bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clay Mineralogy of Some Silty Soils of the Inner Coastal Plains of Mississippi
Authors: Nash V. E. , Glenn R. C. 
Published: September 2006

AbstractThe chemical and mineralogical properties of six soils previously believed to be developed from coastal plain sediments were found to be significantly influenced by thin loess overlays and admixtures. The study included two profiles each of the Atwood, Lucedale and Savannah series. Atwood formed primarily in deep loess over coastal plain sediments, Lucedale showed definite loess influence to a depth of 10 in. and possible mixing to a greater depth, whereas the Savannah indicated the presence of slight loess to a depth of 20 in. Both the Atwood and Lucedale soils are well drained, whereas Savannah is moderately well drained and contains a fragipan.The mineralogy of the coarse clay (2-0·2 μm) appeared to be the most diagnostic feature indicating genetic differences among the soils. Montmorillonite in this clay fraction was most abundant in Atwood, diminished in Lucedale and occurred only in trace amounts in Savannah. In both the Atwood and Lucedale soils very little montmorillonite was found at depths of 35 in. where coastal plain influence apparently predominates. Conversely, aluminous vermiculite-chlorite intergrade minerals were least abundant, in Atwood, increased in Lucedale and occurred in greatest amounts in Savannah.Accompanying these changes in mineralogy were corresponding changes in the chemical properties. Although no consistent differences in Ca and Mg content were found between the Atwood and Lucedale soils, both Atwood and Lucedale were much higher in exchangeable Ca and Mg than Savannah. Soil pH and base saturation increased in the order Savannah, Lucedale and Atwood.
An Ultraviolet Spectroscopic Method for Monitoring Surface Acidity of Clay Minerals under Varying Water Content
Authors: Bailey George W. , Karickhoff S. W. 
Published: September 2006

AbstractThe ability of a clay mineral surface to function as an acid is not represented by bulk pH measurements. A method using u.v. analysis and organic indicators has been developed to monitor surface acidity. The u.v. organic indicator method enables sensitive in situ quantification of surface-induced protonation in wet or dry clay systems. The clay preparation procedure used yields reproducible acidic behavior.
Mica-Derived Vermiculites as Unstable Intermediates
Authors: Kittrick J. A. 
Published: September 2006

AbstractStability determinations were made by solubility methods on two trioctahedral mica-derived vermiculites. The phlogopite-derived vermiculite was found to be unstable under acid solution conditions, where stabilities of montmorillonite, kaolinite and gibbsite had previously been determined. An attempt was next made to locate a possible montmorillonite-vermiculite-amorphous silica triple point. This triple point involved conditions of alkaline pH, high pH4SiO4 and high Mg2+. These are conditions where phlogopite and biotite-derived vermiculites are most likely to control equilibria if they are stable minerals. The montmorillonite-vermiculite-amorphous silica samples went to the montmorillonite-magnesite-amorphous silica triple point, leaving no stability area whatsoever for the vermiculites. These large particle-size, trioctahedral, mica-derived vermiculites appear to be unstable under all conditions of room T and P.Arguments are presented indicating that micas are unstable in almost all weathering environments. A hypothesis is proposed that mica-derived vermiculites result from the unique way in which unstable micas degrade in these environments. It is proposed that vermiculite derives from a series of reactions whose relative rates often result in an abundance of vermiculite. These relative reaction rates are slow for mica dissolution, rapid for K removal and other reactions pursuant to vermiculite formation, and slow for vermiculite dissolution. In chemical terms, mica-derived vermiculites may be considered fast-forming unstable intermediates.
Properties of Reduced Charge Montmorillonites: Hydrated Cu(II) Ions as a Spectroscopic Probe
Authors: Clementz David M. , Mortland M. M. , Pinnavaia Thomas J. 
Published: September 2006

