bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple-Ion Diffusion—I. Techniques for Measuring and Calculating Apparent Self-Diffusion Coefficients in Heteroionic Systems
Authors: Brown D. A. , Dunn J. E. , Fuqua Ben 
Published: August 2006

AbstractThis investigation was designed to integrate the quick-freeze technique for ion diffusion with two computer programs to permit the simultaneous measurement and calculation of the diffus-ivity of a variable number of ions in heteroionic soil system. Kaolinite clay was prepared so as to have the following percentage saturations of the CEC, Sr2+65, Mg2+15, Rb+10, Na+5 and H+5. A quadruplicate radioisotope tag consisting of 85Sr, 28Mg, 86Rb, and 22Na was used to measure the diffusivity of each ion. The complex spectra were resolved by use of Schonfeld’s revised Alpha-M computer program. A probit-transformation procedure was formulated into a computer program to enable the calculation of each diffusion coefficient. These programs are described and illustrated with the diffusivity of 86Rb in kaolinite clay.
Chloritization of Montmorillonite by Its Coprecipitation with Magnesium Hydroxide
Authors: Gupta G. C. , Malik W. U. 
Published: August 2006

AbstractA magnesium hydroxide-montmorillonite complex prepared at an OH/Mg molar ratio of 2 (16 meq Mg/g clay) and immediately cleaned of any free Mg(OH)2 behaves like magnesium-chlorite and shows no change during 3 months ageing. Magnesium hydroxide completely precipitates within the interlayer space of montmorillonite. X-ray diffraction analysis, thermal (DTA and TGA) studies, i.r. absorption analysis, polarographic reduction behaviour, and cation exchange capacity measurements confirm the transformation of montmorillonite to a chlorite-like structure. Further ageing of the complex results in the release of brucite from the interlayer space and expansion of the complex on glycerol treatment. X-ray analysis of the 6 months aged sample shows the presence of free brucite but not montmorillonite. A small but significant increase in CEC of the complex is observed on ageing. When the Mg(OH)2-montmorillonite complex is allowed to age in the presence of free Mg(OH)2 (external to montmorillonite unit layers) in a dry state, a “seeding” effect takes place and the “fixed” Mg(OH)2 starts coming out from the interlayer space after 10 days.
Analogues of Flint Clays in Soviet Literature
Authors: Chukhrov F. V. 
Published: August 2006

AbstractThe term “flint clay” used in USA and several other countries, corresponds very closely to the term “toasted bread (sukhar) clay”. In both USA and U.S.S.R., the typical occurences of “toasted clays” are confined to deposits of the lower Carboniferous. In their properties and occurrence the well-studied toasted clays of the Borovichy deposit (Novgorod province) are highly similar to the flint clays of Missouri, differing significantly only in having lower bulk specific gravity and higher porosity than do Missouri flint clays. Varieties with excess free alumina (diaspore, boehmite) are observed both among “toasted” and flint clays. The author suggests the term “toasted complex” (sukharnii kompleks) which corresponds to W. D. Keller’s term “flint clay facies”. The clays of the “toasted complex” are sediments of ancient swamps and lakes which contained rich vegetation. Their source material was finaly dispersed silicate particles transported from dry land. The structure and properties of toasted clays are explained by the precipitation of kaolinite as colloidal clumps in which crystallization occurred with formation of intimate intergrowths and variously oriented segregations.
Potassium and Cesium Ion Selectivity in Relation to Clay Mineral Structure
Authors: Sawhney B. L. 
Published: August 2006

AbstractSelectivity of a number of vermiculites, montmorillonites and micas for K and Cs ions was determined by sorption of these ions from equilibrium solutions of diverse concentrations. The selectivity coefficients were related to the layer charge density and the area of the frayed edges in layer silicates.Montmorillonites had the smallest selectivity for the two ions, while biotite and illite had the greatest selectivity. Selectivity of biotite and illite was limited to small concentrations of K, however. At greater concentrations the selectivity of vermiculite for K exceeded the selectivity of the micas.The greater selectivity of vermiculites than montmorillonites for K and Cs ions was attributed to the greater layer charge density in vermiculites. The greater selectivity of micas than montmorillonites and vermiculites was attributed to the frayed edges of micas in addition to their larger layer charge density. As the frayed edges in illite were increased in area by removal of the interlayer K, the selectivity of illite for K also increased; thus confirming the selectivity of frayed edges for the K ions.
Titanium as Free Oxide and Substituted Forms in Kaolinites and other Soil Minerals
Authors: Dolcater D. L. , Syers J. K. , Jackson M. L. 
Published: August 2006

