bluuebunny/crossref_metadata_2025 huggingface dataset:
Swelling minerals in a basalt and its weathering products from Morvern, Scotland: II. Swelling chlorite
Authors: Bain D. C. , Russell J. D.
Published: December 2006

A swelling chlorite from unweathered basalt has been characterized by XRD, IR, DTA and chemical analysis. Its 001 spacing of 14.9 Å increases to 18.0 Å on treatment with glycerol and decreases to 13.9 Å (with a broad diffraction effect at 14-10Å) after heating to 550°C. The mineral has an 060 spacing of 1.537Å consistent with a trioctahedral composition, but its OH stretching band at 3638 cm−1 does not show the expected pleochroism, suggesting an anomalous hydroxide sheet which chemical analysis shows is incomplete. Although the mineral has a CEC of ∼50 mEq/100 g, smectite is not present, but all the techniques show that the mineral has some saponitic character, indicating that it probably has a structure intermediate between swelling chlorite and saponite.
Weathering of glauconites: reversal of the glauconitization process in a soil profile in western France
Authors: Courbe C. , Velde B. , Meunier A.
Published: December 2006

Polarizing microscope, electron microprobe and X-ray diffraction examination of minerals in a soil profile developed on a glauconite sand indicate that destabilization of glauconite can be a progressive process which appears to be the reverse of glauconitization. Glauconite in these soils appears to be destabilized into a mixed-layer glauconite-nontronite phase, which crystallizes as a plasma mineral. This material in turn is transformed into smectite+kaolinite+oxides. Loss of K and Fe is evident in whole rock as well as microprobe analyses of the samples. Thus glauconite can lose both Fe and K to aqueous solution during weathering, leaving aluminous clay minerals in the soil.
Etude par activation neutronique de la distribution de quelques elements de transition entre gel silicate et solution aqueuse
Authors: Perruchot A. , Delbove F. , Joron J. L.
Published: December 2006

Une étude expérimentale des équilibres d'échange entre gel de composition (A,B)O-SiO2-nH2O et solution aqueuse (A2+, B2+) a été réalisée avec les couples (A,B) suivants: Mn-Mg, Co-Mg, Co-Mn et Cu-Ni. Les coefficients de distribution (A/B)gel/(A2+/B2+)sol obtenus sont énormes, l'élément A se fixant presque totalement dans le gel et n'apparaissant le plus souvent qu'en traces dans la solution. Le dosage de celles-ci par activation neutronique a permis d'atteindre le domaine des concentrations où ces gels présentent un comportement idéal (loi de Henry) et de mesurer avec une précision accrue les enthalpies libres standard des réactions d'échange correspondantes.
Morphology of kaolinite weathered from a non-feldspathic mica-phyllite
Authors: Keller W. D. , Reichelt M. , Neužil J.
Published: December 2006

The morphology and fabric of kaolin weathered from a non-feldspathic mica-phyllite in Znojmo, Moravia, are illustrated in scanning electron micrographs. In contrast to accordion-like kaolinite books, or elongate halloysite(?) crystals, commonly developed from feldspar, the kaolinite from the mica-phyllite tends to be individually platy, with highly irregular edges resulting from multiple adjacent crystal comers and re-entrants. Irregular or impaired crystal growth of kaolinite from mica may be due to ‘poisoning’ of kaolinite crystals by vanadium that is common in mica.
Shape selectivity in low-temperature reactions of C6-alkenes catalysed by a Cu2+-exchanged montmorillonite
Authors: Adams J. M. , Bylina A. , Graham S. H.
Published: December 2006

The reactions of ten C6-alkenes over a Cu2+-montmorillonite catalyst have been examined between room temperature and 100°C. The reaction products depend uponinter aliathe branching in the alkene, the position of the double bond, and the temperature. Hex-2-ene,cisandtrans-4-methyl-pent-2-ene and 4-methyl-pent-1-ene do not react at all, whereas 2-methyl-pent-1-ene and 2-methyl-pent-2-ene and 3,3-dimethyl-but-1-ene form alcohols below ∼40°C and dimers at higher temperatures. Hex-1-ene forms the di-2,2′-hexyl ether.
Charges on the surfaces of two chlorites
Authors: Jones Angela A.
Published: December 2006

Two chlorites, sheridanite and clinochlore, have been examined to determine their surface charge characteristics. In order to increase their surface area and to produce a measurable surface charge, the chlorites were treated with 10−3m, 10−2m, and 10−1m HCl in 10−2m MgCl2 solutions. These treatments are shown not to alter the crystallinity of the chlorites and to produce a small pH-dependent negative charge which is not directly related to the total surface area. The clinochlore, (Si6.13Al1.84)(Al1.53FeIII0.53FeII0.18Mg9.52)O20(OH)16, is more readily attacked by the acids than the sheridanite, (Si5.43Al2.55)(Al2.90FeII0.05Mg8.86)O20(OH)16, and also produces material with greater surface area and pH-dependent, negative, surface charge. It is concluded that: (i) isomorphous substitutions in the lattice are not reflected in a permanent surface charge; (ii) the observed surface charge arises not only at the edges of the particles but also at points where the chlorite is predisposed to attack by acids; (iii) in the chlorite-acid system used, anions—probably mainly silicate—block positively charged sites.
An ideal solid solution model for calculating solubility of clay minerals
Authors: Tardy Y. , Fritz B.
Published: December 2006

