bluuebunny/crossref_metadata_2025_split huggingface dataset:
A lithium-bearing aluminian regular mixed layer montmorillonite-chlorite from Huy, Belgium
Authors: Brown G. , Bourguignon P. , Thorez J. 
Published: December 2006

AbstractA bluish-green clay found in veins cutting across brecciated slates of the Llanvirnian stage at Huy, Belgium, is shown by X-ray diffraction and chemical analysis to be a lithium-bearing, aluminium-rich, regular mixed layer montmorillonite-chlorite with associated pyrophyllite, nacrite and quartz and smaller amounts of calcite and ankerite. The cation exchange capacity of the purified air-dry magnesium saturated clay is 49 mEq/100 g and its structural formula isThe problem of the nomenclature of regular mixed layer montmorillonite-chlorites is discussed.
Illites en lattes, illites pseudohexagonales, processus de formation: experimentation
Authors: Mosser Ch. 
Published: December 2006

RésuméLe Grès à Voltzia des Vosges du Nord est formé de bancs gréseux et de lentilles argileuses. Les illites extraites des bancs gréseux montrent au microscope électronique des formes en lattes alors que celles des lentilles argileuses ont des contours pseudohexagonaux. Lorsqu'on broie une muscovite dans de l'eau désionisée avec du sable de Fontainebleau on retrouve ces deux formes, en lattes et pseudohexagonales. Les deux formes de particules peuvent donc être engendrées par un mème materiel initial.Une hypothèse a été faite quant à la formation des illites en lattes. Elles seraient le résultat d'une dissection de particules micacées le long des rangées de substitution [10], [11] et [1] du silicium tétraédrique par de l'aluminium avec perte d'une partie de cet aluminium. Des analyses chimiques et des observations au microscope électronique ont été faites sur des particules de muscovite broyée. Les résultats obtenus vont dans le sens de l'hypothèse émise mais ne sont pas suffisants pour la démontrer pleinement.
Mineralogical changes associated with deep weathering of gabbro in Aberdeenshire
Authors: Basham I. R. 
Published: December 2006

AbstractThe distribution, profile morphology and mineralogy of deeply weathered gabbroic rocks in the basic igneous masses of Insch and Bogancloch, Aberdeenshire, have been studied. The saprolite is characterized by granular disintegration and spheroidal weathering with a relatively low degree of secondary mineral development. The upper part of the profile often shows evidence of mass movement and incorporation into overlying drift but below this zone the degree of alteration is generally uniform with depth. Feldspar and hornblende are largely unaffected, except by disintegration, but pyroxenes show varying degrees of weathering from the incipient development of amorphous iron oxides to replacement by reticulate networks or complete pseudomorphs of trioctahedral vermiculite. Biotite weathers to hydrobiotite and vermiculite, giving rise also, under certain conditions, to kaolinite-gibbsite vermiforms. The correspondence between occurrences of deep weathering and coarser textured biotite-bearing rocks can be related to the instability of this mineral. Consideration of the mineralogical changes found and the morphology of the profile of weathering suggest their formation under a warm, humid climatic regime, probably during the mid Tertiary times.
Surface acidity of imogolite and allophane
Authors: Henmi T. , Wada K. 
Published: December 2006

AbstractThe acid strength and the number of acid sites on various clays were determined by observing the colouration of Hammett indicators adsorbed on them and by titrating benzene suspensions of them with n-butylamine, respectively. H(Al)-saturated allophane behaves as a strong acid (Ho; −5·6 ∼ 1·5) in a relatively dry environment (relative humidity 10-55%), but its acid strength is very much reduced either by increasing its water content or by saturating it with alkali or alkali earth metal cations. Imogolite shows only a very weak acidity (Ho; 4·6 ∼ 6·8) under medium dry to moist conditions (relative humidity; 30-100%). Both allophane and imogolite show a marked enhancement of acidity (Ho; −8·2 ∼ 1·5) when they have been dried over P2O5 or heated to result in dehydroxylation. H(Al)-saturated montmorillonite, kaolinite and halloysite show stronger acidities (Ho; −5·6 ∼ 1·5) than allophane (Ho; 1·5 ∼ 6·8) in a relatively moist environment (relative humidity; >60%). The n-butylamine titre and CEC show a good agreement for montmorillonite, but a poor agreement for allophane. The latter discrepancy which is larger for allophane when it has been heated at 150 and 300°C, is also found for imogolite when similarly heated. In these titrations, excess butylamine is found in supernatants at end-points. Therefore, the n-butylamine titre as such can not be used for the estimation of the number of acid sites on imogolite and allophane. The origin, structure and transformation of the acid sites on these clays is discussed.
Electron spin resonance studies of doped synthetic kaolinite. I
Authors: Angel B. R. , Jones J. P. E. , Hall Peter L. 
Published: December 2006

