Previous applications of the method of known additions for quantitative X-ray fluorescent analysis have assumed a linear relationship between peak intensity and concentration of the element being analyzed. This assumption is true for soils or sediments containing small amounts of the element in question. In this paper, an equation is derived which takes into account both absorption and enhancement and thus is applicable to samples containing high concentrations of the element. The equation was tested by analyzing an artificial soil sample containing 60% kaolinite and 40% hematite, i.e. the sample contained 28% by weight iron. The fluorescent analysis utilizing the equation derived here resulted in an iron content of 27%. In addition, nine soils from Hawaii were analyzed by this method and the results of these analyses compared with analyses by atomic absorption. The agreement between the two methods is good. It is concluded that the method and equations proposed here provides a reliable measurement of elements in a soil sample which contains high concentrations of the elements in question.

The effect of heat treatment on surface area, pore volume, pore size distribution, physical and chemical structure up to 700°C have been studied on samples of naturally occurring chrysotile minerals from California and Quebec. Techniques used included thermogravimetric analysis, low-temperature nitrogen adsorption, electron microscopy, X-ray powder and electron diffraction. The materials behaved similarly on heating to 100°C showing a 0.5% weight loss attributable to desorption of physisorbed water. At 500°C, Quebec samples retained the chrysotile crystal structure while Californian samples were X-ray amorphous. Forsterite was formed by dehydration of both chrysotiles at 700°C; the greater stability of the Quebec samples to this process is explained by the presence of brucite as an impurity which enters into stray solid-solid interactions with the chrysotile.

A series of chloro-alkylammonium montmorillonites was produced by cation exchange from Na+-montmorillonite. Gas chromatographic data were obtained for light hydrocarbons and certain oxides of nitrogen. Surface area and X-ray powder diffraction studies were made on each organo-clay, making possible differentiation between possible chromatographic pathways. Adsorption of the gas molecules on the silicate sheet was determined to be the dominant chromatographic pathway for all gases studied.

Mössbauer spectra of 15 smectites were investigated. In these samples, ferric iron occupies both M(1) and M(2) octahedral sites, the distribution being partly determined by the relative covalency of the bonds formed.

The quadrupole splittings are linearly related to b−3. They show that Fe3+ octahedra are much more distorted in montmorillonite and beidellite than in nontronite and volkonskoite and that M(1) sites are more prone to change than M(2). Ferrous iron occurs in relatively undistorted octahedra in some otherwise distorted octahedral sheets and vice versa.

Hydroxyl orientation has a major influence on the strength of the ionic interlayer bonding in micas because of the strong repulsion between the hydrogen and the interlayer cation (IC). In order to determine if other factors also influence the magnitude of the interlayer bond energy, the effect due to the varying H-IC distance, as one finds, for example, between a dioctahedral and a trioctahedral mica, must be removed. This can be done by calculating the bond energy as a function of the H-IC distance; a plot of which is a smooth curve with a minimum energy for the minimum H-IC distance. If there are no other factors which substantially contribute to the interlayer bonding energy, such curves for all micas should be superimposed. If, however, the curves are not superimposed but fall into groups with common attributes (stacking sequence, ionic substitutions, etc.) the energy separations between groups of curves indicate the influence of these other factors.

The results of such calculations for four dioctahedral micas (2M1 muscovite, 3T muscovite, and two 1M muscovites) and four trioctahedral micas (2M1 biotite, 1M phlogopite, 2M2 lepidolite and a 1M MgIV mica) indicate that these curves are at higher energy for dioctahedral than for trioctahedral micas and this energy increase is due to the filling of the octahedral sites. The dioctahedral micas are arranged in terms of energy as 1M ≥ 3T ≫ 2M1 while the order for the trioctahedral micas is 1M ≥ 2M1 ≅ 2M2. In addition, the calculated energies suggest that the distribution of the layer charge between the octahedral and tetrahedral sheets affects the strength of the interlayer bond such that the greater the charge on the octahedral sheet, the stronger the interlayer bond.

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.

The d(001) spacings for a series of montmorillonite samples containing increasing amounts of Cu(en)32+ were recorded after exposure to 50% humidity, 10% humidity, and air that had been saturated with ethylene glycol. It was found that Cu(en)32+ is too large to fit between the montmorillonite particles and that in those samples with large amounts of ethylenediamine Cu(II) added, the clay platelets are associated with stronger interactions than those with small amounts of Cu(II) complex added.

Infrared spectroscopy and electron spin resonance analysis indicate that the absorbed copper (II) complex is the square planar bis ethylenediamine Cu(II) and that the complex ion is oriented so that the $d_{z^2}$ orbital is perpendicular to the clay surface. The montmorillonite particles may act as ligands and coordinate with Cu(en)22+ ions.