A method for estimating Gibbs free energies and stabilities of clay minerals is proposed for use with computer programs aimed at calculating the chemical evolution of natural water-rock systems. This is based on (i) a model for ideal solid solutions of a large number of end-member compositions and (ii) a data set of estimated solubility products from 36 end-members. The application of the method to the production of experimental or natural clay stabilities is discussed.
Dehydration-related proton conductivity in kaolinite
Authors: Maiti G.C. , Freund F.
Published: December 2006

Well-crystallized kaolinite was found to exhibit marked proton conductivity at pre-dehydration temperatures. Direct current conductivity and thermopotential measurements were performed. By comparing the results obtained with Au electrodes (proton blocking) to those obtained with Pd electrodes (proton injecting), non-protonic contributions could be separated from proton conductivity. The majority charge carriers appeared to be defect proton (negative sign), corresponding chemically to an O2−replacing OH−in the lattice, but excess protons were also noted (positive sign). Below 275°C the activation energy was of the order of 7–8 kcal mole−1; between 275–450°C it was about 18–20 kcal mole−1. This indicated a two-step defect proton-excess proton conductivity mechanism involving, in succession, the two kinds of OH−in the kaolinite structure: (i) OH−located within the six-membered ring formed by the SiO4tetrahedral sheet, (ii) the close OH−array formed by the octahedral sheet. The conductivity results were supported by IR spectroscopic measurements.
The role of clay minerals in influencing porosity and permeability characteristics in the Bridport Sands of Wytch Farm, Dorset
Authors: Morris K. A. , Shepperd C. M.
Published: December 2006

The Bridport Sands is a widespread marine sandstone of Lower Jurassic age found in much of southern England. It is a very fine grained, moderately sorted quartz-arenite and is characterized by the alternation of friable and hard calcareous-cemented layers. The sands form the upper reservoir in the Wytch Farm Field, Dorset, which is currently producing at the rate of around 4000 barrels per day. Investigation of core material to assess the suitability of water injection for gas/oil recovery has shown that significant reductions of liquid permeability compared to air permeability occur. These reductions vary from 30% or less in the best quality reservoir to more than 70% in low-permeability sandstones. Clay minerals in the Bridport Sands comprise mainly kaolinite and mixed-layer clays of both the illite-chlorite and illite-smectite types. Small amounts of vermiculite and chlorite also occur. The kaolinite is found as loosely-attached, discrete particles, whilst the mixed-layer clays form patchy pore linings. The permeability reductions may be explained by: (i) the adsorption of water and expansion of poorly-crystalline mixed-layer illite-smectites causing blockage of pore space (this reduction is largely reversible) and (ii) the physical movement of authigenic kaolinite crystal aggregates blocking pore-throats (this reduction is largely non-reversible). The pore-size distribution, clay particle sizes, the distribution of the clays within the pore space, and the composition of the clays are all important factors in controlling porosity/permeability relationships and permeability reductions in the friable reservoir intervals in the Bridport Sands.
Significance of clays in the petroleum geology of the Niger Delta
Authors: Lambert-Aikhionbare D. O. , Shaw H. F.
Published: December 2006

Sediments of the Tertiary Akata and Agbada Formations have been studied by mineralogical and petrographic techniques. In the Akata and Agbada shales the clays are largely detrital, with only minimal alteration attributable to the effects of burial diagenesis. Clay minerals occur in minor (<10%) amounts in the reservoir sandstones of the Agbada Formation both as detrital and authigenic phases. There are significant differences between the clay assemblages of the water- and hydrocarbon-bearing sandstones. The latter have lower overall clay contents and authigenic kaolinite, whilst authigenic kaolinite and smectite are present in the water-saturated sandstones. These differences are thought to be related to the early migration of hydrocarbons into the reservoir sands. The causes of the poor degree of cementation in the Agbada sandstones are discussed along with the engineering problems posed by their very friable nature.
Presence d'imogolite dans la composition mineralogique des fractions fines extraites des croutes d'alteration observees sur le basalte de roudadou, pres d'Aurillac, Cantal
Authors: Torrent G. , Dejou J. , Manier M. , Larroque P. , Gibert J. P.
Published: December 2006

Resume

La composition minéralogique de la phase <2 µm de la croûte d'altération de teinte pâele et de quelques millimétres d'épaisseur, développée sur les faces des prismes basaltiques de Roudadou, près d'Aurillac, Cantal, a été étudiée par plusieurs techniques: RX, analyse thermique différentielle, thermogravimétrie, spectroscopie infra-rouge entre 600 et 200 cm−1, mesure des surfaces totales. Cette phase fine est constituée d'une fraction non cristalline relativement réduite et surtout de minéraux argileux cristallisés, parmi lesquels l'imogolite est largement dominante (50%), accompagnée de l'halloysite (30%). Parfois une smectite compléte ce cortège argileux. A notre connaissance, l'imogolite n'avait jamais été identifiée parmi les produits d'altération superficielle des roches volcaniques du Massif Central.
Observation of longitudinal acoustic phonons in layer-silicates by neutron inelastic scattering
Authors: Cebula D. J. , Owen M. C. , Skinner C. , Stirling W. G. , Thomas R. K.
Published: December 2006

The technique of neutron inelastic scattering has demonstrated the presence of longitudinal acoustic phonons in two layer-silicate minerals. Values of the elastic constants determined from the dispersion curves have established the validity of the technique for this class of materials.
Etude par spectroscopie infrarouge et diffraction X des interactions eau-cation-feuillet dans les phases a 14.6, 12.2 Et 10.1 Å D'une saponite-Li de synthese
Authors: Suquet H. , Prost R. , Pezerat H.
Published: December 2006

