bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beidellite and Associated Clays from the Delamar Mine and Florida Mountain Area, Idaho
Authors: Post J. L. , Cupp B. L. , Madsen F. T. 
Published: August 2006

AbstractThere has been much interest in the rare specimen of beidellite from the Black Jack Mine, Florida Mountain, Idaho. A variety of aluminous clays exists along veins such as the Black Jack vein, in rhyolite and latite flows, and in near-surface ash beds, often containing less than 1.0% MgO and 0.5% Na20. Associated clays include beidellite, illite, kaolinite, 10-Å halloysite, dickite, nacrite, rectorite and a tarasovite-like mineral. The predominant clay is mixed-layer illite—beidellite. The beidellites have Al2O3 contents ranging from about 28 to 33%, and predominantly Ca and K as interlayer cations. The typical beidellite dehydroxylation temperatures of about 595 °C readily differentiate the beidellite from montmorillonite, which has a dehydroxylation temperature in the range of 735 °C. A modified differential thermal analysis (DTA) method is given for readily estimating the interlayer cation populations of smectites, including Mg++ and Al+++ cations. Chemical analyses and layer charges of II beidellites from mines around the Black Jack Mine are given. The beidellites have an American Society for Testing and Materials (ASTM) classification of CR, φ value, internal friction angle of about 8° and an expansion pressure of about 9 kgf/cm2 (88.3 kPa), similar to that of nontronite.
Comparison of the Mineralogical and Chemical Composition of 2 Shales from the Western Canada Sedimentary Basin and the United States Gulf Coast
Authors: de Caritat Patrice , Bloch John , Hutcheon Ian , Longstaffe Fred J. , Abercrombie Hugh J. 
Published: August 2006

AbstractThe mineralogy and geochemistry of shales reflect the composition of the initially deposited precursor mud, subsequently modified by diagenetic processes. To see if significant geochemical differences exist between shales that mainly owe their present-day composition to either deposition or diagenesis, we compare the published mineralogical, bulk and clay-fraction geochemical, and clay-fraction O-isotopic compositions of 2 shales. One shale is from the Western Canada Sedimentary Basin (WCSB), and its composition mainly reflects primary (depositional) chemical and mineralogical variations (smectitic to illitic illite/smectite) within this unit. The other shale is from the United States Gulf Coast (USGC), and its composition mainly reflects mixed-layer illite/smectite (I/S) diagenesis of deposited smectitic clay material. The chemical and mineralogical trends of WCSB and USGC shales, including one of increasing illite content in I/S with depth or maturity, are essentially indistinguishable, in both bulk shale and clay fraction, despite the contrasting genetic interpretations for the origin of the contained I/S. Thus, similar mineralogical and chemical trends with depth or temperature can result either from inherited depositional compositional heterogeneity of the sediment, from burial metamorphism of shale or a combination of both. Interestingly, the O-isotopic compositions of the clay fractions from the WCSB and USGC are significantly different, a fact that reflects original clay formation from source material and water of quite different isotopic compositions. The discrimination between depositional and diagenetic contributions to shale composition continues to pose challenges, but a combination of bentonite, illite polytype, clay isotopic and trace and rare earth elemental analyses together with illite age analysis holds promise for future work.
Illite-Smectite Alteration and Accompanying Reactions in a Pennsylvanian Underclay Studied by TEM
Authors: Elsass F. , Środoń J. , Robert M. 
Published: August 2006