AbstractA series of Cu(II) reduced charge montmorillonites (RCM) of varying charge reduction has been prepared by exchange of the parent Li(I)-Na(I) mineral with CuCl2 in 95 per cent ethanol solution. The Cu(II) exchange capacity, as determined by Na(I) exchange in 1:1 (v/v) ethanol-water, is a linear function of the fraction of Li(I) initially present on the exchange sites, F. Selective Cu(II)-saturation on internal and external sites was achieved at maximum charge reduction (F = 1.0). Water sorption isotherms and (001) basal spacings are interpreted in terms of an increasing tendency toward interlayer collapse with increasing charge reduction. Because of the higher hydration energy of the Cu(II) ion, however, the fraction of non-expansible interlayers at a given F value is lower than those present in the corresponding Li(I)-Na(I) RCM. Electron spin resonance spectra of oriented samples show that under air-dried conditions (ca. 40 per cent r.h.) the predominant Cu(II) species present, whether on internal or external sites, is the planar Cu(H2O)2+4 ion. The symmetry axis of the ion is oriented perpendicular to the a-b plane of the silicate sheets. In the presence of a full partial pressure of water, the Cu(II) ions on the external sites and those which are in expansible interlayers become totally hydrated Cu(H2O)2+6 and tumble rapidly. The Cu(H2O)2+4 ions in non-expansible layers retain their restricted orientation on the silicate surface. Some general conclusions have been drawn regarding the nature of charge distribution in the mineral.
Interlamellar and Multilayer Nitrogen Sorption by Homoionic Montmorillonites
Authors: Knudson M. I. , McAtee J. L. 
Published: September 2006

AbstractNitrogen sorption by various homoionic montmorillonites was studied at 78°K. The adsorption isotherms in the relative pressure range P/P0= 0.05-0.25 were found to be either Type I or Type II in the BET classification. The nitrogen sorption process was considered to be predominantly interla-mellar when described by a Type I isotherm. With a Type II isotherm, the adsorption was assumed to be predominantly on those surfaces not in the interlamellar regions.It was concluded that only cations within a certain size range promote significant interlamellar nitrogen penetration in montmorillonites. The role of the smaller cations in nitrogen sorption by montmorillonites seems to be their influence on the external aggregate structures. Very large cations tend to clog up the interlamellar pores as well as some of the external voids.
Properties of ‘Swelling’ Chlorite in Some Mesozoic Formations of California
Authors: Post J. L. , Janke N. C. 
Published: September 2006

AbstractSlaty strata and their weathering products comprise a large portion of the geologic formations of the western foothills in the Sierra Nevada, Mid-Northern California. The weathering products of Mesozoic slates in particular, locally known as ‘swelling’ chlorites, have caused numerous problems in road construction.A typical stratigraphic section of slates, which includes ‘swelling’ chlorites, is given for the area of Chili Bar, California, as part of the general geology of the western foothill formations. Remolded slate densities were observed to decrease while measured swelling pressures increased with increasing slate alteration. Swelling pressures in excess of 12.5 psi were observed. Curves are presented in comparison with DTA results showing the effect of alteration on the slate.The results of X-ray diffraction analyses, in correlation with i.r. data, show a typical slate mineral composition for unaltered material of about one-half chlorite with the remainder being about equal portions of muscovite and quartz. The entire chlorite content of the altered slate becomes a regular mixed-layer clay mineral, corrensite, which has been observed to alter to sedimentary vermiculite and Mg-saponite in residual soil. An i.r. absorption peak at 3690 cm-1 characterizes the mixed-layer clay mineral. Heat treatment of the mixed-layer clay mineral structure reduces the 14.3 Å basal spacing to 11.8Å at 540°C, which decreases to 10.6Å at 850°C, disappearing by 1050°C. Procedures are given for direct quantitative analysis of these three-phase mineral systems using simultaneous linear equations.Evidence is presented for the alteration minerals formed during weathering of the slate, including Fourier analysis of the mixed-layer clay structure.
Factors Affecting Selected Area Electron Diffraction Patterns of Micas
Authors: Güven Necip 
Published: September 2006