Resume

La prise en compte simultanée des résultats de diffraction des RX et de spectrométrie infrarouge a permis de préciser la nature des interactions entre l'eau, les cations compensateurs et les feuillets dans les phases à 14.6, 12.2 et 10.1 Å d'une saponite-Li de synthèse. En effet, la diffraction des RX renseigne sur l'espace interfeuillet disponible à l'eau et aux cations compensateurs alors que les perturbations observées sur les fréquences de vibration de valence des hydroxyles de structure apportent des indications sur la nature et la position des atomes situés à l'aplomb des cavités hexagonales. Cette étude a permis de confirmer la présence de cations hydratés (Li-H2O)+ dans les cavités ditrigonales des feuillets de la saponite-Li amené àun état d'hydratation correspondant à la phase à 10.1 Å.
Nomenclature for regular interstratifications
Authors: Bailey S. W.
Published: December 2006

It is now generally accepted that species names can be given to regularly interstratified clay minerals, in accordance with the recommendation of the AIPEA Nomenclature Committee (Brindley & Pedro, 1970). In Part A of this report we suggest (i) criteria for defining the degree of regularity of alternation of different layer types that should merit a name, (ii) data that should be provided for documentation of a regular interstratification, and (iii) some examples of interstratifications that do not merit names. In Part B of the report we apply the suggested criteria to the analysis of regular interstratifications previously reported in the literature, and make recommendation regarding the usage of existing names.
A filtering device for oriented XRD mounts
Authors: Brusewitz Ann Marie
Published: December 2006

In the laboratories of the Geological Survey of Sweden we have for many years used an acid-resistant, stainless steel filtering funnel to prepare ‘oriented’ clay mounts for X-ray diffractometry. The funnel consists of three parts (left and centre foreground of Fig. 1). The circular plate is porous and made of sintered stainless steel and serves as a support for a 47 mm diameter membrane filter. The cylinder is manufactured in two different sizes, 250 ml and 600 ml. The funnel is generally mounted on a suction flask but when the filtrate has to be analysed a suction cloche is preferable.

When many mounts have to be prepared the use of a manifold is practical and time saving. We have adapted the Sartorius six-branch manifold and added a transition tube of stainless steel (right foreground of Fig. 1), threaded to fit the manifold outlet and tightened through a gasket. The funnel itself is mounted on the tube through a rubber stopper. Suction is by a small pump (25 l/min, 0·15 kW). A suction flask is placed between the filter stand and the pump to collect the combined filtrates (Fig. 2).
Reactions of ammonium sulphates with kaolinite and other silicate and oxide minerals
Authors: Bayer G. , Kahr G. , Mueller-Vonmoos M.
Published: December 2006

Interactions of ammonium sulphates and various silicate and oxide minerals have been studied by X-ray heating methods and simultaneous TG-DTA. Kaolinite and other clay minerals were found to be very susceptible to these sulphating treatments, (NH4)3Al(SO4)3, (NH4)Al(SO4)2 and Al2(SO4)3 being formed successively with increasing temperature from 350 to ∼550°C. The same reaction products were obtained on heating mixtures of (NH4)2SO4 and γ-Al2O3, Al(OH)3 and bauxite. Fe-, Mg- and Ti-silicates and oxides gave NH4-double sulphates below 400°C and the corresponding metal sulphates above this temperature.
Phengitization, sericitization and potassium-beidellite in a hydrothermally-altered granite
Authors: Meunier A. , Velde B.
Published: December 2006

X-ray diffraction, optical and microprobe studies of a kaolinized oligoclase—orthoclase—two-mica—granite (Southern Armorican Massif) indicated that low-temperature metasomatism had produced three series of minerals. 1. Partial alteration of muscovite resulted in the formation of ferrous-magnesium-phengite. Biotite was destabilized to a kaolinite-titanium oxide assemblage. 2. Phengite, unreacted muscovite and feldspars recrystallized to an aluminous, magnesian 1M sericite mineral ranging in composition from mica to illite. 3. Feldspars were entirely destabilized to produce the assemblage potassic-beidellite-kaolinite—Al-illite. Kaolinite was the predominant mineral in the most altered rock. A fourth stage of mineral equilibrium was also observed; this occurred after material from stage 3 had been reworked. In this environment, the potassic-beidellite was replaced by a calcic-montmorillonite. Potassic-beidellite was not stable under weathering conditions.
Utilisation du rayonnement synchrotron en diffusion aux petits angles pour l'etude du gonflement des smectites: II. Etude de différents systÈmes eau-smectites en fonction de la température
Authors: Pons C. H. , Rousseaux F. , Tchoubar D.
Published: December 2006

Le mécanisme de dispersion dans l'eau d'une smectite a été étudié en fonction de 2 paramètres: la nature du cation interlamellaire, la nature du feuillet de smectite. Pour cela, on a observé l'évolution du diagramme de diffusion aux petits angles en fonction de la température (entre −15°C et la température ambiante) d'une série de dispersions contenant 20 g d'argile dans 100 g d'eau. La méhode d'interprétation des diagrammes est basée sur la comparaison entre courbes expérimentales et calculées. Les résultats obtenus montrent le rôle, dans l'aptitude au gonflement de la smectite, du cation interlamellaire, de la charge cu feuillet et de sa localisation. Ils montrent également quelles caractéristiques de la structure sont conservées entre la dispersion finale et le solide initial, ce qui permet d'en déduire le mécanisme de dispersion pour chaque smectite.
Cristallochimie des lizardites substituees Mg-Fe-Ni par spectrometrie visible et infrarouge proche
Authors: Cervelle B. D. , Maquet M.
Published: December 2006

