bluuebunny/crossref_metadata_2025_split huggingface dataset:
An unusual weathered profile from Orange, N.S.W., Australia
Authors: Bayliss Peter 
Published: December 2006

AbstractSamples were collected from a 11·4 m deep weathered profile of a metamorphic rock. The mineralogy was determined from XRD powder patterns, differential thermal and thermogravimetric analyses with CEC determinations and chemical analyses.Four stages in a weathering sequence from the profile base towards the surface are as follows : (i) a partially regular trioctahedral chlorite-chlorite mixed layer ; (ii) a random chlorite-vermiculite mixed layer; (iii) a random chlorite-smectite mixed layer, and finally (iv) a smectite. Some chloritic layers are therefore more resistant to chemical weathering than other chloritic layers. This profile indicates that the order of decreasing resistance to chemical weathering is talc > smectite > tremolite.
Hydratation des smectites et demixtion des cations Li, Na en fonction de la localisation des substitutions isomorphiques
Authors: Glaeser R. , Fripiat J. J. 
Published: December 2006

RésuméPar l'étude de la variation de la charge réticulaire relative et de la surface spécifique relative, accessible à l'eau, de smectites ayant subì l'effet Hofmann-Klemen à différents degrés, on montre que celles caractérisées par des substitutions tétraédriques (Beidellite B de Rupsroth et Ascan-gel) se différencient clairement de l'Ascan-argile qui ne contient que des substitutions en couche octaédrique. Dans la beidellite, la démixtion des cations Li, Na est totale pour toutes les compositions de la garniture cationique tandis que la démixtion n'apparaìt dans le cas de la montmorillonite que si (Na+/Li+) < 0·75. L'Ascan-gel occupe une position intermédiaire. Ces observations sont interprétées comme une indication que les substitutions tétraédriques empèchent l'expansion des feuillets en suspension.
Use of flocculated fraction of calcareous soil suspensions after ultrasonic treatment for mineralogical study
Authors: Heakal M. S. , Herbillon A. J. 
Published: December 2006

AbstractSeparation of the clay fraction from a calcareous soil usually involves chemical pretreatments which could affect the separated clays. A technique based on separating the flocculated particles (flocs) of a sonified soil-water suspension was used on highly calcareous samples and a highly gypseous one collected from a limestone ridge in Egypt. The relative abundance of the clay minerals in flocs (identified by XRD and electron microscopy) was found to be identical to that of < 1 μm clay separated by sedimentation. The suspensions were prepared by washing the soils repeatedly with distilled water (about 2 1/g) until spontaneous peptization.Washing removed both 'amorphous' silica and alumina as detected in the flocs. The composition of poorly-ordered aluminosilicates (SiO2/Al2O3) of the 1μm clays was heterogeneous whereas in the flocs it was homogeneous.Fluoride reactivity of both clay separates and prepared mixtures of CaCO3 with palygorskite (the dominant clay mineral present) was also studied.
Amorphous ferri-aluminosilicates in some tropical ferruginous soils
Authors: Krishna Murti G. S. R. , Sarma V. A. K. , Rengasamy P. 
Published: December 2006

AbstractThe amorphous mineral selectively dissolved from the clay (<2 μm) fractions of twenty-six ferruginous soils contains considerable iron in addition to silicon and aluminium. SiO2/Al2O3 and SiO2/R2O3 molar ratios are between 2·03-3·52 and 1·72-2·95 respectively. The model of the amorphous ferri-aluminosilicate (AFAS) consists mainly of negatively charged tetrahedrally coordinated silica-alumina phase Si3AlO6(OH)4 containing domains of neutral FeOOH, with an outer positively charged hydroxyaluminium polymeric component [Al(OH)2.5]n.The calculated hydroxyl water content of the AFAS averages 17·8%; cation exchange capacity varies from 48·6 to 112·0 mEq/100 g and shows a negative correlation with the outer hydroxyaluminium octahedral component and a positive correlation with the ratio of the tetrahedral Si-Al component to the octahedral hydroxyaluminium component. The K-fixation capacity (1·9-6·1 mEq/100 g) of the AFAS does not appear to be related to the chemical composition. The genesis of the amorphous mineral is discussed.
A Mössbauer study of the weathering of hornblende
Authors: Goodman B. A. , Wilson M. J. 
Published: December 2006

