bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Intercalation of Polar Organic Compounds into Kaolinite
Authors: Olejnik S. , Posner A. M. , Quirk J. P. 
Published: December 2006

AbstractThe intercalation of several highly polar organic compounds into kaolinite and the formation of interlamellar complexes has been examined by X-ray diffraction. Some compounds intercalate directly into kaolinite, while others can only be intercalated by the displacement of a previously intercalated compound. The formation of the complexes is strongly dependent on the properties of the organic compound, and generally a large dipole moment favours the formation of a complex. A large dipole moment may however cause extensive association in the liquid state and this decreases the rate of intercalation. The addition of water to highly associated compounds increases the rate of intercalation by breaking up the structure of the associated liquid, and the rate passes through a maximum with increasing water content. Thus the rate of intercalation is found to depend on the extent of association in the liquid or solution, the temperature and the molecular size. The d(001) spacings of the complexes are given and the orientation and packing of the intercalated molecules in relation to the Δ - values is discussed.
A Study of Weathering in a Soil Derived from a Biotite-Hornblende Rock
Authors: Wilson M. J. , Farmer V. C. 
Published: December 2006

AbstractThe weathering of hornblende in the Rehiran profile has been investigated by optical, X-ray, infrared and differential thermal methods. Optical studies of the fresh hornblende show that it contains discrete lamellar intergrowths of another amphibole which, from infrared evidence, is of an iron-rich nature. This minor phase is selectively weathered in the lower horizons and yields a clay mineral which was identified as interstratified swelling chlorite-saponite. The major hornblende component remains relatively unchanged. Single crystal photographs indicate that the formation of the clay mineral is not structurally controlled by the parent hornblende, although there is a tendency towards alignment along cleavage planes. The clay mineral becomes unstable in the upper part of the profile and could not be detected in the A horizon. Comparisons are made with the findings of other workers.
A plasticity chart as an aid to the identification and assessment of industrial clays
Authors: Bain J. A. 
Published: December 2006

AbstractThe plastic properties of clays are sufficiently variable to offer a simple but practical aid to identification. This can be done by using their Atterberg 'plastic limit' and 'plasticity index' values as parameters for an identification chart. The advantages and disadvantages of the technique are discussed, and results for a wide variety of clay minerals, particularly industrial clay types, are illustrated. A brief summary is also given of the effect of non-clay impurities, and reference is made to the correlation of Atterberg limit values with other physical properties of clays.
Some applications of thermohygrometric analysis to the study of clay and associated minerals
Authors: Creer M. H. , Hardy J. B. C. , Rooksby H. P. , Still J. E. 
Published: December 2006

AbstractA new method of measuring the water evolved on thermal dehydration of a variety of clay minerals and related hydrated compounds is described. By placing the substance in a tubular furnace and passing over it a dry inert gas, water released on heating is carried to a sensitive electrolytic hygrometer for measurement. The heating is programmed to give a uniform rate of temperature rise, so that continuous monitoring of the evolved water permits discrimination between successive dehydration processes occurring at different temperatures. The procedure is appropriately termed thermohygrometric analysis (THA).The applications described include investigations of the thermal decomposition behaviours of hydrated aluminas and hydrated iron oxides, and of clay minerals such as kaolin, montmorillonite, chrysotile and micas. The relations between the results given by thermohygrometric analysis and those obtained by differential thermal analysis are discussed. As with DTA, the record trace from a THA examination gives a graphical representation of the dehydration process, but THA has an advantage in providing a quantitative measurement of the water evolved.
The correspondence between optical and X-ray measurements of particle orientation in clays
Authors: Tchalenko J. S. , Burnett A. D. , Hung J. J. 
Published: December 2006

AbstractThe spatial arrangement of platy particles in a clay is defined by an orientation ratio which can be derived analytically from optical birefringence as well as from X-ray diffraction data. Measurements on kaolin slurries consolidated by increasing loads were used to verify that orientation ratios obtained experimentally by these two methods are in fact equivalent. In contrast it was found that particle orientation cannot be assessed objectively from electronmicrographs alone. A combined optical-X-ray study of two natural clays (London Clay and Lias Clay) revealed that the kaolinite crystals are oriented only slightly more than the illite crystals, and showed that the correspondence between optical and X-ray measurements is also valid for natural clays.
A study of disorder in kaolinite
Authors: Noble F. R. 
Published: December 2006