Des lizardites substituées (Mg,Fe,Ni)3Si2O5(OH)4 ont été étudiées par spectrométrie en réflectance diffuse de 340 à 2500 nm, de manière à déterminer l'environnement de Mg2+, Ni2+ et Fe2+, en particulier la symétrie des sites et les distances métal-ligands. L'examen de la structure de la lizardite sensu stricto ayant conduit à définir pour Mg2+ deux sites hexacoordonnés M1 et M2 non équivalents dans la couche octaédrique du feuillet serpentineux, l'interprétation, à l'aide de la théorie du champ cristallin, des spectres d'absorption de lizardites de compositions chimiques variées a fourni les résultats suivants: 1. Le site M1 a la symétrie C2v: octaèdre orthorhombique. 2. Le site M2 a la symérie C3v: octaèdre rhomboédrique. 3. Fe2+ est hexacoordonné, et occupe les deux sites M1 et M2 si sa teneur est supérieure à environ 2%. Pour une teneur inférieure, Fe2+ n'occupe que M1. 4. Dans une lizardite Mg + Fe + Ni, Ni2+ est hexacoordonné et occupe le site M2. Ce site du nickel est plus grand en présence de Fe2+, que lorsque le nickel y est seul (népouite). Ni2+ y occupe une position plus rapprochée du centre de la couche octaédrique que Mg2+, ce qui contribue à réduire la flexion du plan des cations dans cette couche. 5. Dans une lizardite proche du pôle nickelifère (népouite), il y a réorganisation de la structure autour d'un site hexacoordonné unique de symétrie C3v. Ce site est déformé, et plus petit: distance moyenne métal-ligand r = 2·06 Å dans la népouite, r = 2·11 Å dans la lizardite magnésienne sensu stricto. Cette réduction de la taille du site ne peut se concevoir que par la réduction de l'épaisseur de la couche octaédrique: 2·20 Å (pôle Mg) à 2·16 Å (pôle Ni).
Etude des echanges entre terres rares et cations interfoliaires de deux argiles
Authors: Bonnot-Courtois C. , Jaffrezic-Renault N.
Published: December 2006

L'étude expérimentale de l'adsorption d'ions La3+ sur une smectite, successivement saturée en ions K+, Na+ puis Ca2+, montre que la stoechiomérie de l'échange s'effectue dans le rapport des charges des cations participant à la réaction. Dans un domaine de force ionique suffisamment restreint, l'échange a lieu dans les rapports suivants: 1 La3+ pour 3 Na+ ou 3 K+, et 1 La3+ pour 1·4 Ca2+. L'adsorption de toutes les terres rares sur la smectite et une illite s'effectue sans ségrégation notable dans cette famille d'éléments, les terres rares les plus lourdes étant un peu plus adsorbées que les terres rares légères. La désorption des terres rares est plus difficile, leur charge trivalente devant les stabiliser en position interfoliaire dans les minéraux argileux.
Etude thermodynamique des echanges d'ions entre gels silicates (A,B)O-SiO2-nH2O et solutions aqueuses (A2+B2+) d'elements de transition
Authors: Perruchot A. , Delbove F.
Published: December 2006

Resume

On étudie les équilibres de distribution de deux éléments de transition divalents A,B, entre gels silicatés inorganiques de formule SiO2-(A,B)O-nH2O et solutions aqueuses A2+,B2+(A.B = Mg, Mn, Ni, Co, Cu, Zn). On montre que l'enthalpie libre molaire standard d'échangede deux éléments A,B entre gel et solution est une fonction linéaire de l'enthalpie libre d'échangecalculée en considérant un échange théorique entre hydroxyde et solution. Les relations obtenues permettent de prévoir le comportement d'autres éléments divalents.
Quelques aspects de l'action des termites du sol sur les argiles
Authors: Boyer Ph.
Published: December 2006

Resume

La majorité des termites sont en rapport avec le sol et utilisent l'argile de ses horizons, pour édiffer leurs termitières. Pour les termites du sol, dont la plupart sont des maçons, l'argile est avant tout le matériau de base offrant les propriétés de rétention d'eau, de plasticité et d'ahésivité, leur permettant de confectionner les mortiers et les microbétons de leurs unités de constructions. Si les termites humivores absorbent toujours une quantité relativement importante d'éléments argileux avec leurs aliments, les termites lignivores n'ingérent qu'occasionnellement une fraction minime d'argile. Leur action sur l'évolution des silicates se traduit par des néoformations de minéraux argileux au sein de leurs constructions: illite ‘artificielle’, hydrobiotite, vermiculite, halloysite, montmorillonite, et parfoils sépiolite et attapulgite. Ces néoformations résultent de l'action conjugée du travail de broyage et de trituration salivaire de minéraux encore peu altérés de la profondeur du sol, et des conditions physico-chimiques de milieu particulières aux termites.
Crystallization of Fe(III)-Oxides from ferrihydrite in salt solutions: osmotic and specific ion effects
Authors: Torrent J. , Guzman R.
Published: December 2006

Ferrihydrite transformed to crystalline Fe(III)-oxides in salt solutions but the degree of transformation generally decreased with increasing concentration (decreasing water activity) and haematite was favoured over goethite. More transformation occurred for chloride than for nitrate or sulphate and more for calcium than for magnesium or sodium. Calcium and magnesium favoured haematite over goethite. The results support the hypothesis that haematite not only can be formed but will be favoured over goethite in natural environments with low water activity, for instance dry or saline soils or sediments. The ionic environment modifies the general water activity effect.
Determination of the oxidation state of manganese in lepidolite by X-ray photoelectron spectroscopy
Authors: Evans S. , Raftery E.
Published: December 2006