AbstractPennsylvanian underclay from Illinois is characterized by well-developed mineral zonation: towards the coal bed, marly limestone gradually evolves into carbonate-free clay, chlorite becomes undetectable and illite/smectite changes from ordered and illite-dominated into random and smectite-dominated, with both types present in the middle of the profile. Transmission electron microscopy (TEM) observations of the bulk material imply that disappearance of calcite is due to dissolution. Movement of SiO2in the upper part of the profile is evidenced by quartz cementation of clay aggregates; crystallization of kaolinite, by the presence of vermicular aggregates absent from less-altered samples. Illitic material in unaltered (limestone) samples consists of rare, large, Al-rich crystals of mica, interpreted as detrital, and abundant thin crystals of illite/smectite intimately mixed in approximately equal proportions with even thinner crystals of discrete illite. Both are more Mg- and Fe-rich than the large mica crystals and are interpreted as diagenetic, based on their1Mdpolytype and the correlation with coal rank. Illitic material of the upper, carbonate-free section of the profile contains the same 3 types of crystals, but in different proportions: illite/smectite crystals dominate and their composition is more smectitic. Two distinct morphologies of the aggregates of crystals with different proportions of the component layers are observed. It explains why 2 different illite/smectites are detectable by X-ray diffraction (XRD) in these samples. The analysis of chemical data suggests that the underclay is a residue after dissolution of all of the calcite and half of the quartz from the original limestone (paleosol and/or telogenetic process). The TEM observations are not decisive regarding the origin of variation within the illitic material. It may result from burial diagenetic illitization of more-smectitic material, similar to the composition preserved in the center of underclay profile, or it may represent telogenetic alteration of illitic clay by acid waters penetrating down from the coal bed. The aggradation model explains the increase in percent K2O, MgO and illite layers in the uppermost part of the profile. Whichever is the direction of reaction, it proceeds on an aggregate-by-aggregate basis and not fundamental particle-by-particle, and cannot be explained by simple opening or collapse of interlayers.
Characterization of Iron-Manganese Concretions in Kentucky Alfisols with Perched Water Tables
Authors: Zhang Min , Karathanasis A. D. 
Published: August 2006

AbstractIron-manganese concretions are common in upper sola of Alfisols in the Inner Bluegrass Region of Kentucky. Their nature and quantities appear to be related to the fluctuation of seasonal perched water tables above clayey argillic horizons. This study was conducted to examine changes in the macro-and micromorphology, chemistry and mineralogy of concretions as a function of size, color and soil depth. Total Mn and Fe contents increased, while SiO2 decreased with concretion size. Black concretions contained higher Mn, while brown concretions were higher in Fe. Crystalline Mn- and Fe-oxides fractionated with a sequential extraction procedure increased, but amorphous Mn and Fe decreased with concretion size. Goethite was the only crystalline Fe oxide mineral identified by X-ray diffraction (XRD) analysis. Manganese oxide minerals were very difficult to detect due to the diffuse nature of their XRD peaks and poor crystallinity. Examination of soil thin sections showed concretions of soil horizons overlying restrictive clayey layers to exhibit differentiated fabrics, sharp external boundaries and generally spherical shapes. Concretions found within clayey restrictive layers or above lithic interfaces usually had less structural organization, softer matrices and diffuse external boundaries due to longer term saturated conditions. Scanning electron microscopy (SEM) examinations suggested that the concretionary matrix, in spite of its density, has numerous cavities and an extensive micropore system within which dissolved plasmic Fe and Mn can diffuse and precipitate.
Surface Structural Model for Ferrihydrite
Authors: Manceau A. , Gates W. P. 
Published: August 2006

AbstractA structural model for the geometry of Fe(III) octahedra near the surface of finely divided ferrihydrite was elaborated based on the bond-valence theory and by considering the interaction of water molecules in the 2 nearest hydration spheres. In contrast to bulk Fe atoms, which are bonded to bridging oxo (O) and hydroxo (OH) ligands, surface Fe atoms are also octahedrally coordinated to H2O ligands forming the 1st hydration shell ((H2O)I). In the wet state, external water molecules of the 2nd hydration shell ((H2O)II) are singly H-bonded to (H2O)I, while they are doubly coordinated in the dry state. Accordingly, wet ferrihydrite contains twice as many sorbed water molecules as dry ferrihydrite, and the structural difference due to the 2nd hydration shell accounts quantatively for the 15% increase of ferrihydrite weight experimentally measured in moist atmosphere. The interaction of surface Fe atoms with their 2 nearest hydration spheres modifies the geometry of surface Fe octahedra as compared to bulk octahedra, and idealized Fe-OH and Fe-H2O bond lengths in the wet and dry state were evaluated by the bond-valence theory. Our structural model provides a sound crystal-chemical basis to describe many apparent incongruities of Fe X-ray absorption near edge structure (K-XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopic data that have led to differing interpretations of the coordination environment of Fe in ferrihydrite by various investigators.
Influence of Water on the Retention of Organic Probes on Clays Studied by IGC
Authors: Balard Henri , Saada Alain , Siffert Bernard , Papirer Eugène 
Published: August 2006