AbstractMajor factors affecting the selected area electron diffraction (SAD) patterns of micas are: lattice properties of the crystal, specimen thickness, orientation of the crystal, properties of the Ewald sphere for electron diffraction, depth of field of the objective lens, and variations in focusing conditions of this lens. Depending on these factors, SAD patterns of 2M1 muscovite may display different symmetries. Specimen ’finite’ thickness affects the intensity in terms of the ’interference function’. The latter function has been evaluated exactly and the intensity distribution has been calculated along the (hk) rows. The observed intensity variations of (hk) spots indicate that the focusing conditions of the objective lens are rather critical for the symmetry of SAD patterns.
A Comparative Study of Simulated and Natural Weathering of Some Oklahoma Shales
Authors: Laguros J. G. , Kumar Subodh , Annamalai M. 
Published: September 2006

AbstractShales from six locations in Oklahoma were subjected to natural weathering for 2 yr. Simulated weathering of these shales was effected in the laboratory by subjecting them to ultrasonic treatment in a tank type device. Both treatments produced disaggregation. X-ray diffraction patterns for the ultrasoni-cally treated and weathered shales indicated no major changes in the types of clay minerals. However, natural weathering in the field produced degradation of the clay minerals in addition to disaggregation of the shales. Ultrasonic treatment appears to be a good predictive test for determining the durability and weatherability of the shales; however, it can simulate field weathering only so far as the engineering index properties of the shale are concerned. It is not a predictive test where the mineralogical characteristics are of significance.
Crystal Imperfections with Regard to Direction in Kaolinite Mineral
Authors: Williams D. G. , Garey C. L. 
Published: September 2006

AbstractThe crystallite sizes in the particles from four fractions of a kaolinite-clay were determined from the broadening of the X-ray diffraction lines. Measurements were made of the <002> and <111> planes whose crystallographic directions correspond to the clay plate thickness and diagonal, respectively. The extent of crystal imperfection was determined by comparing the calculated crystallite size with the mean size based on measurements from electron micrographs. The crystal imperfections were found to be more extensive in the plate diagonal, <111>, than in the plate face, <002>, directions. Electron micrographs of hydrofluoric acid-etched samples revealed plate-edge and plate-face imperfections. The latter show a regularity suggesting a mosaic-like texture in the plate surface. Surface imperfections probably have significant influence on the dispersion and flocculation behavior of kaolinite.
Electrolyte Concentration-Permeability Relationships in Sodium Illite-Silt Mixtures
Authors: Hardcastle James H. , Mitchell James K. 
Published: September 2006

AbstractTo examine the effects of clay swelling and dispersion on electrolyte concentration-permeability relationships of low clay content soils, flow experiments were conducted on a silt of fixed particle size distribution containing 0, 5, 7·5, 10 and 15 per cent clay (sodium illite, 2 μm fraction). Flocculated specimens were sedimented using both slow and rapid procedures. After compression each specimen was permeated successively with electrolyte solutions which caused (1) swelling of the clay fraction (0·10 N), and (2) dispersion (0·05 N). Absolute permeabilities varied with clay content, sedimentation procedure, compression rate, and electrolyte concentration; however, the form of this variation plotted against through-put volume was similar for all specimens containing electrolyte solutions causing only swelling of the clay. Increasing the hydraulic gradient above a critical value apparently increased the swelling slightly as evidenced by further reductions in permeability. The permeability of mixtures permeated with electrolyte solution causing dispersion of the clay was more complex and depended on clay content, the hydraulic gradients used to introduce the dispersing electrolyte solution and the pre-dispersion gradients to which the specimens had been subjected. Permeability decreases were attributed to the last stages of swelling prior to dispersion and to pore plugging. Increases in permeability were the result of erosion of dispersed particles. Specimens previously subjected to the highest gradients while swelling dispersed more rapidly and had a greater tendency to erode. The effects of predispersion gradients diminished with increasing clay contents. It is concluded that both compositional and mechanical factors play an important role in determining electrolyte concentration-permeability relationships for soils containing active clay minerals.
Electron-Optical Investigations on Montmorillonites—I. Cheto, Camp-Berteaux and Wyoming Montmorillonites
Authors: Güven Necip 
Published: September 2006