It is usually assumed that the oxidation state of the small proportion of Mn sometimes present in micas is +2, although there is evidence from electronic spectroscopy (Burns, 1970) for at least the occasional occurrence of Mn(III) in manganophyllite. We describe here X-ray photoelectron spectroscopic (XPS) measurements on the Mn in a Norwegian lepidolite which was the subject of a concurrent structural study by X-ray photoelectron diffraction (Evans & Raftery, 1982). To establish the Mn oxidation state we have compared the Mn2p core-electron binding energies (BE), the Mn2P3/2-O ls BE differences, and the Mn2p XPS peak profiles from the four common oxides of manganese (MnO, Mn3O4, Mn2O3 and MnO2) with those from the lepidolite. A re-examination of these oxides was undertaken because the agreement between reports in the literature was unsatisfactory, and uncertainty existed concerning the integrity of some of the surfaces previously examined.
Relationships between chemical, physical and mineralogical characteristics of the Rupelian Boom Clay, Belgium
Authors: Decleer J. , Viaene W. , Vandenberghe N.
Published: December 2006

The Boom Clay is an important raw material for the Belgian structural clay products industry. It can be divided into several lithological sub-units. In order to obtain an insight in the parameters which characterize these different units, and which affect the overall properties of the clay, a detailed chemical, physical and mineralogical analysis was carried out. Pearson correlation coefficients were calculated between the variables, which were then placed in four correlation groups: a quartz/clay mineral group, a reducing component group, a carbonate group and a feldspar group. This treatment of the data allowed three analysis parameters to be selected: <2 µm fraction, organic carbon and CO2. The other variables could be calculated fairly accurately from these by means of regression lines.
Clay minerals as indicators of wind and current contribution to post-glacial sedimentation on the Azores/Iceland Ridge
Authors: Grousset F. , Latouche C. , Maillet N.
Published: December 2006

Clay mineral and trace element data indicate that sediments in the vicinity of the North Mid-Atlantic Ridge derive from material of both Icelandic and Canadian origin. These sources agree with the marine and atmospheric circulation patterns observed in this area.
Tarasovite, a mixed-layer illite-smectite which approaches an ordered 3:1 layer ratio
Authors: Brindley G. W. , Suzuki Tetsuya
Published: December 2006

Basal X-ray peaks from normal and ethylene glycol-saturated tarasovite have been measured to 0.0.36 and 0.0.38, respectively; the mean basal spacings were 43·73 ± 0·44 and 46·05 ± 0·33 Å, withCVvalues of 1·31 and 0·97. The spacings indicate a near approach to a 3 : 1 illite-smectite but theCVvalues indicate a greater variability than is normally consistent with the allocation of a special name. Comparison of the observed spacings with those for illite showed that the more deviant values were always adjacent to positions of illite reflections. A modified Mering treatment of diffraction by mixed-layer sequences was used to estimate the proportion of illite layers; the average result was 79·9 ± 2·0%. The mineral is considered to have 3 : 1 illite-smectite units with randomly added illite layers, bringing the ratio from 75% for the ideally ordered sequence to near 80%.
Origin of bauxite at Eufaula, Alabama, USA
Authors: Lukas T. C. , Loughnan F. C. , Eades J. L.
Published: December 2006

An autochthonous origin for the bauxite deposits of the Eufaula district, south-eastern Alabama, appears to have received general acceptance but, compared with younger residual bauxites of the present day tropical regions of the world, the Eufaula deposits have a number of features that are difficult to reconcile with development in situ. In an attempt to resolve the enigma, a detailed study was undertaken of cores from three drill holes that intersected a complete succession through one of the Eufaula deposits. Although the results are not conclusive, it is believed that much of the observed phenomena can be explained on the basis of an essentially transported origin for the deposits.
Relationships between composition and structure in Fe-rich smectites
Authors: Brigatti Maria Franca
Published: December 2006

Chemical and crystallochemical properties of natural dioctahedral Fe-rich smectites formed by weathering of basaltic rocks in the Berici-Euganei Area, northern Italy, were investigated. It was found that: (i) the b-dimension could be correlated both to Fe3+/Σ ratio (Σ = octahedral occupancy) and to dehydroxylation peak temperature in the range 400–600°C; (ii) it is not correct to impose a total octahedral occupancy strictly equal to 2 for dioctahedral smectites; (iii) in the smectite group there is not a continuous isomorphous series as would appear on the basis of chemical features only.
NMR applied to minerals: IV. Local order in the octahedral sheet of micas: Fe-F avoidance
Authors: Sanz J. , Stone W. E. E.
Published: December 2006

A series of phlogopite and biotite samples were examined by wide-line NMR spectroscopy. Monitoring of the fluorine signal revealed the presence of homogeneous fluorine domains. The importance of these domains increased with increase in F and Fe contents. A model for the distribution of anions and cations in the octahedral sheet of micas is presented and discussed.
Water sorption on Ca-saturated clays: II. Internal and external surfaces of montmorillonite
Authors: Ormerod E. C. , Newman A. C. D.
Published: December 2006