AbstractThe behaviour of iron in the natural weathering of hornblende in a sedentary soil profile has been investigated using the Mòssbauer effect. The spectra from samples at different stages of weathering show appreciable differences which can be accounted for if ferrous iron is lost preferentially from M(3) sites where it is coordinated to hydroxyl groups in a trans arrangement. Unlike biotite the proportion of ferric iron does not increase during weathering and this illustrates the difficulty with which the ferrous iron is oxidized in the amphibole structure.
Problems in layer-charge determination of montmorillonites
Authors: Lagaly G. , Fernandez Gonzalez M. , Weiss Armin 
Published: December 2006

AbstractSpanish montmorillonites from Frente Archidona were used to demonstrate the determination of charge density, CEC and, in mixtures, the montmorillonite content by the aikylammonium method. Special attention is directed to heterogeneous montmorillonites and the determination of the charge density distribution. Some problems which arise by application of the method are discussed: relations between layer charge and cation densities, particle size corrections, microstructures and unsymmetric charge distributions in the interlayer spaces.
The Influence of [Fe(II)], [Si], and pH on the formation of lepidocrocite and ferrihydrite during oxidation of aqueous FeCl2 solutions
Authors: Schwertmann U. , Thalmann H. 
Published: December 2006

AbstractLepidocrocite was synthesized from the oxidation of FeCl2 solutions with and without soluble Si and at various Fe(II) concentrations and pH. Pure well crystallized lepidocrocite was only obtained if CO2 was excluded (to prevent goethite formation) and if pH was kept between 5 and 7 (to prevent maghemite and ferrihydrite formation). Si in solution prevented crystallization of lepidocrocite with increasing Si/Fe atomic ratio (varied between 0 and 0·156) and at the same ratio with decreasing pH. Most of the Si added is probably included in the lepidocrocite and ferrihydrite structure (up to 4·4% Si) and these Si contents are linearly correlated with the initial Si/Fe ratio. No indication from XRD and i.r. spectroscopy was found for changes in the lepidocrocite structure due to Si uptake. The ferrihydrite containing 4·35% Si showed a broad Si-O-stretching vibration which in contrast to pure silica (1080 cm−1) is shifted to lower frequencies (940 cm−1) indicating some Si-O-Fe bonds.
Iron in kaolinite with special reference to kaolinite from tropical soils
Authors: Herbillon A. J. , Mestdagh M. M. , Vielvoye L. , Derouane E. G. 
Published: December 2006

AbstractThe location of iron in five deferrated soil kaolinites and several reference samples has been investigated using chemical analyses, acid dissolution and electron paramagnetic resonance spectroscopy.The iron of most of the kaolinites can be divided into a 'structural iron' content, measured by the amount of iron, dissolved at the same rate as aluminium by acid attack, and a 'resistant iron' content, which is concentrated with the residues.Integration of the geff~4 resonance bands of the electron paramagnetic resonance (EPR) spectra allows a semiquantitative estimate of the 'structural iron' in the samples. A multiple relationship seems to exist between the crystallinity index, the 'structural iron' content and the shape and intensity of both geff~4 and geff~2 EPR signals. The tropical soil kaolinites are a peculiar category with a high content of iron (>2% structural Fe2O3) fire-clay kaolinite, low crystallinity and a specific EPR spectrum exhibiting strong geff~4 resonance bands and no or weak geff~2 sharp doublet.
Beidelltie clay from Chang-yuan, Taiwan; geology and mineralogy
Authors: Chen Pei-Yuan , Wan Hsien-Ming , Brindley G. W. 
Published: December 2006