An X-ray diffraction analysis of a barium-vermiculite shows it to have a triclinic unit cell with the following dimensions a = 5.33, b = 9.26, c = 12.47 Å, α = 100.75°, ß = 93.5° and γ = 90°. The proposed structure, adjusted in space group Cl, has the exchangeable cations approximately over the ditrigonal holes of the silicate surface and on either side of a hexagonal network of water molecules extending over the middle of the interlamellar region. The interlayer material imposes a relative displacement of ± b/4 on adjacent silicate sheets. The importance of these displacements, not previously found in layer silicates, is emphasized.

The dissolution of two relatively pure Australian palygorskites in mild acid was studied. For both palygorskites, Si and Mg releases were linear with respect to added acid. The rate of Si release with acid addition is equal to 0.66 μmol Si for each μmol H+ added in both palygorskites. The corresponding releases of Mg were 1.2 μmol for the Al-poor and 0.47 μmol for the Al-rich minerals. Mg appears to be preferentially released into solution over Si, and both Mg and Fe appear to be preferentially released into solution over Al, suggesting a lower stability of Mg and Fe-rich palygorskites compared to Al-rich varieties. The free energy of formation of one of the palygorskites was estimated as equal to −1143.7 kcal/mol.

Mössbauer characteristics of 57Fe nuclei in 8 samples of mineral glauconite of Cambrian age and one sample of Cretaceous age (slightly disordered) were obtained at temperatures between 50 and 295 K to evaluate the site occupation of iron in the octahedral sheet and the Fe3+/Fe2+ ratio. It was found that the resolution of Mössbauer spectra of glauconite is increased at low temperature.

The octahedral sheet in mineral glauconite is believed to contain two types of cationic environments with slight symmetry differences because of the position of oxygen and hydroxyl ions around the cation sites. One environment consists of two equivalent sites (M2), whereas the other is a single site (M1).

The Mössbauer spectra were fitted to a four-doublet model, two Fe3+ sites (M2 and M1) and two Fe2+ sites, and a three-doublet model, two Fe3+ sites (M2 and M1) and an average Fe2+ site. The former (four-doublet) model yielded lower χ2 and, also, line widths in close agreement with previous studies. However, since the Fe2+ concentration in the samples is low, the error in intensity of the Fe2+ occupation of the M1 and M2 sites leads us to conclude that Fe3+/Fe2+ ratios are more accurate for the three-doublet model.

Calculation of area ratios for the two Fe3+ doublets indicates that trivalent iron is strongly concentrated in the M2 site, which is smaller than the M1 site. Site preference of divalent iron could not be determined. The ratio of Fe3+/Fe2+ obtained from the Mössbauer spectra were usually within 8% of those obtained from chemical analyses.

X-ray mineralogical examination of the 2–20 μm fraction of oriented samples from a highly calcereous swamp soil and neighbouring Mio-Pliocene strata in Al-Hasa showed a wide range in mineralogy: attapulgite, illite, montmorillonite, chlorite and kaolinite, in decreasing order. Powder X-ray diffraction revealed an abundance of attapulgite, calcite, quartz and in a few samples, traces of dolomite, Fe-oxides, feldspars and gypsum.

The soils are believed to have been formed by deposition of highly calcareous wind-borne silt particles in an already formed swamp. The surface and subsurface horizons are underlain by an organic residue layer, 30–50 cm thick, containing 14–36% organic matter. The whole profile sits on hard, impervious, sedimentary layers that mineralogically resemble some strata of the outcrop.

Attapulgite and illite are the most abundant and common clay minerals in the soils and strata, but are most pronounced in the latter. Attapulgite not only occurs in Al-Hasa, but is widely distributed in the Arabian Peninsula; from east of the Mediterranean through the deserts of Syria and Iraq down to eastern Saudi Arabia, where it occurs only in association with limestone parent material. In this area of extreme aridity (Al-Hasa), the origin of the minerals and their relative abundance is believed to be associated with the source of sediment since minimum alteration seems to have taken place after deposition.

Nitrogen adsorption at 78°K and carbon dioxide sorption at 195°K on homoionic lithium, sodium, caesium, calcium, lanthanum and hexane diammonium saturated montmorillonites have been examined by means of V-n plots. In the case of carbon dioxide, sorption on the lithium saturated clay was used as a standard for comparison of the other samples.

The nitrogen plots indicate that most of the surface area lies in super-micropores of approximately 10 Å equivalent plate separation. Variations between cations are attributed to differences in the structure of the porous matrix formed on drying rather than differences in the degree of entry into quasi-crystalline regions. While the initial sorption of carbon dioxide clearly is influenced by the solvation properties of the cations, the subsequent reversibility of the isotherms and linearity of the V-n plots indicates that for all but the largest cations the same sorption process is occurring on surfaces external to the quasi-crystalline regions