Water-sorption isotherms and interlamellar spacings were measured for Ca montmorillonite (from Redhill. UK) over the relative pressure range 1 >P/P0> 0. By taking account of the change in interlamellar volume with relative pressure, it is shown that internal and external surfaces can be calculated by a modifiedt-plot analysis. The results also show that sorption on the external surfaces of the montmorillonite is quantitatively similar to that on reference oxide surfaces. Desorption-sorption hysteresis occurred and was apparently caused by an ageing process in which the interlamellar volume increased at the expense of the external surfaces.
The properties and uses of clays which swell in organic solvents
Authors: Jones T. R.
Published: December 2006

The exchangable cations present on certain montmorillonites can be replaced by long-chain quarternary ammonium cations, and the resulting clays have the important property of being able to swell and disperse in a variety of organic solvents. Organophilic clays have a wide range of industrial applications and are, for example, important constituents of oil-well drilling fluids, paints, plastics and greases; their role in these is discussed. Organophilic clays have been extensively studied for about 50 years, but neither the structure nor the mechanisms by which they swell and disperse in organic solvents are clearly understood. An attempt is made to interpret the industrial applicatons in terms of published ideas concerning the structure and swelling properties of organophilic clays.
Montmorillonite catalysts for ethylene hydration
Authors: Atkins M. P. , Smith D. J. H. , Westlake D. J.
Published: December 2006

Ion-exchanged montmorillonites behave as solid acid catalysts and are effective and selective catalysts for the hydration of ethylene. The reaction proceeds predominantly in the interlamellar environment of the clay catalyst. Ethylene conversions were found to be markedly dependent on the choice of exchangeable cation, with Al being the best of those examined.
The production of ethyl acetate from ethylene and acetic acid using clay catalysts
Authors: Gregory R. , Smith D. J. H. , Westlake D. J.
Published: December 2006

Wyoming bentonite, exchanged with cations of high charge density, is an efficient and selective catalyst for the production of ethyl acetate, in a single step, from ethylene and acetic acid. The reaction occurs in the interlamellar space of the clay where it is proposed that strong Brönsted acid sites on the clay coupled with highly polarized intercalated reactants produce a reaction which is otherwise difficult to carry out.
Some organic syntheses with clay-supported reagents
Authors: Cornelis A. , Laszlo P. , Pennetreau P.
Published: December 2006

Some uses of clay-supported reagents in fine organic synthesis are discussed, in particular the catalysis of the phase-transfer preparation of formaldehyde acetals by quaternary ammonium montmorillonites. The preparation and some applications of clay-supported ferric nitrate, a new reagent which oxidizes alcohols into carbonyl derivatives, couples thiols into disulphides, nitrates phenols, and oxidatively couples pyrrole and benzaldehyde into tetra-phenylporphyrin, are also described
Microanalyses geochimiques de mineraux argileux de sediments preleves et Atlantique Nord (Forages du DSDP)
Authors: Debrabant P. , Delbart S. , Lemaguer D.
Published: December 2006

Resume

L'analyse semi-quantitative, avec une microsonde électronique CAMEBAX, met en évidence des variations chimiques significatives dans des assemblages simples de minéraux argileux. La méthode est décrite et deux applications sont présentées et interprétées en termes de genèse et de paléoenvironnement. La microgéochimie d'illites et de chlorites du Crétacé inférieur (Marge du Maroc) évolue vers le haut de la série (diminution du magnésium) et semble influencée par une diagenèse salifère transformant des argiles détritiques. Des chlorites hypermagnésiennes apparaissent dans les sédiments les plus profonds, et autorisent l'hypothèse d'une authigenèse en milieu confiné. Les différentes smectites étudiées a la limite basalte-sédiment des sites 105 et 384 du DSDP (NW Atlantique) peuvent aisément être distinguées par leur microgéochimie avec Mg, Na, K, Al, Fe, Ti. Elles reflètent diverses sources volcaniques et leurs caractères sont très différents de ceux des smectites terrigènes communes.
X-ray powder transmission diffractometry determination of mica polytypes: method and application to natural samples
Authors: Wiewióra A. , Weiss Z.
Published: December 2006

Transmission powder patterns of random and of highly oriented samples of natural micas have been recorded and compared with those calculated from structural data with the aid of the DIFK computer program modified to correct for preferred orientation. Intensities calculated from structural data for random and for highly oriented samples (symmetrical and oblique settings) are presented for 1M, 2M1, 2M2, 3T polytypes of muscovite, 1M, 2M1, 3T polytypes of paragonite and 1M (C2/m and C2 space groups), 2M1, 2M2, 3T polytypes of lepidolite.
An X-ray analysis of stacking disorder in kaolinite by fourth moment
Authors: De A. K. , Bhattacherjee S.
Published: December 2006

Mathematically, it is well established that besides the Fourier coefficients, the natural characteristics of any distribution are its moments. The use of the second moment, called variance, as a measure of line broadening has already gained wide popularity because of its several merits relative to other empirically devised parameters. In recent decades, the fourth moment has been recognized as an important parameter; its theoretical significance has been discussed by Mitra (1964), who developed the moment range function for the estimation of crystallite size and distortion in cold-worked metal. However, owing to the requirements of high degree of accuracy of intensity measurement coupled with cumbersome calculations, this parameter did not find much general application. Modern diffractometers and sophisticated computers have helped ease the problem and in recent years several workers (Kagan & Snovidov, 1965; Kulshreshtha et al., 1971; Mukherjee, 1981) have successfully used this parameter for defect analysis in various non-ideal forms of materials.
Origin and evolution of smectites in Recent marine sediments of the NE Atlantic
Authors: Parra M. , Delmont P. , Ferragne A. , Latouche C. , Pons J. C. , Puechmaille C.
Published: December 2006