AbstractSynthetic kaolinites of varying crystallinity, and in some instances with ideal morphology, have been produced by hydrothermal reaction of aluminiosilicate gels. Synthetic kaolinites doped with Mg2+ and Fe3+ were also obtained.Synthetic kaolinite doped with Fe3+ produced an ESR spectrum at g = 4 identical to spectra observed in natural kaolinites. Following X-irradiation and annealing at ~200°C, synthetic kaolinite doped with Mg2+ exhibited an ESR signal at g = 2·0 identical to a resonance observed in natural kaolinites. It is concluded that the g = 2·0 signal in kaolinite is due to a defect centre stabilized by Mg2+ substitution.All synthetic and natural kaolinites exhibit an additional resonance at g = 2·0 following X-irradiation which can be repeatedly created and destroyed by irradiation and annealing. This resonance is attributed to defects possibly associated either with the substitution of Al3+ for Si4+ in kaolinite or with lattice vacancies.
Electron spin resonance studies of doped synthetic kaolinite. II
Authors: Jones J. P. E. , Angel B. R. , Hall Peter L. 
Published: December 2006

AbstractIt is shown from studies of synthetic kaolinites doped with Fe3+ that the ESR spectrum of kaolinite at g = 4 consists of two components attributed to Fe3+ ions occupying two distinct substitutional sites (Centres I and II). The relative intensity of the two components can be correlated with the X-ray crystallinity of the samples. The ESR spectrum is influenced by artificial changes in crystallinity produced by subjecting samples to high stresses or by intercalation. It is concluded that Centre II is due to Fe3+ replacing Al3+ in the octahedral layer in a region of high crystallinity. Centre I is assigned to Fe3+ occupying Al3+ sites distorted by changes in the hydroxyl orientations associated with layer stacking disorder or disruption of interlayer bonding.A stable defect centre in kaolinite which produces an ESR spectrum at g = 2·0 is attributed to either a hole centre located on an Si—O bond adjacent to an Mg2+ octahedral impurity or to an O2− ion trapped within the lattice.
The nature and nomenclature of hydrous nickel-containing silicates
Authors: Brindley G. W. , Maksimovic Z. 
Published: December 2006

AbstractNickel ions play similar roles to magnesium ions in nickel-containing hydrous layer silicates. The extent of the replacement of Mg by Ni ranges from small proportions to complete, or almost complete, replacement. Particular interest attaches to the micro-crystalline, clay grade, minerals formed by processes of lateritic weathering. The multiplicity of names proposed in pre-X-ray-diffraction times must be re-evaluated in terms of modern identification procedures. Many of these minerals can now be placed in series such as:Garnierite is now used mainly as a field term, prior to more specific identification, and terms such as 7 Å- and 10 Å-garnierite are useful when identification can proceed no further than recognition of basal spacings. Further study is required of schuchardtite, and of nickel-containing smectites and sepiolites. Consideration also must be given to the composition ranges of the end-member names.
Maghemite in soils and its origin
Authors: Taylor R. M. , Schwertmann U. 
Published: December 2006

AbstractThe products of air oxidation of mixed Fe(II)-Fe(III) chloride solutions at pH 6 and 7, at 20 and 60°C and at normal pressure contain green rust, maghemite, lepidocrocite, goethite and a paracrystalline ferric hydroxide (ferrihydrite). Among these maghemite, a cubic ferromagnetic iron oxide (Fe2O3) found in many soils, is favoured by slow oxidation rate, high total Fe concentration, the presence of small amounts of Fe(III) in the original predominantly Fe(II) solution, higher temperature and at pH 7 rather than pH 6. The green rust is believed to be an essential precursor of maghemite. On slow oxidation it will form maghemite probably via magnetite. Fast oxidation prevents the cubic phase from being formed and lepidocrocite is the end product. At higher Fe(III) proportions ferrihydrite can be formed which under certain influences converts to goethite and/or hematite. The common iron oxides are seen to form from the same system from small variations in environment which is to be expected from their common associations in soils
Clay mineralogy of sediments of the western Nile Delta
Authors: Weir A. H. , Ormerod E. C. , El Mansey I. M. I. 
Published: December 2006

