bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of Stabilization of Cohesive Soils by Treatment with Organic Cations
Authors: Davidson D. T. , Demirel T. , Rosauer E. A. 
Published: August 2006

AbstractThe amount of moisture in a soil and its orientation to individual soil particles may be influenced by small additions of organic cationic compounds. Clay particles adsorb these cations, and because of their hydrophobic nature a waterproofing effect occurs. Thermodynamic considerations are presented to explain the strength retention of treated soils.
Formation of Dioctahedral Vermiculite in Virginia Soils
Authors: Rich C. I. , Cook M. G. 
Published: August 2006

AbstractThe weathering of micas to form the dioctahedral analogue of vermiculite is a common process in acid soils. Laboratory weathering of the micaceous 5–2μ fraction of parent materials of certain Virginia soils resulted in a product similar in character (whether mixtures of vermiculite and regularly and randomly interstratified mica—vermiculite, or vermiculite only) to those formed by natural weathering processes. The formation of vermiculite rather than (or, in addition to) kaolinite is attributed to substitution of Na and other ions for K, other structural imperfections, and the small size of the original mica flakes.The low cation exchange capacity and stability, in contraction and expansion, of the 14Å product is attributed partly to retention of hydroxy-Al and Fe groups in the interlayer spaces. The removal of these interlayers by natural or laboratory processes results in a product that contracts easily but may or may not expand to 18 Å on glycerol solvation. This may be associated with the original charge of the mica as evidenced by its K and Na content.
A Glycol—Sodium Vermiculite Complex
Authors: Bradley W. F. , Weiss E. J. , Rowland R. A. 
Published: August 2006

AbstractA complex of vermiculite with ethylene glycol was prepared by repeated boiling of a sodium-saturated cleavage flake in dry ethylene glycol. A stable product with a c period of 12.9 Å afforded 15 terms for a one-dimensional Fourier synthesis. A model composed of glycol molecules with the plane of the zigzag normal to the silicate face is found to be consistent with the observed diffraction data. The complex apparently conforms to a stoichiometric ratio of two molecules per unit cell per layer of vermiculite.
Organic Cation Exchange on Montmorillonite as Observed by Ultraviolet Analysis
Authors: McAtee James L. 
Published: August 2006

AbstractAn analytical method is described whereby the exchange of various organic cations for other organic cations on montmorillonite is determined. The exchange is followed by means of a Beckman DK-1 ultraviolet spectrometer.It has been observed that organic cations from compounds such as primary, secondary, and tertiary amine salts and quaternary ammonium salts can be exchanged for one another on the natural cation exchange substance, montmorillonite. The exchange is carried out in isooctane to which a small amount of isopropyl alcohol has been added to aid in dispersion of the organic-clay complex. By choosing pairs of organic substances, of which one has strong absorbance in the ultraviolet and the other does not, the exchange can be followed quantitatively with the u.v. spectrometer.
An Improved Pretreatment for Mineralogical analysis of Samples Containing Organic Matter
Authors: Anderson J. U. 
Published: August 2006

AbstractOrganic matter removal is accomplished rapidly and efficiently without removing carbonates by treating samples with a sodium hypochlorite solution. Quantities of organic matter left in samples by this treatment are commonly less than remain after hydrogen peroxide treatment of acidified samples.Stable suspensions result from the use of a sodium carbonate-sodium bicarbonate solution to wash and sodium saturate the samples without dissolving or complexing sesquioxides.
Cesium Sorption Reactions as Indicator of Clay Mineral Structures
Authors: Tamura Tsuneo 
Published: August 2006

AbstractAt low cesium ion concentrations extremely high selectivities for cesium are exhibited by layer lattice silicates with unexpanded 10 Å c-spacing. The total amount of cesium which can be sorbed by these minerals depends on the edge area and the exchange capacity. At a concentration of 10−5 meq of cesium and 5 meq of sodium, a sample of biotite representing less than 0.025 meq of exchange capacity sorbed over 90 per cent of the cesium and a hydrobiotite with 50 percent vermiculite and representing 1.0 meq of exchange capacity sorbed 80 percent of the cesium.After heating bentonites to 500–700° C more cesium is sorbed from solutions containing high sodium concentrations by the heated bentonite than the original material. The change in the amount of cesium sorbed as a result of heating may be a useful property for detecting the presence of montmorillonite in mixed or interlayered mineral systems. Lattice expansion of biotite results in improved cesium sorption; this behavior is due to generation of sufficient favorable exchange sites to offset the loss of edges with favorable 10 Å spacing.
Clay Mineralogy of Mississippian Strata of Southeast Iowa
Authors: Hayes John B. 
Published: August 2006