Present-day marine sediments around the emerged basaltic areas of Iceland and the Faeroe Islands are characterized by the abundance and predominance of smectites. Smectites increase regularly and systematically near volcanic areas. Their origin from (i) meteoric/deuteric weathering, (ii) hydrothermal products, (iii) neoformation in the marine environment or (iv) transformation during their transport to or stay in oceanic regions is considered in a comparative study of three types of environments on or near the Faeroe Islands. These are (1) a basaltic environment where phyllite minerals of deuteric and hydrothermal origin are abundant; (2) a soil environment formed on basaltic flows; (3) a marine sedimentary environment within adjacent sedimentary basins. This investigation clearly shows the link between hydrothermal and deuteric saponite-celadonite in basalt, Fe,Mg-smectite in Faeroe soils and Fe-smectite in marine sediments.
Additional notes on Wood-tin
Authors: Collins J. H.
Published: December 2006

In my previous papers I described and illustrated several examples of the concentrically banded and radiated varieties of cassiterite known as ‘wood-tin’, and stated that one very constant character of this variety was its rather remarkable opacity as compared with ordinary cassiterite, which is indeed somewhat exceptionally transparent considering its (often) deep coloration. I also noted the frequent occurrence of specimens of wood-tin encrusted with more or less distinct crystals of cassiterite, or traversed by fissures filled with such crystals, as indicating successive formation.
The larger Diamonds of South Africa
Authors: Spencer L. J.
Published: December 2006

The inquiry that I have recently made into the weight of the ‘Cullinau’ diamond has led me to clear up, as far as possible, various discrepancies in the published statements respecting the other large diamonds of South Africa. Although a knowledge of the exact weights of these stones is a matter of only trivial scientific importance, yet it is desirable to place on record any definite facts that may still be gathered respecting them. Much valuable information in this direction has been freely given to me by Messrs. Wernher, Beit & Co., through whose hands several of the larger stones have passed ; without their help the present notes could not have been written, and I therefore desire to express to them my hearty thanks.
Crystallographic notes on Inosite, Potassium nitrate, and Urea nitrate
Authors: Barker Thomas Vipond
Published: December 2006

Crystals of Inosite, C6H6(OH)6.2H2O , were first measured by Cloёtta, and somewhat later by Zepharovieh, and by Lewis; they are monoclinic, and the elements adopted are those of Zepharovieh, viz., a : b : c = 1.0872 : 1 : 1.5602 ; β = 111° 39′. The observed forms on the crystals were {010}, {110}, {100}, {001}, , , {210}, and {410}, and it is seen that the form-development is of a somewhat anomalous character, the indices of the last three forms being remarkable for their complexity.
On Sericite from North Wales and on Penninite and Labradorite from Ireland
Authors: Hutchinson A. , Campbell Smith W.
Published: December 2006

For the first of the three minerals to be described in the following pages we are indebted to Mr. W. G. Fearnsides, who collected it in North Wales in the autumn of 1908, and we desire to express our best thanks to him for the readiness with which he placed at our disposal enough suitable material for a complete analysis. The other two minerals were collected by ourselves.
On Topaz and Beryl from the granite of Lundy Island
Authors: McLintock W. F. P. , Hall T. C. F.
Published: December 2006

Although topaz and beryl have been previously recorded from Lundy Island, no account has hitherto been published of their characters and mode of occurrence. In the summer of last year a geological survey of the Island was commenced by one of us, and during the progress of the work good crystals of these minerals were obtained, the results of an examination of which it seems desirable to place before this Society.
Ilmenite from the dolomite at Binn, Switzerland
Authors: Lewis W. J.
Published: December 2006

As is well known, the dolomite of the Lengenbach quarry is rich in pyrites and has some rutile.; the crystals of the latter being very small and somewhat infrequent. It seems therefore strange that the presence of hematite or ilmenite has not hitherto been recorded. This last summer I obtained a specimen which showed a minute black crystal with numerous faces, which I began examining under the impression that it was a sulpharsenite.
Augite from Bail Hill, Dumfriesshire
Authors: Scott Alexander
Published: December 2006

The crystals to which this paper refers are found at Bail Hill, about three miles north of Sanquhar, in Dumfriesshire. At this locality volcanic rocks of Arenlg age outcrop in the midst of the greywacke of the Southern Uplands. The rocks are mainly lavas, and include some coarse-grained tufts which are composed chiefly of augite- and hornblendeandesites. Ill the andesitic fragments, there arc numerous porphyritic crystals of a black augite, which call be easily separated from the rest of the rock. Isolated crystals of augite and hornblende occur also in the matrix of the tufts. No mention of this occurrence is made in Heddle's 'Mineralogy of Scotland', and apparently the only reference to it in previous literature is the short petrographic description in the Geological Survey Memoir.
Note on the pleochroism of Adamite
Authors: Spencer L. J.
Published: December 2006

The mineral adamite (Zns(AsO4)2.Zn(OH)2), discovered by C. Friedel in 1866 on specimens from Chafiarcillo, Chile, has since been found at only two other localities, namely Cape Garonne in France and Laurion in Greece. At the original locality it would appear to be of rare occurrence, since in the literature mention is made of only two specimens.