AbstractOil recovery is strongly related to the wettability of reservoir rocks that are formed of quartz grains attached by mineral hydroxides and clay minerals. Illites and kaolinites are the most active due to their high specific surface areas and electrical charge densities. Therefore, these minerals’ relative affinities for oil or water when in contact with a water-oil mix are of great importance. In order to model such a complex system, we used a mix of organic model molecules of the oil constituents and water vapor. Their interactions were estimated by inverse gas chromatography (IGC). IGC experiments were performed using a carrier gas with controlled humidity. By means of IGC at infinite dilution conditions, the dispersive component of the surface energy, γsd, was determined. A strong decrease of γsd, due to water molecules shielding the highest-energy sites, was observed. The energetic surface heterogeneity of the clays was examined using IGC at finite concentration conditions, allowing the determination of organic probe adsorption isotherms in the presence of water. From these isotherms, adsorption energy distribution functions were computed for propanol-2 and pyridine probes. Water mainly modifies the illite distribution functions, whereas practically no change was observed in the case of kaolinite. This observation is related to the higher hydrophilicity of illite as compared with kaolinite, and explains the different behaviors of the 2 clay families in oil reservoirs.
Intercalation of Halloysite: A Raman Spectroscopic Study
Authors: Frost Ray L. , Kristof Janos 
Published: August 2006

AbstractIntercalates from an ordered halloysite with urea and potassium acetate were studied using Raman microscopy. The urea intercalate showed new Raman bands at 3387, 3410, 3497 and 3598 cm−1 which were attributed to the formation of a urea-Si2O5 complex. New Raman bands were observed at 3585 and 3602 cm−1 for the potassium acetate intercalate with concomitant loss of intensity of the bands at 3635, 3655, 3675 and 3696 cm−1. These new bands were attributed to the hydrogen bonds formed between the acetate and the inner surface hydroxyl groups. Remarkable changes in intensity in the lattice region of the halloysite were observed, the foremost being the reduction of the intensity of the bands at 243, 271 and 336 cm−1. Pronounced changes in the bands at 913 and 143 cm−1 attributed to the Al-OH librations were also observed.It is proposed that 2 distinct types of intercalation were present, as exemplified by: 1) urea intercalate, where the intercalating molecule hydrogen bonds to the Si-O of the halloysite layers and 2) potassium acetate intercalate, where the molecule is hydrogen-bonded to the inner surface hydroxyls of the halloysite layer and interacts with the tetrahedral sheet of the next adjacent halloysite layer. The Raman spectra of the intercalated halloysite strongly resembled that of an intercalated kaolinite.
Conversion of Ferruginous Allophanes to Ferruginous Beidellites at 95 °C Under Alkaline Conditions With Alternating Oxidation and Reduction
Authors: Farmer V. C. 
Published: August 2006

AbstractFerruginous beidellites with Al:Fe atomic ratios up to 2.36 were obtained when solutions containing Al, Fe2+ and H4SiO4 were adjusted to pH 8.5 with Ca(OH)2 and incubated at 95 °C in the presence of CaCO3 as a pH buffer. Incubation took place under cyclic reducing and oxidizing conditions achieved by adding 2 mM hydrazine at 14–15-d intervals over a period of 10–13 weeks. During the 14–15-d cycle, atmospheric oxygen slowly diffused through the high-density polyethylene bottles used, causing a slow oxidation of Fe(II) to Fe(III). The infrared (IR) spectra of the products approached that of natural beidellite, but indicated little change in octahedral Al:Fe ratio in the products for starting Al:Fe ratios from 2.5 up to 3.5, which was the highest Al:Fe ratio at which a well-crystallized product was obtained. Chemical analysis showed the presence of more Al+Fe in the products than could be incorporated into a dioctahedral formula. After the excess was assigned to a hydroxy-aluminium interlayer, the formula of the most Al-rich beidellite was calculated to be 0.575Ca(Si6.85A1.15)(Al2.47Fe1.53)O20(OH)4. This composition lay within the range recorded for the ferruginous beidellites that form in Vertisols.
Frio Shale Mineralogy and the Stoichiometry of the Smectite-to-Illite Reaction: The Most Important Reaction in Clastic Sedimentary Diagenesis
Authors: Lynch F. Leo 
Published: August 2006