AbstractBeidellite clays near Chang-yuan, 80 km south of Hwalien, form vein-like bodies 5-10 m wide and 20-45 m deep. Andesitic rocks have been fractured by faulting permitting hydrothermal solutions to percolate and produce an altered mineral assemblage in which beidellite is associated with a mixed-layer illite-smectite, kaolinite, dusty pyrite, microquartz, cristobalite, calcite and dolomite, plagioclase, and gypsum. Ca-clay is common on outcrops and subsurface, where the clay is leached, Na-clay is found; some outcrops are partly kaolinized. Chemical analyses of the beidellite show that the structure is charged predominantly in the tetrahedral sheets. Exchange capacities are mainly in the range 120-140 mEq/100 g clay (110°C); exchangeable cations are Na ≫ Ca ≃ Mg > K. After K saturation and heating, ten samples still expand to near 17 A with ethylene glycol, but the two samples with the highest tetrahedral charge expand only to 14·6-15·0 Å although their total charge is similar to the other samples.
Influencia de la materia organica en la genesis de gibsita y caolinita en suelos graniticos del centro-oeste de España
Authors: Gallardo Lancho J. , Sanchez Camazano M. , Saavedra Alonso J. , Garcia Sanchez Y. A. 
Published: December 2006

ResumenTornando corno base las conclusiones obtenidas en trabajos anteriores sobre las variables significativas en la genesis de gibsita bajo clima templado, se han seleccionado cinco perfiles de alteration de granitos. En esas condiciones los datos termodinàmicos indican que este mineral no puede originarse nunca por un proceso de hidrólisis tipicamente inorgànica. El mecanismo propuesto, complejación del aluminio con àcidos fùlvicos y posterior evolución a gibsita, se muestra corno el mas probable. Se sugiere también que està gibsita puede combinarse con silice para dar lugar a caolinita. Ambos minerales, pues, tienen un posible origen esencialmente orgànico. Este hecho explica la vinculación caolinita y/o gibsita con determinados tipos de vegetación.
Kernmagnetische resonanzmessungen an Glaukoniten
Authors: Kohler Ewald E. , Burkert P.K. 
Published: December 2006

ZusammenfassungBei der Untersuchung von 6 Glaukonitproben mit Hilfe der ‘H-Kernresonanz-Spektroskopie zeigen sich deutlich zwei verschieden gebundene OH-Gruppierungen. Wàhrend die relativ scharfen Signale A auf die in der Oktaederschicht flxierten zwei OH-Gruppen zuriickzufuhren sind, muB fiir die anderen OH-Gruppen des breiteren Signals B eine andere Bindungsnatur gefordert werden. Es ist móglich, dafl es sich bei den OH-Gruppen des Signals B ebenfalls um verschieden gebundene OH-Gruppen handelt und zwar um solche, die an Eisenhydroxid- Verunreinigungen gebunden sind und solche, die zwischenschichtlich in Form von Eisen-Hydroxo-Komplexen gebunden sind. Eine Unterscheidung zwischen letzteren beiden Mòglichkeiten ist aber nicht mòglich.
Influence of uniformly dispersed mineralizers on firing and mechanical resistance of clay ceramics
Authors: Lemaitre J. , Bulens M. , Delmon B. 
Published: December 2006

AbstractSome parameters of the firing of kaolin around 900°C are examined: (1) firing shrinkage; (2) densification, hardening and textural evolution of kaolin ceramics. Experimental results are accounted for by an empirical formula describing the isotherm firing shrinkage of kaolin ceramics.Depending on the precursor salt added, the spreading and dispersion of the mineralizer is more or less homogeneous. If, during thermal decomposition, the salt induces much porosity, this effect can counterbalance the shrinkage caused by the mineralizer. The kinetics of shrinkage, and the final density after firing depend both on the latter effects and on the mineralizer cation. A very good correlation is observed between shrinkage, final density (residual pore volume) and the strength of the fired clay product. The introduction of uniformly dispersed mineralizers causes an increase in mechanical resistance (for identical temperatures and firing times) by a factor greater than 3, occasionally 5) and, for equal firing times and mechanical strengths, lowers the firing temperature by 100-200°C.
The 14 Å phase developed in heated dickites
Authors: Brindley G. W. , Wan Hsien-Ming 
Published: December 2006