AbstractTitanium in TiO2 minerals was differentiated from that isomorphously substituted into minerals by the use of dihydrogen hexafluorotitanate (hydrofluotitanic acid, H2TiF6), which selectively dissolved minerals containing substituted Ti4+, leaving free crystalline TiO2 minerals in the residue. Titanium analyses on the original samples and the residues remaining after H2TiF6 treatment, by both wet chemical (Tiron) and neutron activation methods, indicated that an average of 86 per cent of the titanium in seven kaolinite samples was present in the residual TiO2 form (largely anatase), whereas only 28 per cent in two bentonites was present in the TiO2 form. Residual Ti accounted for 100 per cent of the Ti in synthetic anatase and for 92 per cent of the Ti in coarse clay sized rutile, the latter value suggesting that about 8 per cent amorphous TiO2 was removed from the mechanically dry ground rutile by the H2TiF6 reagent. The Ti present as residual TiO2 in a variety of other samples ranged from 0 to 100 per cent.
pH Dependent Ion Exchange Properties of Soils and Clays from Mazama Pumice
Authors: Chichester F. W. , Harward M. E. , Youngberg C. T. 
Published: August 2006

AbstractCation exchange capacity (CEC) measurements were made for whole pumice soil samples by several methods, including standard procedures involving cation saturation, excess salt removal, and cation displacement steps, and a 45Ca2+ radioisotope dilution procedure. Results indicated that the vesicular pores of the pumice soil material affected attainment of ion diffusion equilibria, and, hence, introduced a large source of error in the measurements. On this basis, the validity of ion exchange values obtained for these soils was concluded to be subject to considerable doubt. More important, however, the solute and/or solution exclusion or retention exhibited by pumice particles during the course of CEC procedures was thought to be highly significant with respect to the probable influence exerted on physical, chemical, and biological properties of the soils in the field situation.Interpretation of pH dependent cation and anion exchange capacity measurements of the <2μ clay fraction of the pumice soils was confounded by the occurrence of hydroxy interlayered 2: 1 phyllosilicate materials in admixture with the amorphous components. Since the interlayered materials contributed an indeterminate proportion of the total pH dependent charge of the mixture, it was further concluded that the measurement of this property was of little direct value in assessing the relative amounts of amorphous and crystalline components in the clay fractions of the soils investigated. However, the values obtained revealed fundamental aspects of ion exchange behavior which are important to understanding the complex systems involved.
Adsorption of Surfactants on Montmorillonite
Authors: Hower Wayne F. 
Published: August 2006

AbstractSome authors have stated that anionic surfactants are not adsorbed by montmorillonite while others indicate very minor adsorption. Attempts to quantitatively determine the degree of adsorption have shown that certain problems exist which, unless recognized, will completely mask results. Some of these difficulties have been overcome but exact data have not yet been obtained. However, enough information has been gathered to prove that adsorption of anionic surfactants on montmorillonite is real and substantial. Reliable adsorption data for cationic and nonionic surfactants and one having both nonionic and anionic character have been obtained. It is indicated that 550 mg of these surfactants are adsorbed by 1 g of montmorillonite. X-ray diffraction data for complexes of all surfactants investigated confirm positive adsorption. However, the thickness of the adsorbed surfactant layers cannot always be quantitatively related to the amount of adsorbed surfactant.
Rectorite and the Rectorite-Like Layer Structures
Authors: Henderson G. V. , Bradley W. F. 
Published: August 2006