AbstractOther layer silicates are consistently present as impurities in natural montmorillonite samples. They have a distinctly different morphology from the common montmorillonite particles. The selected area electron diffraction (SAD) of these impurities display unusually sharp spot patterns with triclinic, monoclinic and hexagonal symmetries. These impurities are most likely micas, which are easily detectable with X-rays in the coarser fractions (> 10 μm) of the samples.The crystal structure model with the space group C2 for montmorillonite single layer has an unusual configuration of OH’s and vacancies for a dioctahedral layer silicate. Our intensity calculations do not bring a conclusive evidence for distinguishing the two possible space groups C2 and C2/m on the observed SAD patterns of montmorillonite.The SAD of the thin montmorillonite flakes in Cheto, Camp-Berteaux and Wyoming samples display uniform ring, circular arcs and spotty ring patterns, respectively. These patterns indicate different modes of association of crystallites or different arrangements of elementary layers within them.
Phosphate Transport in Illite Due to Consolidation
Authors: Moore Charles A. , Zouestiagh Nahid 
Published: September 2006

AbstractThe conditions were studied under which consolidation loading caused the release of phosphate from a saturated illite clay. P32 tracer techniques were employed to follow the movement of phosphate in composite samples composed of tagged and untagged portions. The samples, initially consolidated to 1·0 kgcm−2 stress were reconsolidated to 0·1, 0·5, 2, 4 and 8 kg cm−2 stress and the transport of phosphate was monitored by counting the radioactivity of 0·01-in. thick sections sliced parallel to the major principal plane. Corrections were applied for P32-P31 self-diffusion. It was found that: (1) for low phosphate concentrations there was no observable transport due to consolidation type flow: (2) for high phosphate concentrations and for stresses less than or equal to the preconsolidation load there was no observable transport due to consolidation type flow; and (3) for high phosphate concentrations and for loads above the preconsolidation load there was detectable transport of phosphate, presumably due to the consolidation flow. A mechanism based on self-diffusion plus uniform flow was able to semi-quantatively explain the test results.
Experimental Transformation of a Chlorite Into a Vermiculite
Authors: Ross G. J. , Kodama H. 
Published: September 2006

AbstractAn orthochlorite (sheridanite) was heated to 610°C to dehydroxylate the hydroxide sheet and to oxidize ferrous iron. The heated sample was shaken for 20 min in a mixed solution of 0·2 N HCl and 0·2 N NaCl to dissolve the dehydroxylated hydroxide sheet. X-ray diffraction, thermal, infrared absorption and chemical analyses showed that the resulting product was similar to Kenya vermiculite. The procedure shows promise for the individual determination of the composition of the hydroxide sheet and of the mica layer in the chlorite structure. The experiments indicate that the hydroxide sheet in orthochlorites must be structurally disturbed before it can be selectively removed. In nature, structural disorganization of the hydroxide sheet of chlorite by dehydroxylation and oxidation of ferrous iron might occur during meta-morphic processes, and chlorite to vermiculite transformation could take place during subsequent acid weathering. In pedogenic weathering conditions it is likely that oxidation of ferrous iron plays a major role in initiation of the structural disorder required for the selective removal of the hydroxide sheet in the weathering of chlorite to vermiculite.
Electro-Optic Investigation of the Permanent and Induced Dipoles of Montmorillonite as Affected by Electrolyte Concentration
Authors: Schepers J. S. , Miller Raymond J. 
Published: September 2006

AbstractAn electro-optic birefringence technique was employed to study the orientation mechanism of montmorillonite in an electric field. The instantaneous reversal of the field polarity produced evidence of a low voltage permanent dipole and a high voltage induced dipole. This technique was used to study theeffect ofelectrolyte concentration on the rotational diffusion coefficient, a measure of the rate at which the particles rotate or relax, within the solution, from a preferred orientation. Thus, a measure of the immediate environment of the particles was obtained that is not an average effect for the whole system, yet allows for the full development of the clay-cation-water interactions under the experimental conditions. It was found that particle rotation could be accounted for using the measured particle size and normal water viscosity only when the double layer was fully developed, with no free ions or other perturbations. As soon as perturbations were applied, either by adding salts or applying an electric field, the measured particle size and normal viscosity would not account for the data. Either the rotating moiety has to be larger, that is, be a particle plus a water hull, or the viscosity greater, or in some cases both.
Artificial Alteration of Biotite Into a 14 Å Layer Silicate with Hydroxy-Aluminium Interlayers
Authors: Nagasawa K. , Brown G. , Newman A. C. D. 
Published: September 2006