AbstractInvestigation of the clay mineralogy of forty-seven samples of sediments from boreholes in the western Nile Delta, an area little studied hitherto, and from surface sites on the mouth of the Nile and adjacent coast shows that the clay fractions consist of dominant iron-rich, dioctahedral, randomly interstratified smectite-illitcs together with kaolinite, illite and chlorite.Amounts of the constituent minerals of the clay fractions are estimated from their X-ray diffraction intensities, supported by selective dissolution chemical data, and a new method is used to estimate the proportion of expanding layers in randomly interstratified smectite-illite. The results, which confirm and extend the work of previous investigators, also show that there is little correlation between the clay mineral composition and texture of the sediments, only kaolinite being weakly linearly correlated with clay content. Transformation of 2:1 layer silicate minerals occurs within the buried sediments ; chlorite is transformed and smectite and illite interlayers redistributed within randomly interstratified smectite-illites.
Chlorite and illite in some lower Palaeozoic mudstones of mid-Wales
Authors: Evans L. J. , Adams W. A. 
Published: December 2006

AbstractLower Palaeozoic mudstones from Cwmcadian, Gwynedd are dominantly composed of quartz, illite and chlorite, with subordinate albite, orthoclase and rutile. Chemical formulae are determined for chlorite and illite using a combination of chemical and X-ray data. The formulae indicate that the illite is dioctahedral and suggest that the chlorite structure contains one dioctahedral and one trioctahedral layer. The hypothesis is put forward that both minerals formed from a dioctahedral mineral; illite from a non-expanded form and chlorite from an 'open' form by precipitation of a Fe2+/Mg hydroxide interlayer.
Lath-shaped montmorillonites in Surrey
Authors: Neumann Barbara S. 
Published: December 2006

AbstractElectron microscopic examination of montmorillonite from the deposit near Redhill shows that the particles of the so-called blue clay are predominantly lathshaped with an average length: width ratio of 5. The so-called yellow clay from Redhill also contains a high proportion of similar lath-shaped particles, but many smaller lamellar particles are present which appear to be the results of lateral fracture of the laths. The majority of particles of montmorillonite in the fullers' earth deposit near Bath, Somerset, are platy with a similar shape distribution to Wyoming Bentonite, although smaller in size.The electron microscopic technique used is based on a positively charged supporting film which, immersed in a clay suspension, preferentially selects negatively charged montmorillonite from the predominantly uncharged impurities. A conventional replica technique also showed lath-shaped particles in the blue clay.The possible practical consequences of the different particle shapes are discussed.
Influence de la stereochimie des diols sur la formation des complexes interfoliaires de la montmorillonite calcique
Authors: Chassin P. 
Published: December 2006

RésuméDans ce travail, nous avons determine les caractéristiques des états d'équilibre de la montmorillonite calcique placée dans la phase vapeur délivrée par des solutions aqueuses d'éthane 1·2 diol, de propane 1·2 diol, de propane 1·3 diol, de butane 1·3 diol, de butane 1·4 diol et de butane 2-3 diol.Les diagrammes de sélectivité, calculés à partir des isothermes d'adsorption, la diffraction des rayons X et la spectroscopic infrarouge mettent en evidence l'existence de deux phases adsorbées ayant des caractéristiques très différentes.(1)Une phase interagrégat dont la composition est égale à celle de la solution d'équilibre.(2)Une phase interfoliaire dont les caractéristiques sont étroitement liées à la stéréochimie de la molécule organique.Les différents états stables mis en evidence s'expliquent par les energies mises en jeu par les interactions cations dipoles et les liaisons hydrogène intermoléculaires.
Signification de la mesure des surfaces totales des argiles avec l'ethane 1·2 diol
Authors: Chassin P. 
Published: December 2006