AbstractRecurrent reports of analyses of X-ray diffraction data from regularly alternating and nearly regularly alternating structures like rectorite provide opportunity for a descriptive discussion of their nature. MacEwan-transform-based analyses have uniformly shown higher incidence of unlike adjacent layers than would be expected from random distribution.The continuous Fourier transforms for pairs of 2: 1 layer silicate structures evaluated normal to the layers, provide a family of similar curves that are differently stretched out in reciprocal space for different assumed intervals between the two members of a pair.For each exactly alternating example the relative amplitudes of the ordered reciprocal nodes distinguish the instances for which fixed interlayer populations are Na+ from those for which they are K+.For sequences not exactly alternating scattering maxima are displaced from exact incremental positions in conformity with the Hendricks and Teller mixing functions, but relative intensities of adjacent observations still distinguish the alkali identities.
Burial Diagenesis in Gulf Coast Pelitic Sediments
Authors: Perry Ed , Hower John 
Published: August 2006

AbstractSubsurface samples of shales ranging in age from Pleistocene to Eocene obtained from five Gulf Coast oil wells were examined mineralogically and chemically to determine the nature and extent of burial diagenesis in pelitic sediments. Illite/montmorillonite dominates the mineralogy and undergoes a monotonic decrease in expandability from about 80 to a limit of 20 per cent montmorillonite layers with increasing depth. The interstratification changes from random to ordered at about 35 per cent expanded layers. Discrete illite and kaolinite phases are ubiquitous and judged detrital. The discrete illite (mica) content of the whole rock decreases with depth, while the kaolinite shows no systematic variation. Chlorite occurs in appreciable amounts in only one well and there only in samples from the shallow water facies. This chlorite is also considered detrital.Whole rock chemical analyses show no systematic variation with depth except for a decrease in calcium and magnesium caused by solution of carbonate. In contrast, potassium increases progressively with depth in the clay-size fraction, indicating a redistribution of potassium within the rock. Detrital illite (mica) seems to break down with increasing depth, thereby supplying potassium for interlayer fixation in illite/montmorillonite as the proportion of illite layers increases. The diagenetic reaction is independent of the geologic age of the sediments and of stratigraphic boundaries. Temperature seems to be more important than pressure in governing the reaction.
Effects of Potassium Removal on the b-Dimension of Phlogopite
Authors: Leonard R. A. , Weed S. B. 
Published: August 2006

AbstractPotassium was removed from 5 to 20-μ size fractions of two phlogopites by treatment with sodium tetraphenylboron and replaced with various exchange ions. The b-dimension of the mica increased with K+ removal, which suggests that the K+ ion in phlogopite acts to constrain b. This being the case, the K—O bond in phlogopite must be lengthened and weakened relative to the K—O bond in dioctahedral micas.
The Origin of Pyrophyllite Rectorite in Shales of North Central Utah
Authors: Henderson G. V. 
Published: August 2006

AbstractPyrophyllite is widespread in pelitic rocks of the Manning Canyon Shale in north central Utah, and the association of this mineral with other clay minerals, especially rectorite is related to the origin. The regular mixed-layer clay mineral rectorite seems to form as a result of the alteration of muscovite-paragonite during late stages of diagenesis and represents an intermediate metastable phase in the mineral paragenetic sequence. Pyrophyllite subsequently formed from the alteration of rectorite during advancing metamorphism and is the stable end member of the clay mineral assemblage.Structural interpretations of rectorite found in the Manning Canyon Shale shows a regular, alternating sequence which consists of a fixed layer of 9.6 Å and an expandable layer, varying from 10 Å to 17 Å. With ethylene glycol saturation in the natural state a basal reflection of 26.60 Å is recorded.
Precipitation of Kaolinite at 25°C and 1 ATM
Authors: Kittrick J. A. 
Published: August 2006