It was therefore of interest to find in the British Museum collection a good specimen of adamite from Chafiarcillo. This was found amongst the hornsilvers, and the associated adamite had been thought to be fluorite, which indeed, at first glance, with its violet colour and good cleavage, it closely resembles in appearance. The crystals are remarkable by reason of their very strong pleochroism, and as this feature of adamite has previously received no mention it has been thought worthy of placing on record.
Formule générale donnant la biréfringence d'une lame cristalline en fonction des angles que sa normale fait avec les axes d'élasticité optique. La formule approximative habituelle s'obtient en y supposant les indices infinis, tout en conservant entre eux les différences finies qui existent en réalité
Authors: Cesàro G.
Published: December 2006

Dans les questions relatives aux biréfringences on emploie des formules approximatives, et je ne trouve relatde nulle part la formule dormant exactement la biréfringenee d'une face en fonction des angles que sa normale fair avec les axes d'éasticitd optique. Le but de cette note est d'indiquer cette formule, d'ailleurs très simple, et surtout de montrer clue la formule approximative habituelle se déduit de la formule exacte en y supposant l'indice moyen infini.
The Natrolite occurrence near Kinbane (White Head), County Antrim
Authors: Ashcroft F. N.
Published: December 2006

It is impossible to determine when this natrolite occurrence was first discovered, but it has been known at any race locally for many years, and specimens of the mineral may frequently be seen in collections, where, however, they are usually labelled as from the Giant's Causeway. This error in localization is largely accounted tbr by the fact that the guides at the Giant's Causeway regularly offer specimens of the mineral for sale to visitors, together with other so-called Giant's Causeway minerals, fossils, and flint implements.
A butterfly-twin of Gypsum
Authors: Spencer L. J.
Published: December 2006

The specimen here described was acquired in 1913 for the mineral collection of the British Museum. It came from one of the numerous sulphur mines in the province of Girgenti, Sicily. Being of some size (15 cm. = 6 inches across) and with the two individuals well separated and symmetrically disposed, it affords a striking illustration of a twin growth. The crystal is colourless and perfectly transparent; it encloses one or two small patches of native sulphur and compact limestone. A portion, probably about one-third, of the original specimen has been broken away along the perfect cleavage of gypsum ; and this fact, together with the amall point of attachment, increases the resemblance of the twin to tbe butterfly form, which is here more striking than in the so-called butterfly-twins of calcite.
Lattice-like inclusions in Calcite from North Burgess, Ontario
Authors: Graham R. P. D.
Published: December 2006

The pale celestite-blue calcite which occurs on the eastern half of Lot 13, Range V, of North Burgess township, Lanark county, Ontario, contains very remarkable lattice-like inclusions of a hydrous magnesium silicate.

The calcite forms crystalline masses belonging to the Grenville series, which has a very extensive areal development in certain parts of Ontario. The texture varies from medium to very coarse, in which the individual cleavage-rhombs of calcite measure one inch or more in diameter. Repeated twinning on e (0112) or (101) is almost invariably exhibited, and is especially pronounced in the more coarsely crystallized varietiea Both the twinning and the crystalline character are results of the very intense metamorphism to which this Archaean limestone has been subjected.
On the origin of septarian structure
Authors: Alfred Richardson W.
Published: December 2006

In the Geological Magazine for 1918 there appeared three papers discussing the origin of tile system of cracks ill septarian nodules. Dr. A. Morley Davies opened the discussion in a paper where, after a summary of earlier literature, he again put forward an older idea. Without adducing evidence, he considered :

(a)

that interposition of particles between those of the original matrix caused expansion which set up tensile strain in the growing body ;

(b)

that the cracking of the nodule was due to the relief of those tensile
stresses.
A new mineral, isomorphous with trechmannite, from the Binn valley, Switzerland
Authors: Solly R. H.
Published: December 2006

In August 1904 I discovered in the Lengeubach quarry a specimen on which were three small, round-shaped crystals, about the size of small shot, grown upon a prismatic crystal of sartorite. I measured them, and owing to their small size experienced some difficulty in determining the position of some of the faces with the goniometer at my disposal, which was of the ordinary single-circle pattern.
Curvature in Crystals
Authors: Spencer L. J.
Published: December 2006

The following notes were prepared at the request of Dr. J. E. Stead, F.R.S., the well-known metallographer. Several years ago he had obtained in a tin-antimony-arsenic alloy some remarkable crystals having the form of seganents of spherical shells (fig. 3, p. 9.72 below), and he naturally wished to learn if anything of the same kind was known amongst minerals. The notes contain no new data, but merely collect together facts already known to mineralogists. They may perhaps be of some use to metallographers in calling attention to the various habits of growth met with amongst minerals, since distortions and irregularities of crystalline growth are so frequent amongst metals.
The frequency-distribution of igneous rocks. I. Frequency-distribution of the major oxides in analyses of igneous rocks
Authors: Alferd Richardson W. , Sneesby G.
Published: December 2006

The quantitative distribution of igneous rocks has recently assumed a place of importance in petrogenic discussions. This is due largely to the influence of Daly, who made a survey of the areal distribution of rock types as shown by their outcrops on published maps, and reached the well-known conclusion that intrusions are overwhelmingly granitic in composition, and that extrusions arc largely basaltic. If further research should firmly establish this result, it will unquestionably be a fact of the first order of importance of which any general theory of petrogenesis must take cognizance.
Relation of the crystal-structure of some carbon compounds to those of graphite and diamond
Authors: Bragg William H.
Published: December 2006

It must be our aim to correlate the external appearance of a crystal, and its physical properties also, with the arrangement of the atoms inside and the forces that join the atoms together. We might hope to gain so much knowledge on these points that, given a certain set of atoms, it would become possible to anticipate the design of their arrangement and to describe all the characteristics of the crystalline substance as consequences. The analysis of crystals by means of X-rays has given us a little help along this road, and we begin to see certain principles in broad outline.