AbstractClay mineral suites were extracted from 125 biocalcarenites, dolomites, mudstones and arenaceous rocks from the marine Keokuk, Warsaw and Salem formations of Mississippian age from southeast Iowa and nearby portions of Illinois and Missouri. Well crystallized illite, 2M1 polytype, randomly interstratified illite—montmorillonite, and quartz are in all clay suites. In the south part of the area, trioctahedral chlorite is absent or rare in Keokuk rocks, but is increasingly abundant upward in the section. Kaolinite is confined to the upper part of the section. In the north part of the area, the same upward order of appearance prevails, but the first appearances of chlorite and kaolinite are shifted downward in the stratigraphic section. This distribution of clay minerals is similar to that found by investigators in other areas: kaolinite confined near shore, chlorite in an intermediate position and illite concentrated farther from shore. Clay mineral evidence, combined with petrographic and stratigraphic data, strongly indicates that the type Mississippian strata of southeast Iowa were deposited in a southward regressing epicontinental sea.Vermiculite and abundant mixed-layer illite-montmorillonite, weathering products of chlorite and illite, respectively, mark a local unconformity between lower and upper members of the Warsaw Formation on the crest of the Warsaw Anticline.
Experiments on the Decomposition of Silicates and Discussion of Chemical Weathering
Authors: Correns Carl W. 
Published: August 2006

AbstractExperimental investigations of chemical weathering in which powders of potassium feldspar, albite, leucite, muscovite, tremolite, olivine, and volcanic glass are treated with pure water and with dilute solutions of sulfuric, carbonic, and hydrochloric acid have been performed in an apparatus in which the mineral powder is exposed to a circulating water flow. The experiments have been continued recently by treating kaolinite and montmorillonite. The course of decomposition of these minerals depends on water flow rate, grain size, temperature, and pH of the solutions. These experiments in open systems are compared with investigations reported in the literature and with the conditions of natural weathering.
Bentonite-Methylamlne Complexes
Authors: Rowland Richards A. , Weiss E. Joseph 
Published: August 2006

AbstractSuspensions containing 3 percent sodium bentonite (Wyoming) and each of the four methylamine hydrochlorides were prepared so that the latter were present in amounts equal to 25, 50, 75, 100, 125, 200, 400, 600, 800, and 1000 percent of the exchange capacity of the clay. The flocculated clay was removed by decantation, and an oscillating -heating X-ray diffraction (Cu Kα.) pattern was made of the first-order diffraction maximum. With these patterns, the thermal stability, mixed layering, and multilayering of the amine-bentonite complex were followed. For methylamine, the data suggest that the first cations to enter lie in the holes with their C-N axes as close to the oxygen surface as possible. As additional methylamine hydrochloride enters, the C−N axis stands perpendicular in the holes to accommodate the chloride, and after all the holes are filled a second layer forms. Although the geometry of the dimethylamine cation permits it to occupy only two out of three holes, it also forms a second layer. The trimethylamine and tetramethyl ammonium cations are so large that they can occupy only one hole in three; this distribution satisfies the cation-exchange capacity, but a second layer does not form.
Nonmontmorillonitic Composition of Some Bentonite Beds
Authors: Schultz L. G. 
Published: August 2006