AbstractBurial diagenesis of shales of the Frio Formation resulted in an increase in the abundance of mixed-layer illite-smectite (I-S), albite and chlorite, and a decrease in the abundance of K-feldspar, illite and kaolinite. Some of the mineralogic trends determined in this study contrast with the results of Hower et al. (1976) and other studies of Frio shales. The differences are due to improvements in laboratory and clay quantification techniques since the time of the earlier research. I-S composition changed from ~20% to ≥80% illite, and mineralogic and chemical reaction of I-S continued throughout burial. Shale diagenesis was an open-system process that required addition of K2O and A12O3, and resulted in loss of SiO2. The amount of SiO2 made available by shale diagenesis is sufficient to be the source of the quartz-overgrowth cements in the associated Frio sandstones. The relationships between I-S diagenesis and fluid flow from shales into sandstones, generation of abnormal formation-water fluid pressure, onset of sandstone diagenesis and distribution of authigenic phases in sandstones indicate that reaction of the I-S in shales is one of the most important components of the sandstone/shale/formation water diagenetic system.
The Genesis of a Mordenite Deposit by Hydrothermal Alteration of Pyroclastics on Polyegos Island, Greece
Authors: Kitsopoulos Konstantinos P. 
Published: August 2006

AbstractThe vitric component of the silicic pyroclastic flows and surge deposits (Prassa ignimbrite unit), from the northwestern exposures of the pyroclastics formation of Polyegos Island, South Aegean Sea Volcanic Arc in Greece, is replaced by authigenic zeolite and clay minerals. Mordenite dominates, and clinoptilolite (heulandite type 3), illite and illite-smectite (I-S) are subordinate. Opal-CT, quartz, feldspar, biotite and halite complete the mineralogical suite. In the southwestern part of the pyroclastics formation (Myrsini pyroclastics unit), kaolinite, halloysite, alunite and amorphous silica are the major mineralogical constituents as a result of a strong hydrothermal alteration by solutions enriched in SO42-. Scanning electron microscope (SEM) examination proved that the 1st type of zeolites formed within the area were heulandite minerals, following the formation of smectite, as a result of the activity of pore fluids within the volcaniclastic pile. There was no substantial evidence to support a hypothesis that mordenite was formed with the heulandite minerals after the initial stages of glass dissolution, other than some very minor mordenite that was formed from a gel-like type of material. The majority of mordenite present is most often draped over and formed from the crystals of heulandite minerals. Heulandite minerals often show advanced dissolution effects. The mineral dissolution was due to the emplacement of rhyolite lava domes and flows and the associated temperature rise and circulation of hydrothermal fluids, which had also mixed with seawater. The volcanic activity raised the temperature and changed the pore fluid chemistry, and the more unstable members of the heulandite minerals group were transformed to mordenite. Clinoptilolite (heulandite type 3), which was found within a few samples, was thermally more stable than any heulandite type 1 or 2 phases initially present. Therefore, clinoptilolite was either transformed more slowly or within a very few cases, it has not been affected at all. A heulandite-minerals-derived material acted as the major precursor for the formation of mordenite. The temperature increase within the area and the later hydrothermal alteration effect are also indicated by the illitization of the smectite. Mordenite is also found to have formed from I-S clays. Overall, mordenite formed as a result of elevated temperature and high Na+ concentration.
Infrared Reflectance Study of Thermally Treated Li- and Cs-Montmorillonites
Authors: Karakassides M. A. , Petridis D. , Gournis D. 
Published: August 2006