AbstractDickites with well-ordered crystal structures and with relatively high dehydroxylation temperatures develop a 14 Å phase when heated to temperatures in the range 550–800°C. The actual spacing is close to 13·7–13·8 Å. Dickites with less well-ordered structures and with lower dehydration temperatures give less development of this phase or none at all. Other kaolinite group minerals do not produce a similar phase. Thermal weight-change and differential thermal analysis data show that the 14 Å phase develops to a maximum as hydroxyl ions are eliminated from the dickite structure and infrared spectroscopic data are consistent with this result. AIKα fluorescence wavelength measurements indicate that the Al ions are in four-fold coordination in the 14 Å phase. Absence of other diffraction data makes structure analysis impossible. The description ‘chlorite-like’ for the 14 Å phase is of questionable validity.
Zur Mineralogie, Kristallchemie und Geochemie einiger Montmorillonite aus Bentoniten
Authors: Vogt Klaus , Köster Heinrich M. 
Published: December 2006

ZusammenfassungDioktaedrische Smektite aus 19 Bentonitproben werden abgetrennt. Aus den chemischen Analysen errechnen sich unter Berücksichtigung der direkt gemessenen Zwischenschichtladungen (nach Lagaly & Weiss, 1971) kristallchemische Strukturformeln von exakt dioktaedrischen Mineralen. Die Tetraederzentren in der Struktur sind fast ausschliesslich von Si4+ besetzt; nur zwei der untersuchten Minerale zeigen eine beidellitische Komponente. Die gemessenen mittleren Zwischenschichtladungen der Montmorillonite (0·33 bis 0·39) ergeben sich allein aus der oktaedrischen Substitution von Me3+ durch Me2+. Im Gegensatz zu der grossen Variation der Strukturformeln von dioktaedrischen Smektiten in der älteren Literatur sind die kristallchemischen Unterschiede der hier untersuchten gereinigten Smektite sehr klein.Im Vergleich zu den Rohbentoniten sind die Konzentrationen der meisten Spurenelemente in den abgetrennten Montmorilloniten erheblich verringert. Nur Mn, Zn, Co und Ni scheinen in die Kristallstruktur eingebaut zu sein. Die übrigen analysierten Spurenelemente sind adsorbtiv gebunden oder in akzessorischen Mineralen enthalten.
Chemistry and mineralogy of some Lower and Middle Chalks from Givendale, East Yorkshire
Authors: Pitman J. I. 
Published: December 2006

AbstractThe chemical composition of nine samples of Lower and Middle Chalk from the Givendale area of Yorkshire was determined; acetic acid residues were mechanically, chemically and mineralogically analysed. All nine chalk samples proved to be exceptionally pure calcium carbonate (96±1·5%), with only small amounts of MgO (1·03±0·53%), Al2O2 (0·33±0·28%) and Fe2O2 (0·20±0·14%). Insoluble residues ranged from 1·07 to 4·46%. Clay formed 56–88% of the insoluble residue. The non-clay fraction consisted of flint, quartz, collophane, limonite, feldspar, tourmaline and zircon. The clay fractions were dominated by montmorillonite (50%) with secondary illite (30%), apatite (3%), and quartz (8–30%). Kaolinite was detected by X-ray diffraction in the Lower Chalk.
Silicifications and associated clay assemblages in the cretaceous marine sediments of southern england
Authors: Jeans C. V. 
Published: December 2006