AbstractX-ray powder diffraction patterns of kaolinites have been studied with especial reference to the region of the 02, 11, band. Satisfactory correlations with calculated patterns based on the layer structure of dickite can be achieved for a range of kaolinites if account is taken of disorder between and within layers. Some indication of the amount of disorder within a kaolinite can be obtained.
Pyrophyllite-bearing flint clay from the Cambewarra area, New South Wales
Authors: Loughnan F. C. , Ward C. R. 
Published: December 2006

AbstractA thick deposit of flint clay in the Permian I llawarra Coal Measures of the southern part of the Sydney Basin, New South Wales, is described. The flint clays which have affinities with those of the Pennsylvanian of North America and with the kaolin coal tonsteins of the Westphalian, are associated with red-brown claystones that contain in addition to hematite, an abundance of a regular mixed layer clay mineral. Pyrophyllite generally forms a minor constituent only of the flint clays but in one part of the deposit it is more abundant than kaolinite. Although there are many puzzling aspects concerning the origin of the deposit, evidence suggests that the kaolinite and the pyrophyllite in the flint clays are detrital.
Beidellitic montmorillonite from Swansea, New South Wales
Authors: Hamilton J. D. 
Published: December 2006

AbstractThe minus 1μm fraction of an argillized vitric tuff, overlying the Wallarah Coal Seam near Swansea, N.S.W. is a nearly monomineralic (95%+) expandite clay, which hydrates and reacts to glycerol and heat treatments like montmorillonite. Results of X-ray, differential thermal, thermogravimetric and infrared absorption analyses confirm the general montmorillonoid character of the mineral, but chemical data indicate that much of its structure charge arises from substitutions in the tetrahedral zones of the lattice, as in beidellite rather than montmorillonite. The structural fOrmula deduced for the Ca++-saturated form of the minus 0.1μm clay is:The distinctive behaviours of the heat-treated NH4+- and Li+-saturated structures also suggest that the mineral is a 'beidellitic montmorillonite' rather than a montmorillonite.
Complexes vermiculite—aminoacides
Authors: Rausell-Colom J. A. , Salvador P. S. 
Published: December 2006

AbstractVermiculite single crystals immersed in aminoacid solutions of varying concentration and pH, form complexes characterized by discrete basal spacings. Organic molecules enter in the interlayer space as cations and as dipolar ions through mechanisms of ion exchange and dipole adsorption.The basal spacings of the complexes were recorded. Based on these results the possible arrangements of the aminoacid molecules have been discussed.The main assumptions used are: (a) the electropositive groups NH3+penetrate into the holes formed by the basal oxygens of the silicate; (13) the C-N bonds are perpendicular to the silicate sheets; (c) the hydrogen atoms of the —CH2 groups are directed towards the sheet surfaces; (d) the —COO−and —COOH groups are located in the middle plane of the interlayer space, halfway between the negative structural charges; and (e) double hydrogen bonds are formed between —COOH groups belonging to organic cations adsorbed onto opposite surfaces.In solutions of higher concentration the crystals swell to the gel state. This phenomenon is due to: (a) the different nature of interlayer cohesion after substitution of the inorganic cations by the aminoacid cationic form; and (b) the appearance of repulsive forces between —COO−groups of adsorbed dipoles, that overcome cohesive forces.
Complexes of halloysite with organic compounds
Authors: Carr R. M. , Chih Hwa 
Published: December 2006

AbstractMore than twenty new organic complexes of halloysite have been prepared and one hundred and twenty-seven compounds were tested. Results are compared with those of earlier studies and use is made of recent findings concerning particle morphology and interstratification effects to interpret the results. The compounds which form complexes with halloysite are polar, and are usually either acids or bases. Their molecules usually contain two functional groups (preferably —OH and/or —NH2), are relatively small and have one functional group per two carbon atoms, but do not usually include cyclic or aromatic types. The best explanation of the existence of these metastable complexes seems to lie in the ability of some organic molecules to form hydrogen bonds with the halloysite structure, about which insufficient knowledge is available to allow quantitative evaluations to be made.
Partial molal volumes of calcium-montmorillonite
Authors: Ferreiro E. A. , Helmy A. K. 
Published: December 2006