AbstractThe 0.2–5μ particle size fraction of montmorillonite from three sources was equilibrated with various solutions at room temperature. After 3–4 yr, kaolinite was found in some of the samples that were supersaturated with respect to kaolinite, but not in any of the undersaturated samples or in the original montmorillonite. X-ray diffraction analysis of the precipitated kaolinite showed no inter-layer expansion of glycerated, oriented samples. Random powder samples indicated a poor crystal-Unity. The thermal stability of the precipitated material was indistinguishable from that of crystalline kaolinite. The electron microscope did not reveal any distinctive sizes or shapes.Equilibration behavior of several samples defined a single kaolinite solubility line at or above which kaolinite apparently begins to precipitate. The solubility line is equivalent to a standard free energy of formation (ΔG) of -904.2 kcal per mole of kaolinite. This represents highly crystalline kaolinite. The stability of kaolinite actually precipitated at room temperature probably depends upon precipitation conditions. Thus kaolinite stability could range from poorly crystalline up to the equivalent of the kaolinite solubility line at which initial precipitation begins.
Polytypism of Chlorite in Sedimentary Rocks
Authors: Hayes John B. 
Published: August 2006

AbstractFour chlorite polytypes of Bailey and Brown (1962) have been identified by X-ray diffraction in clay-size chlorites of soils, sediments, and sedimentary rocks: (1) IIb, the polytype of common metamorphic and igneous chlorites; (2) Ib(ß = 90°); (3) Ib(ß = 97°); (4) Ia. An additional stacking arrangement. Iba, is defined herein as disordered chlorite which lacks an h0l diffraction band in the 2.4–2.5 Å region.Most type-I chlorites are authigenic, as demonstrated by thin-section petrography. Type-I chlorites form during diagenesis, or less commonly during halmyrolysis, at temperatures and pressures less than those of low-grade metamorphism. A type-1 crystallization sequence is proposed, from least to most stable: Iba → Ib(ß = 97°) → Ib(ß = 90°). Conditions of low-grade metamorphism usually are necessary to cause conversion of Iba(ß = 90°) to IIb, the most stable and common polytype. Chemical composition has little or no influence upon polytype relative stabilities; temperature is much more important.Sediment source areas with high relief, abundant rainfall, cold climate, and which contain IIb-chlorite-bearing metamorphic rocks, may yield essentially unweathered IIb chlorite to sites of deposition. Thus, clay-size IIb chlorite in unmetamorphosed sedimentary rocks can be interpreted as detrital. Caution is required, however, because IIb may be able to form authigenically at submetamor-phic temperatures, because it is the most stable polytype. Petrographic evidence is useful in such cases.Chlorite polytypism as a geothermometer can be applied to several geologic problems: (1) the authigenic versus detrital origin of clay minerals in sedimentary rocks, particularly in graywacke matrix; (2) the recognition of diagenetic facies or gradients, areally and stratigraphically, within given geologic provinces; (3) the detection of hydrothermal and incipient metamorphic effects. Chlorite polytypism merits general application as an interpretive tool.
Globular Cluster Microstructure of Endellite (Hydrated Halloysite) from Bedford, Indiana
Authors: Diamond Sidney , Bloor James W. 
Published: August 2006

AbstractScanning electron microscope observation of endellite from Bedford, Indiana, discloses the existence of globular clusters of quasi-tubular endellite particles radiating from common centers. Individual clusters are of the order of 10 μ in overall diameter. The individual quasi-tubular particles are irregularly flattened in cross section, and some may be plugged at the ends. Conventional oven drying at 105°C results in partial unrolling and incomplete flattening of the quasi-tubular particles of some of the clusters. The globular cluster microstructure is taken to represent the result of in-situ crystallization from solution. If this is so, these hollow tubes cannot have arisen by the mechanism of repeated extrusion of concentric zonal crystallites as postulated by Chukhrov and Zvyagin.
Prototropy in Kaolinite during Percussive Grinding
Authors: Miller John G. , Oulton T. Dixon 
Published: August 2006

AbstractWhen kaolinite undergoes percussive grinding, pronounced changes take place in its i.r. absorption spectrum even in the earliest stages of the grinding when the lattice is not yet destroyed. In this report, attention is directed to the change in the stretching bands of the hydroxyl ions. A remarkably rapid effect on the band of the intralayer hydroxyl ions has been observed and is attributed to a permanent removal of the protons from these ions. Auxiliary measurements of X-ray diffraction, thermal water loss, and DTA were used to corroborate the spectroscopic evidence for this ready prototropy.
Ion Selectivity by Weathered Micas as Determined by Electron Microprobe Analysis
Authors: le Roux J. , Rich C. I. , Ribbe P. H. 
Published: August 2006