AbstractSilicifications and smectite-dominated clay assemblages are associated in the marine Cretaceous sediments of England. Both are neoformed, and have developed at approximately the same time in the host sediment. Two silicification types, opal-CT and α-quartz, have a distribution pattern unrelated to the stratigraphy or lithology of the Lower Greensand, Upper Greensand and Lower Chalk. The petrography of five examples suggest that the two silicification types were both precipitated from the porewaters of their host sediment, and their silica mineralogy and their associated silicate minerals were controlled generally by the silica concentration of the porewaters and more locally by the pH gradients.
Formation et applications de complexes mica-vermiculite-chlorure de sodium
Authors: Le Dred R. , Wey R. 
Published: December 2006

RésuméUn minéral interstratifié mica-vermiculite en paillettes de 1 à 4 mm2 est traité par des solutions concentrées de chlorure de sodium. Dans ces conditions une adsorption de sel dans les interfeuillets vermiculite se superpose à l'échange d'ions. L'adsorption de sel prédomine en solution concentrée et l'échange d'ions en solution moins concentrée. Des complexes salins sont ainsi obtenus. Ceux-ci possèdent la propriété de gonfler macroscopiquement dans l'eau avec désorption du sel. L'addition d'eau oxygénée aux solutions salines provoque également un gonflement. Cette propriété est utilisée pour la transformation du minéral en vermiculite. Le minéral et la vermiculite gonflés trouvent des applications intéressantes.
Formation de complexes mica-vermiculite-halogenure de metal alcalin
Authors: Le Dred R. , Wey R. 
Published: December 2006

RésuméLa mise en contact d'un minéral interstrafié mica-vermiculite, en paillettes de 1 à 4 mm2, avec une solution concentrée d'halogénure de métal alcalin conduit à un échange d'ions ainsi qu'à une adsorption de sel. L'échange d'ions n'est que partiel et l'adsorption de sel a lieu dans les interfeuillets vermiculite. La teneur du minéral en sel adsorbé dépend de la nature du cation et de l'anion du sel ainsi que de la température de la solution. Les complexes salins obtenus possèdent la propriété de gonfler macroscopiquement dans l'eau avec désorption du sel. Dans les cas des chlorures de lithium, de potassium et d'ammonium, les complexes salins tendent vers des compositions définies.
Diagenesis of illite in argillaceous sediments of the Rhinegraben
Authors: Heling D. 
Published: December 2006

AbstractThe diagenesis of illite from smectite was investigated in relation to temperature on marly shale core samples from different Tertiary stages (depths between 200 and 3000 m) by X-ray and chemical analyses. It is concluded that the alteration of smectite to illite primarily depends on the cumulative energy supply (temperature × time). Small grain size and high potassium concentrations in the pore solutions shorten the time necessary to complete the alteration. Potassium is supplied by decomposition of feldspar within the sediment so that the replacement of feldspar by secondary calcite increases the availability of potassium. Supply of potassium by pore solutions from distant sources is very unlikely due to reduced permeability in compacted shales. Illite diagenesis is influenced by the inherited layer charge of the initial smectite.
Imogolite and proto-imogolite in an Italian soil developed on volcanic ash
Authors: Farmer V. C. , Fraser A. R. , Tait J. M. , Palmieri F. , Violante P. , Nakai M. , Yoshinaga N. 
Published: December 2006

AbstractImogolite has been identified in small amounts in clays from a soil profile developed on pyroclastics of tephrite-bassanite composition. The major part of the fine clay was an allophanic material termed proto-imogolite, characterized by an infrared spectrum with some of the features given by imogolite, including a well-developed band at 346 cm−1. Similar products have been obtained in the laboratory.
Infra red and electron spin resonance studies of clays representative of the sedimentary evolution of the Basin of Autun
Authors: Elsass F. , Olivier D. 
Published: December 2006

AbstractThree samples have been selected to represent the sedimentary variations of the Basin of Autun. IR and ESR techniques have been used to study the sheet composition of the different kinds of clays. The kaolinites are fire clays with two different degrees of crystallinity. The illites have a muscovite origin and belong to the 1 M polytype with mainly tetrahedral Al3+ and Fe3+ substitutions but also with some octahedral Fe3+ substitutions. The dioctahedral phyllosilicates contain mostly divalent and trivalent octahedral substitutions.
Reactivity of a long-spacing ammonium-propionate-kaolinite intercalate toward diol, diamines and quaternary ammonium salts
Authors: Seto H. , Cruz-Cumplido M. I. , Fripiat J. J. 
Published: December 2006