AbstractThe structure of Li- and Cs-montmorillonites was studied using infrared (IR) reflectance spectroscopy. The spectra of heat-treated clays between 80 and 220 °C were analyzed by Kramers-Krönig inversion in order to obtain the optical and dielectric properties of the clays. The analysis revealed the transverse-optic (TO) and longitudinal-optic (LO) components of the asymmetric stretching vibration of Si-O-Si bridges. Major differences, in particular the systematic development of new bands, were found in the Li-montmorillonite LO and TO spectra with increasing temperature. These changes were attributed to the migration of the Li-cations into the layer structure.
Application of Inverse Gas Chromatography to the Study of the Surface Properties of Slates
Authors: Rodriguez M. A. , Rubio J. , Rubio F. , Liso M. J. , Oteo J. L. 
Published: August 2006

AbstractInverse gas chromatography (IGC) at zero surface coverage was used for determining the surface characteristics of a slate sample. Previously this sample had been characterized by means of X-ray diffraction (XRD), chemical analysis, infrared (IR) spectroscopy and nitrogen adsorption. Quartz, muscovite and chlorite were the minerals foming the slate. A well-defined mesoporous structure with pores of 15 Å of interlayer distance was observed. Chemical analysis and IR spectroscopy corroborated the X-ray results. The surface characteristics of the slate were defined in relation to nonspecific and specific interactions with organic molecules. In accordance with the nonspecific interactions, the London component (γSD) of the surface free energy gave an estimation of the surface energy of the slate sample. The obtained values for γSD were 140.0, 124.8, 108.2 and 96.8 mN m-1 at 100, 110, 120 and 130 °C, respectively. These values were characteristic of an inorganic sample of high surface energy. The values of the thermodynamic variables—differential heat of adsorption, free energy and entropy of adsorption—were in accordance with these results. At the same time, specific interactions were characterized by the ηπ parameter and the acid-base (KA, KB) indices. The positive value of ηπ (0.09 kJ mol-1) indicated the presence of Lewis acidic sites on the slate surface. The value of KA (acid index) of 1.17 was higher than the value of KB (base index) of 0.37; this result confirmed the acidic nature of the studied slate's surface.
Relationship Between Cation Exchange Selectivity and Crystalline Swelling in Expanding 2:1 Phyllosilicates
Authors: Laird David A. , Shang Chao 
Published: August 2006

AbstractA theoretical model describing the interaction between crystalline swelling and cation exchange selectivity is proposed for expanding 2:1 phyllosilicates. The model is based on the assumption that changes in basal spacing of a clay are phase changes, and that each phase of a clay has a different selectivity constant for a particular cation exchange reaction. Energy barriers stabilize the various phases over a limited range of interlayer ionic composition. These energy barriers cause hysteresis in crystalline swelling, which in turn causes hysteresis in cation exchange. Results are presented for an experiment involving Ba-Mg exchange on a synthetic fiuoro-hectorite. The results demonstrate key aspects of the proposed model, including a correlation between measured selectivity coefficients and basal spacings (R2 = 0.85), an abrupt change in basal spacing that corresponds with an abrupt change in selectivity and corresponding hysteresis in crystalline swelling and cation exchange selectivity. The results also demonstrate increased selectivity for the preferred cation (Ba) at high solution mole fraction of the preferred cation. This trend is opposite of that observed for heterogeneous natural smectites but consistent with predictions of the model for a homogeneous smectite.
Characterization of the Solids Obtained by Pillaring of Griffithite (High Iron Content Saponite) with Al-Oligomers
Authors: Vicente Miguel Angel , Suarez Mercedes , Bañares-Muñoz Miguel Angel , Martin-Pozas Jose 
Published: August 2006

AbstractGriffithite, a high Fe content saponite (Griffith Park, California) was pillared with Al polymeric solutions, using different Al/clay ratios. The cation exchange began when Al-polycation solutions were added, being completed during the dialysis of the samples. Pillared solids were obtained by calcination of intercalated precursors at 500 °C. The content of A12O3 increased from 7.35% in the natural griffithite to about 14% in the pillared samples, equivalent to the fixation of about 1.4 mmol Al per g of clay. The surface areas of the pillared griffithite were between 230–300 m2 g-1. The intercalation and pillaring of griffithite were easier than that of a less-crystalline nonferrous saponite.