RésuméL'exploitation des diagrammes de sélectivité de la montmorillonite, en equilibra avec la phase vapeur délivrée par des solutions aqueuses d'éthane 1-2 diol, permet de montrer que la quantité de diol interfoliaire est supérieure a 25 % et qu'elle est directement reliée à la chaleur d'hydratation des cations compensateurs.Les cinétiques de désorption, réalisées à plusieurs températures, permettent de retrouver les mèmes résultats, à savoir que l'encombrement moléculaire depend du cation compensateur.Ainsi, la mesure des surfaces totales des minéraux argileux avec l'éthane 1·2 diol n'a de sens que si, d'une part, on opere toujours avec le mème cation (σm = cte) et, d'autre part, on determine la quantité de diol en contact avec la surface à partir de plusieurs cinétiques de désorption réalisées à différentes temperatures.
Observations on the formation of kaolinite in the St. Austell granite, Cornwall
Authors: Exley C. S. 
Published: December 2006

AbstractPartial chemical and X-ray analyses of specimens taken serially from three different rock types from the St. Austell granite show that potash feldspar is hydrothermally altered to a micaceous mineral. Sodic plagioclase alters to mica, montmorillonite and kaolinite. Furthermore, in the latter case the micaceous mineral and montmorillonite are intermediate products between feldspar and kaolinite. It is believed that the level of H+ion activity in the altering solutions controlled the removal of alkalis, Al2O3and SiO2so as to leave appropriate concentrations of these constituents to re-form as mica or montmorillonite. Further alteration of a similar kind produced kaolinite.
Polymerisation en phase aqueuse d'acides amines sur des argiles
Authors: Brack André 
Published: December 2006

RésuméL'action catalytique des argiles sur la polymérisation des acides aminés en solution aqueuse a été étudiée. Les résultats rapportés par Katchalsky et coll. dans le cas de la polymérisation de l'analyl adenylate en presence de montmorillonite n'ont pu ètre reproduits. D'autres types d'activation des acides aminés ont été examines.
Smectite, chlorite and a regular interlayered chlorite-vermiculite in soils developed on a small serpentinite body Massif Central, France
Authors: Ducloux J. , Meunier A. , Velde B. 
Published: December 2006

AbstractThree soil profiles developed on a serpentinite body (La Rochel'Abeille, near Limoges) show three stages of weathering. All soils contain iron-rich smectites and secondary chlorites. The latter are very silica-rich, more so than 14 Å chlorites from crystalline rocks. In the (B)1g horizon of the hydromorphic profile, these minerals seem to give a reaction of the type:This reaction, typical of a closed system, appears to be operative in a soil profile which is certainly, in part, open to chemical migration. The chemistry of the weathered serpentinite and the chemical composition of newly formed minerals as well as those of the serpentinite are used to indicate the chemiographic relations of clay minerals formed in the weathering profiles.
Mineral reactions at grain contacts in early stages of granite weathering
Authors: Meunier A. , Velde B. 
Published: December 2006

AbstractTwo outcrops were studied which showed granite in the early stages of weathering. Reactions between specific mineral species were observed, and especially the formation of an illite-like phase which is similar to that of sedimentary illite. This phase has a composition distinct from that of the initial micas in the rocks, notably in its iron and magnesium content. This suggests solution-solid equilibria which involve ionic transfer beyond the grain bondary region where the mineral is found.
Weathering of clay minerals in a Navarre andosol (Spain)
Authors: Barragan E. , Iñiguez J. 
Published: December 2006

AbstractThe evolution of clay minerals in a Navarre Andosol (Spain) is investigated. The results indicate formation of allophane, evolution of trioctahedral mica to dioctahedral illite and the appearance of 10:14 A interstratified mineral in the lower layer. In the top horizons the interstratified mineral changes into vermiculite. The mineral distribution in the profile is indicated.
Zur Mineralogie, Kristallchemie und Geochemie Kretazischer Glaukonite
Authors: Kohler Ewald E. , Koster Heinrich M. 
Published: December 2006