AbstractPartial molal voltmae of Ca-montmorillonite, apparent molal volume of silica gel in water and of Ca-montmorillonite in ethanol-water mixtures, were determined using pycnometer density measurements. No electrostriction of water was observed with silica gel but took place in Ca-montmorillonite thus indicating the principle role of surface charges in stricting water. In ethanol-water mixtures alcohol molecules were salted out at low alcohol concentration, but they started reaching inner zones near the clay surfaces when their mole fraction in solution was increased beyond the value of 0·55.
The apparent and partial molal volumes of K-montmorillonite
Authors: Ferreiro E. A. , Helmy A. K. 
Published: December 2006

AbstractThe partial and apparent molal volumes of K-bentonite in pure water and in 0·5 M KCl were determined using pycnometer density data. The values obtained were found to increase with particle concentration. Theoretical values of the electrostatic contribution to the volume of particles calculated from an assumed model based on the electric double layer theory, gave values different from those found experimentally. This is explained as due largely to the uncertainties in the value of the clay specific surface area as well as to the assumed ideality of the model used.
Calculated X-ray diffraction profiles for interstratified kaolinite-montmorillonite
Authors: Cradwick P. D. , Wilson M. J. 
Published: December 2006

AbstractCalculated diffraction profiles for interstratified kaolinite and montmorillonite have been used to determine the composition of clays reported from Poland, Japan and Mexico. The predicted layer proportions determined from the curves and by other methods are in close agreement for the first two but a higher kaolinite content than that originally proposed is obtained for the Mexican clays.
Some problems encountered in the identification of plumbogummite minerals in soils
Authors: Campbell A. S. , Adams J. A. , Howarth D. T. 
Published: December 2006

AbstractThe use of HF digestion to concentrate minerals of the plumbogummite group is discussed. Prolonged treatment is shown to result in solution of plumbogummite minerals, and in precipitation of HCl-insoluble, complex fluorides. These yield X-ray diffraction spacings that may be confused with those of plumbogummite minerals. The presence of fluorides in digestion residues is confirmed by X-ray diffraction, DTA and by identifying the products formed when such residues are heated to 600°C.
An Electron Microscope Study of Magnesium Smectite Synthesis
Authors: Baird T. , Cairns-Smith A. G. , Mackenzie D. W. 
Published: December 2006

AbstractThe synthesis of magnesium smectite from heated slurries of magnesium hydroxide, silica and lithium fluoride proceeds through ready formation of torroidal structures visible under the electron microscope. These are associated with the synthesis of a smectite-like material with, however, only half the expected requirement for silica. True smectite only forms significantly with Si/Mg ratios > 1 and reaction times (at reflux) > 1-3 days.
A Rapid Method for the Determination of Quartz in Sedimentary Rocks by X-Ray Diffraction Incorporating Mass Absorption Correction
Authors: Cosgrove M. E. , Sulaiman A. M. A. 
Published: December 2006

AbstractAn X-ray diffraction method for the estimation of quartz is described using rock powder pellets originally prepared for X-ray spectrometry, correcting the X-ray intensities for mass absorption. A coefficient of variation of 3·8% is claimed; 95% of all estimates fall within ± 5·5%.
An Unusual Chlorite as Revealed by the High Temperature X-Ray Diffractometer
Authors: Kimbara K. , Shimoda S. , Sudo T. 
Published: December 2006

AbstractAn unusual chlorite has been collected from amygdales in Miocene volcanic rock found at Taiheizan, Akita Prefecture, Japan. The mineral shows subtle variations from other chlorites and related minerals. These are: (a) no apparent expansion with water or ethylene glycol, (b) negligible or no collapse after NH4-saturation or heating at about 300°C, (c) a slow decrease in the basal spacing on heating from approximately 400°C to 760°C, (d) a small amount of low temperature or capillary water and (e) a DTA curve with a vermiculite-like system of peaks.The mineral is identified as a highly chloritic vermiculite with a small proportion of imperfect hydroxy interlayer.
An interstratified illite-smectite from Denchworth series soil in weathered Oxford Clay
Authors: Weir A. H. , Rayner J. H. 
Published: December 2006