AbstractAlthough the wide range of minerals resulting from alteration of tuffaceous rocks under hydrothermal and weathering conditions is well known, the extent of variation in composition of discrete bentonite beds subjected only to normal diagenesis and compaction is perhaps less well known.Three bentonite samples from the Atoka Formation of Pennsylvanian age are predominantly mixed-layer illite-montmorillonite with subordinate kaolinite. Most bentonites in the Fierre Shale of Late Cretaceous age are entirely montmorillonite, but a few contain some kaolinite; one is predominantly kaolinite; some also contain appreciable interlayer Al(OH)3 or Mg(OH)2 forming a mixed-layer montmorillonite-chlorite clay; several are composed of considerable clinoptilolite, and one is largely phillipsite. Bentonite beds in the Carmel Formation of Middle and Late Jurassic age differ among themselves in composition; in a few, illite is the dominant clay; in others, mixed-layer chlorite-montmorillonite-illite in different proportions is the dominant clay; kaolinite is common and makes up nearly half of one sample. A rhyolite tuff near Denver, Colorado, has been altered to halloysite. Reasons for variation in the composition of these bentonites are only partly understood.
Compaction of Clay Sediments in the Range of Molecular Particle Distances
Authors: van Olphen H. 
Published: August 2006

AbstractThe physical process of compaction of clay sediments and the inverse process of swelling can be discussed in terms of particle interaction forces. The swelling pressure in a given situation equals the nct repulsive force per unit area between the particles. The net repulsive force is the resultant of various repulsive and attractive forces. Two stages of swelling or compaction can be distinguished, one in which the particles are relatively far apart, and a second in which they arc separated by only a few monomolecular layers of water.In the first stage the swelling pressure is primarily due to double-layer repulsion (“osmotic swelling”). The pressures range from a fraction of one atmosphere to several times ten atmospheres. These pressures are of particular interest for foundation engineering problems.In the second stage the swelling pressures are dominated by the work of adsorption of the water layers on the clay surfaces. Tile pressures may reach several thousand atmospheres. Quantitative data on the swelling pressures in this range are derived from water vapor sorption isotherms combined with X-ray data on the c-spacing of expanding clays during dehydration.It is concluded that overburden pressures in nature will seldom be high enough to remove all adsorbed water from between parallel grain surfaces.
Mineralogy of Ordovician K-Bentonites in Kentucky
Authors: Huff Warren D. 
Published: August 2006

AbstractPreliminary results of investigations of Trenton-Black River (Ordovician) K-bentonites from well cores in northern Kentucky and from outcrops along the Kentucky River illustrate the variations in some physical and chemical properties. It is hoped that some features may eventually be useful in stratigraphic correlation, considering that the very nature of these altered ash beds makes them ideal time-lines.That these beds are derived from volcanic ash is evidenced by significant amounts of biotite, magnetite, leucoxene, apatite, and zircon.The following means of investigation have been employed: X-ray diffraction, DTA, cation exchange, heavy mineral studies, and insoluble residue studies of adjacent limestones. X-ray analyses of untreated and glycolated clay samples indicate a mixed-layer, dioctahedral, illite-montmorillonite type structure with an I-M ratio varying from 4:1 to 3:2. The proportion of expandable layers in many samples is higher than that reported for Ordovician K-bentonites elsewhere. No evidence of chlorite is detected.DTA data show a primary hydroxyl peak near 725°C suggesting a basic montmorillonite-type of hydroxyl bonding. Treatment with 1M solutions of various cations produces a slight expansion of the expandable layers with Ca2+, and contraction with Na+, K+, and NH4+ giving some indication of original environmental composition. The evidence supports suggestions by earlier authors that the clays are basically montmorillonites which have undergone partial contraction due to the adsorption of potassium in the interlayer positions.While euhedral zircons are most likely non-detrital, recent work on zircons in igneous rocks suggests the same may also be true for some of the sub-rounded and fractured species.Insoluble residues of limestones contain abundant chert and mixed-layer illite-montmorillonite clay directly adjacent to the ash beds, but farther away illite and chlorite dominate and are probably detrital in origin.
Clay Formation and Accumulation in Selected Oklahoma Soils
Authors: Gray Fenton , Reed L. W. , Molthan H. D. 
Published: August 2006