ZusammenfassungGlaukonitglimmer von 10 kretazischen Gesteinen werden mineralogisch und chemisch untersucht. Die von den Glaukonitkòrnern und Glimmern der Kolloidtonfraktion errechneten Strukturformeln der Glaukonitglimmer bestàtigen die Glaukonitglimmer als exakt dioktaedrische Minerale. Die Strukturformeln geben nur Mittelwerte der Verteilung der chemischen Hauptbestandteile und der Kationenladung der Glaukonitstruktur an. Innerhalb des Konzentrationsdreieckes Muskowit-Seladonit-Pyrophyllit deckt sich das Areal der Glaukonite mit dem der Illite, wenn auf den Seiten des Dreieckdiagrammes die Kationenladungen der Tetraeder-, Oktaeder- und Zwischenschichten aufgetragen werden. Entsprechend der iibereinstimmenden Verteilung der Kationenladungen in der Glaukonit- und Illitstruktur kònnen die Glaukonite als die eisenreichen Àquivalente der Illite angesehen werden. Der Gehalt an Spurenelementen in Glaukoniten ist, abgesehen vom Bor, deutlich geringer als in Biotiten und Muskowiten. Die chemische und strukturelle Inhomogenitat der Glaukonite in den Gesteinen wird am besten durch eine Entstehung der Glaukonite aus Gelen im Sediment erklàrt.
Influence des substances humiques sur les propriétés des argiles
Authors: Chassin Pierre , Le Berre Brigitte , Nakaya Norio 
Published: December 2006

RésuméAprès avoir rappelé l'importance du mode de préparation des associations montmorillonite-acides humiques sur leurs propriétés d'hydratation, nous présentons les résultats obtenus par adsorption d'azote.L'ensemble des résultats obtenus sur ces associations indique que la localisation de la matière organique dans l'espace poral de l'argile joue un grand rôle, localisation qui varie avec le mode de préparation des échantillons et la teneur en carbone.On donne une interprétation générale des courbes représentant la variation des quantités d'eau fixées par ces associations, quand la teneur en carbone augmente.
The location and content of iron in natural biotites and phlogopites: a comparison of several methods
Authors: Sanz Jesus , Meyers Jacques , Vielvoye Léon , Stone William E. E. 
Published: December 2006

AbstractMössbauer spectra have been obtained at room temperature on a series of phlogopites and biotites which have also been characterized by chemical analyses, I.R. and N.M.R. The distribution of the Fe2+ ions on the two possible octahedral sites is on the average nearly random. A clear example of tetrahedrally coordinated Fe3+ ions in a natural phlogopite is given. This phlogopite has a very high vermiculitization ability. The Fe3+ content of the samples has been determined by two different chemical methods and it is shown that even when precautions are taken to minimize oxidation, the agreement with Mössbauer spectra is poor.
Calculated X-ray diffraction curves for the interpretation of a three-component interstratified system
Authors: Cradwick P. D. , Wilson M. J. 
Published: December 2006

AbstractThree-component interstratification of layer silicate minerals in the clay fractions of soils and sediments is probably more common than is generally realized. However, interpretation of the proportion and arrangement of the various components from experimentally recorded X-ray diffraction curves is difficult and in this paper a series of calculated diffraction patterns are presented which illustrate the types of diffraction patterns obtained from interstratified mica-vermiculite-montmorillonite systems.
An occurrence of polymorphic halloysite in granite saprolite of the Bayerischer Wald, Germany
Authors: Wilke B.-M. , Schwertmann U. , Murad E. 
Published: December 2006

AbstractXRD, DTA and IR patterns showed clay veins filling fissures in a granite of the Bayerischer Wald (eastern Bavaria) to consist mainly of hydrated halloysite of low crystallinity with traces of gibbsite, 2:1 (mixed layer) clay minerals and iron oxides. The halloysite forms thin plates which exhibit varying degrees and types of enrolment, resulting in platy, tubular and spheroidal crystals within the same sample. Concentrations of the trace elements Rb, Sr, Ba, Zr, Y, Ce, Pb, Zn and Cu indicate halloysite formation to have taken place via an aqueous phase under the influence of vadose waters circulating in fissures.
The effect of Fe-for-Si substitution on the b-dimension of nontronite
Authors: Russell J. D. , Clark D. R. 
Published: December 2006

AbstractA survey of 060 spacings of dioctahedral smectites has shown that for nontronites with only iron on octahedral sites, a linear relationship exists between the b-axial dimension and the number of atoms of tetrahedrally coordinated Fe3+ per unit cell containing O20(OH)4. The slope, 0·0497 Å/Fe3+, is steeper than that for the increase in b resulting from Fe3+ on octahedral sites, 0·0377 Å/Fe3+, demonstrating the greater importance of tetrahedral substitution in influencing b. Factors that take account of the number of Fe3+ atoms on tetrahedral sites have been incorporated in existing formulae for calculating b-axis cell dimensions for smectites, but these are usually less successful in predicting b than a new formula involving only tetrahedral and octahedral iron contents.