AbstractBiotite was altered by boiling in 0.2 M A1C13 solution, and the products were examined by X-ray powder and single-crystal diffraction, chemical analysis and thermogravimetry. The altered material is a 14 Å clay mineral with hydroxy-Al interlayers. It has a stacking sequence characteristic of vermiculite and its silicate layers are similar in chemical composition to trioctahedral vermiculite. The results of extracting the interlayer material with sodium citrate solution, X-ray examinations after heating and thermogravimetry show that the interlayer material is composed of Al associated with OH and H2O. The chemistry and kinetics of the alteration reaction and the orientational between the altered and original biotites are also discussed.
Exchangeability of Potassium in Heated Fine-Grained Micaceous Minerals
Authors: Smith S. J. , Scott A. D. 
Published: September 2006

AbstractSamples of several naturally fine-grained micaceous minerals were heated at 450°C for 24 hr (after the effects of other temperatures and heating periods were evaluated with the < 2 μm fraction of Grun-dite) and then characterized in terms of their release of K to NaCl-NaTPB (sodium tetraphenylboron) solutions and other potentially related properties.This heat treatment produced a substantial increase in the amount of K that each mineral released when first placed in the NaCl-NaTPB solution (the greatest increase being 22 m-equiv K/100 g in Marblehead illite). Depending upon the mineral heated, the subsequent rate of K release was increased, decreased or unchanged. Also, all the minerals except glauconite exhibited an increase (ranging from 4 to 38 m-equiv K/100 g) in their maximum degree of K release if they were heated. Thus, it was established that the K release behavior of these minerals is not only subject to appreciable alteration by heat treatments but is altered in a manner that varies with the mineral. The nature of these alterations, however, did not clearly identify an involvement of the other mineral properties that were examined. An increase in NH4- and Cs-exchangeable K occurred when these minerals were heated—presumably as a result of exfoliation. With Morris illite samples, this increase was nearly 28 m-equiv 100 g. Thus, heated samples of these minerals may be useful sinks for the removal of NH4 and Cs in various wastes.
Contributions of Forest Opal and Associated Crystalline Phases to Fine Silt and Clay Fractions of Soils
Authors: Wilding L. P. , Drees L. R. 
Published: September 2006

AbstractThe scanning electron microscope (SEM) is useful in the identification of biogenic opal. Opaline spheres, cups, and scrolled or convoluted sheets were identified in both soil and vegetative isolates. X-ray diffraction analysis indicates that both alpha quartz and cristobalite were co-associated with the amorphous opaline phase synthesized during life metabolism of deciduous tree leaves. Such crystalline phases were most abundant in the 2–5 μm fraction and many consist of anitsotropic rods with parallel extinction or equidimensional bodies with aggregate extinction. Between 2/3 and 3/4 of the total opal isolate from deciduous tree leaves was solubilized when digested for 2–5-min in boiling 0.5 N NaOH. Rate of dissolution was a function of particle-size and tree species. Biogenic opal of forest origin was about 10–15 times more soluble than grass opal, which probably reflects the higher specific surface of the former.
Use of Long-Spacing Alcohols and Alkanes for Calibration of Long Spacings from Layer Silicates, Particularly Clay Minerals
Authors: Brindley G. W. , Wan Hsien Ming 
Published: September 2006

AbstractLattice spacings of layer silicates, particularly clay minerals, may exceed 20 Å. The errors in measuring lattice spacings increase rapidly for spacings greater than about 10 Å and diffraction angles 2θ less than about 10°. Long-chain organic compounds, such as normal alcohols, C14–C20, and normal alkanes (paraffins), C26–C30, provide useful calibrations for lattice spacings in the range 10–50Å. The basal spacings of the calibrating substances are determined from their higher order reflections in the angular range where reflections from quartz and silicon are used as standards.