AbstractThe very fine (<0·04 µm) clay fraction of a Denchworth series subsoil in weathered Oxford Clay has been investigated in detail. It contains a layer silicate mineral, almost free from impurities, that is a randomly interstratified mixture of approximately 45% expanding and 55% non-expanding interlayers with the following unit formula: Na0.33K0.29(Al1.41Fe0.34Mg0.26)(Si3.60Al0.40)O11. Computer-simulated diffraction patterns showed that experimental patterns are best matched when an average diffracting packet consists of between 4 and 5 2:1 layer silicate units. Correction of the chemical composition for external exchangeable ions associated with such small packets gives non-expanding interlayers a charge density of 0·69K/Si4O11 and expanding interlayers one of 0·57M+/Si4O11. The relationship between these values and those of mica and regularly expanding minerals is briefly discussed.
Flocculation of Na-montmorillonite by electrolytes
Authors: Ferreiro E. A. , Helmy A. K. 
Published: December 2006

AbstractThe flocculation of a Na-montmorillonite suspension by Na, Ca, and Al chlorides was investigated using the optical absorbance method. The flocculation of the clay was found to be irreversible with a degree of irreversibility that increases with electrolyte concentration. The flocculation values of Na, Ca and Al chlorides were found to be equal to 8, 0·25 and 0·032 mmol/l respectively. The ratio of the flocculation values of the different salts is in reasonable agreement with the ratio predicted by current theories of colloid stability.
The point of zero charge (pzc) of kaolinite and SiO2+AI2O3 mixtures
Authors: Tschapek M. , Tcheichvili L. , Wasowski C. 
Published: December 2006

AbstractThe pzc of H+-kaolins determined by titration method is nearly pH = 3. The pzc of SiO2 + Al2O3 mixtures is not additive, and depends principally on Al2O3 content in mixture. The curve pzc—t°C (t°C = temperature of treatment of kaolins) has two maxima: 4·7 after treatment at 800-900°C, and 5 after treatment at 1300°C.
Selective dissolution and formula derivation of clay vermiculite from some Tuscan soils
Authors: Ristori G. G. , Cecconi S. , Vidrich V. , Pacifici G. 
Published: December 2006

AbstractThe chemical composition and structural characteristics of clays from samples of eight Tuscan soils were investigated. Using simple selective dissolution method (successive boiling in 1 N HCl and 0·5 N NaOH) it was possible to distinguish two types of low charge dioctahedral vermiculite; one easily HCl soluble the other practically insoluble.Structural formulae for the soluble type were calculated from the chemical analysis of the dissolved material; for the insoluble type it was possible to calculate only an 'average' structural formula which included the micaceous material.Since the HCl soluble vermiculites show a high content of Fe and Mg, they can be considered either as alteration products of glauconites or biotites, or as a result of a synthesis, at least in soils derived from basic rocks which do not contain mica.The aluminous insoluble type, present also in parent material, may be the result of an incomplete 'illitization' in a marine environment.
Maghemite in soils and its origin
Authors: Taylor R. M. , Schwertmann U. 
Published: December 2006

AbstractA magnetic iron oxide is a common constituent of ferruginous concretions in highly weathered Australian soils and is generally associated with varying proportions of hematite and occasionally with goethite. The X-ray diffraction pattern and the low Fe (11) contents (4-15% of total Fe) of this magnetic phase identify it as maghemite which was further confirmed by IR and DTA. This maghemite is only slightly soluble in dithionite but readily in 1:1 HCl or oxalic acid. From the Fe (11) contents and mineralogical associations in soil concretions, conditions for maghemite formation under near pedogenic conditions are suggested.
Electron spin resonance in natural kaolinites containing Fe3+ and other transition metal ions
Authors: Meads R. E. , Malden P. J. 
Published: December 2006