AbstractThe clay minerals were studied from eleven soil profiles representing three Great Groups of eastern and central Oklahoma. Montmorillonite and illite type clay minerals were found to be the dominant minerals; montmorillonite dominates the fine clays; illite is the chief constituent of the coarse clays. The fine clays dominated the clay fraction of most horizons, including the parent material. The results of the investigation indicate that the present régime of soil formation has had little effect in altering the clay minerals of the soil from those present in the original sediments.
Identification of Kaolin Minerals in the Presence of Chlorite by X-Ray Diffraction and Infrared Absorption Spectra
Authors: Kodama Hideomi , Oinuma Kaoru 
Published: August 2006

AbstractExperimental data are presented to show that the current auxilliary procedures adopted for identification of kaolinite in the presence of chlorite are not generally valid because the procedures often fail to give an explicit condition for distinguishing both the minerals.As the result of an examination of numerous infrared spectra in the OH region of clay minerals, obtained by using Nippon Bunko DS-401G Grating Speetrophotometer, it turned out that the absorption band at 3698±2 cm−1 is effective for distinguishing kaolinite from other clay minerals without the use of any additional techniques. The absorption band seems to be less affected by variation of particle size and crystallinity than is the X-ray diffraction pattern. The band is detectable to a few weight percent of kaolinite in total amounts of clay minerals. Identification of kaolinite by its absorption spectrum in clay samples from sedimentary rocks was successful.
Mechanism of NH3 Adsorption by Montmorillonite and Kaolinite
Authors: James D. W. , Harward M. E. 
Published: August 2006

AbstractDry, homoionic systems of two montmorillonites and a kaolinite were treated with NH3 and then evacuated exhaustively to eliminate any physically adsorbed ammonia. It was concluded that the NH3 retained by the minerals was associated with the exchangeable cations. The mechanism of this adsorption process is the same as that which leads to the formation of inorganic ammines, namely, the mutual attraction between unshared electrons in the NH3 molecules and ionic centers of positive charge. This sorption process is reversible at elevated temperatures and is described by the equation, nNH3 + CX ⇄ (nNH3 · C)X, where n is the number of NH3 molecules associated with each exchangeable cation, C, on exchange complex X. Accordingly, n is a coordination number and has the following values for the cations indicated: NH4, 0; K, 0; H, 1; Ca, 2; Mg, 2; Alin, 3; Alex, 6. Here in and ex refer to interior and exterior exchange sites respectively. The retention of NH3 by cations which saturate the exchange complex of clays was shown to be analogous to the formation of ammoniates by reaction of NH3 with inorganic salts.A reduced retention of NH3 by the Mg and Al 1:1 systems was ascribed to the possibility that exchangeable Mg and Al on kaolinite occur as hydroxy complexes.A significant amount of NH3 was adsorbed to the weak acid hydroxyl groups on the broken clay edges, Relative to exchange capacities this phenomenon was greater in magnitude on the 1:1 than on the 2:1 clays.Energies of NH3 adsorption on CaCl2, Ca-bentonite and NH4-bentonite were determined. Values of △H as a function of temperature were shown to be different for the Ca and NH4-clay systems. The data indicated stronger energies of retention of NH3 by the Ca-clay than for the NH4 clay. The thermodynamic data thus support the mechanisms proposed here.
Crystallographic Aspects of High Temperature Transformations of Clay Minerals
Authors: Taylor H. F. W. 
Published: August 2006