AbstractThis paper describes reactions occurring between the 25.5 Å ammonium propionate (AP) intercalate of a well-crystallized Georgia kaolinite with ethylene glycol, 1-6-diaminohexane and a quaternary amine (QA), namelyAn ethylene glycol kaolinite complex is obtained with a strong d001 reflection at 10.9 Å. Seven 00l orders are observed easily. The IR spectrum shows bands at 3697, 3654 (weak shoulder) 3644 and 3622 cm−1, assigned to OH stretching of kaolinite and a strong OH band of E.G. at 3300 cm−1. No absorption band of AP is observed.The 1.6-diaminohexane product is characterized by two broad reflections at 16.6 and 7.4 Å. Distinct Amide I and Amide II IR bands imply that the carboxyl group of the propionic acid has reacted with the amino group. By treating the AP complex with QA a very stable kaolinite-QA complex suspension in benzene was obtained. On drying an X-ray amorphous solid with no reflection at spacing & 20 Å was obtained. The hydroxyl stretching bands of the original kaolinite are drastically modified, a very strong band at 3560 cm−1, a strong doublet at 3620 and 3605 cm−1 were observed. A weak singlet is obtained at 3695 cm−1. The two OH bending bands are replaced by a single band at 912 cm−1. A complicated set of interactions results in the loss of stacking order about the C-axis, accompanied by some curling of layer packets. A prolonged treatment with water restores the X-ray and IR spectra of the original kaolinite.
Efecto de la deshidratacion sobre las propiedades adsorbentes de la palygorskita y sepiolita
Authors: Fernandez Alvárez T. 
Published: December 2006

ResumenSe estudia el efecto de la deshidratación sobre la superficie especifica y distribución del tamaño de poro en sepiolita y palygorskita. Se emplean las técnicas de A.T.D., A.T.G., adsorción-desorción de nitrógeno y microscopía electrónica.La eliminación del agua higroscópico-zeolitica incrementa en los dos minerales la superficie especifica y la proporción de microporos accesibles a las moléculas de nitrógeno.Con la pérdida del agua de cristalización disminuye, en ambos minerales, la superficie especifica y la proporción de los citados microporos, desapareciendo los de anchura inferior a 7 Å en las próximidades de la eliminación completa de esta clase de agua.La eliminación del agua de constitución origina neuvos descensos de la superficie especifica en la sepiolita de acuerdo con las alteraciones sufridas, puestas de manifesto en al análisis térmico; más acusadas que en la palygorskita.
The reaction of ammonia with vermiculite and hydrobiotite
Authors: Stone M. H. , Wild A. 
Published: December 2006

AbstractThe reaction of ammonia with Mg-saturated vermiculite and hydrobiotite was studied by chemical analysis, X-ray diffraction, and differential thermal analysis, and the hydrobiotite also by infrared spectroscopy. The experimental evidence indicates that ammonia is adsorbed mainly as the ammonium ion, formed partly by reaction with interlayer water and partly by reaction with protons dissociated from octahedral layer hydroxyl groups, giving a single sheet of ions and molecules with irregular interlayer spacing. With large flakes (0.5–1.0 mm) the adsorbed ammonia is strongly retained on heating or on rehydration with water vapour: smaller flakes lose ammonia more readily. Ammonia uptake is related quantitatively to cation exchange capacity with two vermiculites and three hydrobiotites, and to the water content prior to adsorption.Na-saturated vermiculite adsorbs a similar amount of ammonia to the Mg form, but it is mostly desorbed on rehydration. Cu-saturated vermiculite displays intermediate behaviour, with much of the ammonia initially present as a Cu-ammine which slowly reacts to give more ammonium ion.