AbstractA number of natural kaolinites from a variety of world sources have been investigated using electron spin resonance at both X-band and Q-band. The results show systematic differences some of which are related to the crystallinity of the material, some to the presence of transition metal ions other than Fe3+ and hole-trapping defects.The results provide evidence for at least three sites for substitution of Fe3+ having large crystal fields : (i) a site with near maximum rhombic character having crystal field parameters D > 1·2, λ = ⅓ the occurrence of which is correlated with lack of crystalline perfection due to stacking defects or to the proximity of surfaces, (ii) a site with less rhombic character with λ = 0·234, D = 0·585 as likely parameters, and (iii) a site with parameters near the values λ = 0·207, D = 0·322.Mössbauer and ESR evidence suggests that the principal sites of Fe3+ substitution are octahedral. The presence of Fe3+ in adjacent cation sites leads to a very broad resonance centred near geff = 2. Other resonances in the spectra are attributed to the effect of trapped holes, some at least of which are situated at oxygen sites adjacent to Al3+ ions substituting in sites normally occupied by Si4+.Hyperfine effects due to the presence of the transition ions Mn2+ and (VO)2+ are also observed.
On the calculation of one-dimensional X-ray scattering from interstratified material
Authors: Cradwick P. D. 
Published: December 2006

AbstractA method is given for calculation of X-ray scattering from interstratified materials which is applicable to components that do not possess centres of symmetry. This procedure allows contributions from interlamellar material to be included in the calculation without any assumptions being imposed by the method on the composition of the components. The method is in fact a simplification of the general formula given by Kakinoki & Komura (1965).
Surface properties of mixed Cu(II)—tetraalkylammonium montmorillonites
Authors: McBride M. B. , Mortland M. M. 
Published: December 2006

AbstractInitial exchange of Cu(II)-montmorillonite by tetrapropylammonium (TPA) or tetramethylammonium (TMA) ions results in segregation of different ions in randomly interstratified layers, with particular preference for TPA over Cu(II) during exchange. More complete exchange reverses this preference and both Cu(II)-TPA and Cu(II)-TMA clays become more homogeneous. The copper ions of the homogeneous Cu(II)-TPA clays are not fully hydrated while the TMA ions have less effect than TPA on the hydration of copper, probably a result of the smaller radius and higher hydration energy of TMA. Methods of X-ray diffraction, thermogravimetric analysis, BET surface area determinations, as well as infrared and electron spin resonance spectroscopy, are used in supplying evidence of cation distribution and hydration properties of these clays. Definite changes in the properties of hydrated copper when associated with tetraalkylammonium ions on the clay surface are indicated.
Synthesis of kaolinite by homogeneous precipitation at room temperature
Authors: La Iglesia A. , Martin-Vivaldi J. L. 
Published: December 2006

AbstractA method of precipitation in homogenous solution has been used for the synthesis of kaolin minerals at room temperature. The method consists essentially in producing conditions for which a sufficiently slow rate of precipitation is maintained. In the particular case described in this paper, the conditions for homogenous precipitation are obtained by addition of an anion exchange resin in the OH form to an acidic solution (pH ≈ 4) of sodium silicate and aluminium chloride or acetate.The mineral species synthesized in each particular case depend on the kind of anions present in the original solution (chloride or acetate) and also on the nature of the exchange resin used.
A method for measuring the mineralogical variation of spoils from British collieries
Authors: Collins R. J. 
Published: December 2006

AbstractA semi-quantitative mineralogical analysis of colliery spoil by XRD has been developed and used to compare spoils from eight collieries, in connection with work on the production of synthetic dense aggregates from spoil. Phase analysis of clay, which constitutes over half of all these spoils, is carried out by comparing X-ray peak areas of oriented specimens after heating and treatment with ethylene glycol. Total clay is obtained by difference, after determination of quartz and other minerals by an internal standard technique, allowing calculation of the proportion of each clay mineral. The results are tested against chemical analysis and a semiquantitative X-ray analysis of the chlorite present indicated that it is a highly ferruginous variety. Differences are detected in the mineralogy of all eight spoils but, except for the predominance of kaolinite in the spoils from Scotland, these differences are small.