AbstractElectron probe micro-analysis studies on individual particles (40–60 mesh) of weathered micas treated with solutions containing equivalent amounts of Rb and Sr showed partial segregation of these elements. Rb was concentrated at particle and step edges, at cracks, and, in the case of partially K-depleted biotite, at boundaries of vermiculite and mica zones (“wedge zones”). The scarcity of wedge zones in mica from which nearly all of the K had been removed reduced the overall selectivity for Rb. The restricted exchange of interlayer Mg ions from vermiculite-like zones by a mixed Rb-Sr solution was observed in earlier studies with these micas. The proposed explanation for these results was a closing down of the interlayer space at the edge of the particle due to Rb concentration in these positions. This explanation is confirmed by the present study.
The Nature of Clay Soils from the Mekong Delta, An Giang Province, South Vietnam
Authors: Post James L. , Sloane Richard L. 
Published: August 2006

AbstractSoil samples from near Long Xuyen, South Vietnam, considered to be typical of the clayey alluvial soils of the Mekong Delta, were investigated to determine the soil mineral content and soil type. The soils are of fairly uniform composition, consisting mainly of clay minerals and quartz. the predominant clay minerals including illite and chlorite with lesser amounts of kaolinite and smectite. The small hydrous iron oxide content, indicated by fluorescence background intensity, verified that the soils are not latosols but are clayey estuarine soils amenable to future development as arable land.The method of specimen preparation enabled direct quantitative analysis of the soil samples by X-ray diffraction with the aid of the results of mechanical analysis and of previous analyses of comparable soil samples from the Delta and nearby areas. A method for the quantitative determination of quartz was used that is independent of the powder crystallite orientation. A study of surface replicas of the soil samples by electron microscopy was made to illustrate the fabric of the soil. The undisturbed soil fabric consists mostly of somewhat randomly-oriented large domains of clay minerals with some blocky quartz particles. Nanno-fossils were present in all samples.
Optical and Electron Microscopic Investigation of Shear Induced Structures in Lightly Consolidated (Soft) and Heavily Consolidated (Hard) Kaolinite
Authors: Foster R. H. , De P. K. 
Published: August 2006

AbstractA review of fabric studies of clays suggests the need for relating those fabric characteristics which are revealed at the two levels of magnification provided by optical and electron microscopy, and a technique to achieve this has been developed and is described within the context of the initial stages of a long term study of the interrelation between fabric and engineering behaviour. Two kaolinitic clays with contrived fabrics were prepared by controlling particle size, moisture content and pH of suspension, and consolidation load and were subjected to shear loading to failure. Resin impregnation techniques which permit the kaolinite to be cut into thin sections for transmission electron microscopy have been optimized with the object of minimizing fabric strain and damage during ultratomy.The fabrics of the hard and soft ambient material are qualitatively compared by means of electron micrographs and are explained in terms of the preparatory procedures adopted for fabric control. The fabrics of the two types of shear induced structures are also qualitatively compared and explained in terms of the original fabrics and the subsequent shear loading.
Scanning Electron Microscopy of Clays and Clay Minerals
Authors: Bohor B. F. , Hughes Randall E. 
Published: August 2006

AbstractThe scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units — interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis — also are uniquely revealed by the SEM.Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types.
I.R. Spectroscopic Evidence for Interaction Between Hydronium ions and Lattice OH Groups in Montmorillonite
Authors: Russell J. D. , Fraser A. R. 
Published: August 2006

AbstractAt low levels of hydration, exchangeable D+ in montmorillonite interacts with lattice OH groups and quantitatively converts AlMgOH groups to AlMgOD. Hydroxyl groups coordinated to two Al ions undergo a slower exchange, the extent of which is restricted by octahedral Fe3+ ions. The OH stretching vibration of AlMgOH groups in montmorillonite is assigned an unusually high frequency (3687 cm−1) compared with that of the same group in phengites (3602 cm−1).