AbstractThis paper deals with the dehydroxylation reactions of clay minerals and allied substances such as lamellar hydroxides, serpentine minerals, and amphiboles. Probably in all cases, these reactions occur topotaxially, that is, there is a three-dimensional similarity between the crystal structures of starting material and product, as a result of which each crystal of the starting material is changed into something approaching a single crystal of the product. Many investigators have studied the orientation relationships between starting materials and products, and their results have provided the main experimental foundation for hypotheses about the reaction mechanisms. These hypotheses have, however, rested also on assumptions, of which until recently three have usually been made. These are (i) loss of water occurs more or less uniformly from all parts of the crystal; (ii) the Si-O parts of the structure are more stable than the metal-oxygen parts; and (iii) the silica-rich material often presumed to be formed as a subsidiary product is pure SiO2. Recent work suggests, however, that none of these assumptions is securely based, and the purpose of this paper is to suggest an alternative approach to the problem.The high temperature reactions of clay minerals are perhaps best understood by treating the latter as assemblies of close packed, or nearly close packed, oxygen ions with cations in the interstices. From this point of view, one might expect that the relatively small cations, such as Si4+, Al3+, Mg2+, and especially H+ would move more easily than the oxide ions. One would not expect the oxygen atoms that are lost as water to be necessarily those present initially as OH- groups; they are more likely to be those that can most easily escape from the structure, e.g. from near external surfaces or grain boundaries. On this hypothesis, a typical dehydroxylation reaction involves three types of process:Loss of oxide ions from exposed or “donor” regions, and their combination with H+ ions from all regions, to form water. The donor regions are changed into pores.Cation migrations. These may be of two kinds. Firstly, all cations other than H+ migrate from the donor regions into the remaining or “acceptor” regions, and H+ ions migrate in the opposite direction. Secondly, within the acceptor regions themselves, further migrations may cause differentiation into Si-rich and Si-poor parts to occur.Changes in the type of oxygen packing in the acceptor regions, to complete the formation of the crystalline products. These last changes may occur throughout the acceptor regions, or only in certain parts of them.
Electrical Resistance Measurements of Kaolinite and Serpentine Powders During Dehydroxylation
Authors: Nakahira M. 
Published: August 2006

AbstractDirect current resistance measurements were made of kaolinite and serpentine powders to follow the changes in resistances during their dehydroxylation processes in air. The resistance of kaolinite remained almost constant during the dehydroxylation, whereas that of serpentine showed a rapid decrease. The formation of distorted lattice sites where the charge carriers are scattered under an electric field was assumed in the former case. On the other hand, the result in the latter case was interpreted in terms of an increasing cation mobility.
Kinetics of the Thermal Dehydration of Hydrous Silicates
Authors: Holt J. Birch , Cutler Ivan B. , Wadsworth Milton E. 
Published: August 2006

AbstractGenerally, the rate of dehydroxylation of clay minerals may be controlled by reaction at the interface between the decomposed and undecomposed mineral, diffusion through the decomposed phase and/or nucleation of the decomposed phase. Only in rare instances are mineral decomposition reactions homogenous. Some examples are presented to illustrate these principles.For macrocrystalline muscovite the initial sample weight rather than the external surface area was found to be a parameter of the rate of weight loss. Upon grinding the muscovite to particles smaller than — 65 mesh, an internal surface area factor strongly influenced the rate. This surface area was related to dislocations shown to be present in muscovite.A rate equation is presented that explains the observed weight loss versus logarithm of time dependence based on a model involving a systematic relief of strain during dehydration.The rate equation for pyrophyllite was exactly the same as that formulated for muscovite. As with muscovite there was a change in free energy of activation throughout the dehydration process. In contradiction to muscovite, the contribution to the free energy of activation was at least partly enthalpy while with muscovite it was an entropy of activation contribution.The dehydration of kaolinite was carried out in vacuum. At pressures of one micron the reaction was found to be diffusion controlled with hydroxyl ions as the likely diffusing species.
Studies on the Properties and Formation of Quick Clays
Authors: Osterman Justus 
Published: August 2006

AbstractIn a natural clay, the occurrence of a high sensitivity, i.e. a high quotient between the shear strength of the undisturbed and remolded soils respectively, under undrained conditions, is connected to thixotropic effects and to “quickness”.The general composition of the soils in which quick clay occurs is described, and mention is made of the occurrence of non-argillaceous rock fragments in a matrix of clay particles. Mite is the main clay mineral. Quickness occurs both in salt-leached, marine deposited clays and in clays deposited in fresh water. The pore water of these clays is low in electrolytes and undecomposed organic material. It is found that quick clays often occur near peat and similar humic deposits. Also briefly discussed is the internal stress distribution in natural clays under various consolidation conditions, the structure of quick clays and their conditions of formation. The consistency of clays is considered, as is the stability and coagulation conditions of suspensions. This is followed by a commentary on physico-chemical effects contributing to the formation of quick clays under natural conditions, and a discussion of the salt-leaching theory and the theory on the effect of peptizing agents.In the discussion, the author draws parallels between the coagulation and the thixotropic phenomena, and between the stability and dispersion of suspensions and the quickness.