weathered zone, montmorillonite decreases, but approximately 30 per cent illite is still found in the top layers. Chlorite in the argillite near the weathered zone is randomly oriented while illite shows strong preferred orientation, probably indicating that chlorite formed in place during weathering. Illite in the Brunswick shale shows strong preferred orientation.

These two Triassic sediments are less than 5 miles apart and one may assume that they had a similar post-depositional environment. The difference in diagenetic development is striking and must be attributed mainly to the chemical composition and lithology of the parent sediment.

The orientation of clay particles in the solid rock was studied with the aid of an X-ray diffraction technique based on the analysis of cylindrical samples. Three-dimensional intensity data thus obtained were presented by vectors whose ends form a surface which is characteristic of the orientation of the particles. Generally the vectors generate hemispherical normal distributions whose principal vector coincides with the normal to the bedding plane.

Surface area determinations were made on a montmorillonite with various cations emplaced on the exchangeable sites, utilizing nitrogen and carbon dioxide as adsorbates at 77°K and 195°K, respectively, in a dynamic system. From the fraction of a Mississippi montmorillonite less than about 1 μ in size, samples were prepared by replacing the original exchangeable cations with Li+, Na+, K+, Rb+, Cs+, Mg++, Ca++, Ba++, and NH4+, forming a series of homoionic montmorillonite species.

Surface areas from 3-point B.E.T. plots (half-hour adsorption points), with nitrogen as the adsorbate, ranged from 61 m2/g for Li-montmorillonite to 138 m2/g for Cs-montmorillonite, thus reflecting a certain degree of nitrogen penetration between layers. Complete penetration should theoretically result in a surface area of over 300 m2/g for this clay with a nitrogen monolayer between each pair of platelets. The experimental data indicate that the extent of penetration is time-dependent and is also a function of the interlayer forces as governed by the size and charge of the replaceable cation. This finding negates the generally accepted concept that nitrogen at 77°K does not penetrate the layers and provides a measure only of the external surface of expandable clay minerals.

A further measure of the variation of interlayer forces is provided by the adsorption of carbon dioxide at 195°K. Surface area values ranged from 99 m2/g for Li-montmorillonite to 315 m2/g for Cs-montmorillonite. Although the carbon dioxide molecule is larger than the nitrogen molecule, its greater penetration apparently is a result of its being kinetically more energetic (with a larger diffusion coefficient) at its higher adsorption temperature. Similar differences have been found with both adsorbates in the study of microporous substances, such as coal, where activated diffusion is of considerable significance.

Electron microprobe studies of kaolinite indicate that most of the Fe is evenly distributed throughout the kaolinite and must either be in the structure or occur as very small particles adsorbed on the surface. In addition to Ti the anatase impurities contain Fe and Mg. Fe, Mg, Mn, V, and K are present in biotite. It is necessary to concentrate the fine-grained mineral impurities in order to study them with the electron microprobe.

The pyridinium-montmorillonite complex has the ability to sorb additional aromatic molecules between the layers. The neutral molecules occupy the vacant space produced by the change in orientation of the pyridinium ion from a parallel to a perpendicular position and with the N-H group directed toward the negative unit layer surface.

In favorable cases the orientation of the additional neutral molecules can be ascertained by infrared spectroscopy. Examples of this analysis are presented in the complexes of pyridinium-montmorillonite with chlorobenzene. The molecules adopt a vertical orientation but with the halogen bond axes parallel to the layers.

Seventy-four samples from eight stratigraphic sections of lower Pleistocene glacial and glaciofluvial deposits in Doniphan County, extreme northeastern Kansas, were analyzed using X-ray diffraction techniques. Clay-mineral) assemblages of the <2 μ fraction of these deposits are nearly identical, consisting of a mixed-layer clay mineral associated with minor amounts of kaolinite and illite.

An attempt was made to differentiate units of till and nontill deposits by using the relative intensities of 001 reflections of “mixed-layer mineral,” kaolinite, and illite. At least two tills were recognizable. Associated nontill deposits, could not be differentiated from one another, although the nontills are easily distinguished from tills.