bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Conductance of Sodium Bentonite in Water
Authors: van Olphen H. , Waxman M. H.
Published: August 2006

The concept of surface conductance and its role in the interpretation of the formation resistivity factor of reservoir rocks is reviewed.

The specific surface conductance of a clay is determined for four narrow particle-size fractions of sodium Wyoming bentonite in conductivity water. The values are derived from the specific conductance of gels of these clays on the basis of the picture of an idealized cubic network structure of the clay plates. The average surface conductance for internal and external surfaces of the bentonites is found to be 3.2 × 10−19 ohm−1, which is 0.55 × the value expected when all exchangeable ions are assigned their infinite dilution mobility. The data are independent of particle size.

In addition, conductivity data are presented for clay suspensions in a wide range of concentrations. In extremely dilute suspensions, the contribution of the clay to the conductivity when expressed per unit weight of clay (the so-called “weight conductance”) is smaller than expected from an independent movement of particle and counter ions. This is interpreted to be partly a result of both electrophoretic and relaxation retardation, indicating that the electrical double layer on sodium bentonite has a condensed character. Probably part of the counter ions are entirely immobilized by adsorption on the surface.

With increasing clay concentration, further compression of the double layer increases the retardation effects and a further decrease of the weight conductance is observed. A minimum is reached at a concentration of a few tenths of one percent clay at which, according to viscosity and light absorption data, particle interaction becomes apparent. At this point, immobilization of the particles and bridging between the electrodes gradually eliminate the retardation effects, and surface conductance takes over. The weight conductance increases gradually until a constant value is reached in a concentration range of 5 to 12 g of clay per 100 ml gel, from which the above value of the specific surface conductance was computed.
Heterogeneity in Montmorillonite
Authors: McAtee James L.
Published: August 2006

X-ray diffraction patterns and cation-exchange data are presented for centrifuged Wyoming bentonite to demonstrate the heterogeneous nature of montmorillonite. It has been shown that in the bentonite samples studied, the montmorillonite can be separated into at least two fractions. One phase consists of essentially a sodium montmorillonite while the other consists of essentially a calcium-magnesium montmorillonite. It is postulated that these differences occur because of differences in the isomorphous substitutions within the montmorillonite crystal lattice.
Experimental Studies on Micas: A Synthesis
Authors: Yoder Hatten S.
Published: August 2006

The principal end members of the micas believed to be common in sediments have been synthesized and some of their stability relations determined. The polymorphs of muscovite and paragonite, the principal dioctahedral end members, obtained were 1Md, 1M and 2M1, and those of phlogopite and annite, the principal trioctahedral end members, 1Md and 1M or 3T. The range of stability of each of the polymorphs could not be fixed accurately because of the slow rate of transformation; however, the transformations 1Md → 1M → 2M1 were effected for muscovite and paragonite and 1M → 1Md or 3T and 2M1 → 1M or 3T for phlogopite. The growth characteristics of these micas in the laboratory are believed to be analogous to the formation of micas in sediments.

Knowledge of the synthetic mica.s contributes greatly to an understanding of the natural materials called illite, hydromica, and high-silica sericite. The dioctahedral members of these materials and related minerals may be delineated accurately in the system muscovite—Al-celadonite—pyrophyllite and their iron analogues. The trioctahedral members of some of the same materials may be outlined in the system phlogopite— eastonite—tale and their iron analogues. The postulated substitution schemes in these systems are mainly MgSi ⇌ AlVIAlIV, KAl ⇌ Si, and H3O ⇌ K. In materials intermediate between these systems, such as most biotites and vormiculites, the substitution of 3Mg ⇌ 2AlVI is of major importance. The mixed-layer structures involving micas are elucidated.
Reactions of Feldspar and Mica with Water at Low Temperature and Pressure
Authors: Garrels R. M. , Howard Peter
Published: August 2006

Muscovite and K-feldspar (adularia) were dry-ground to — 200/inch particles, which were suspended in water. These suspensions were “titrated” with KCl, and the pH was recorded as a function of KCl concentration and temperature. The results indicate that muscovite and adularia react with water to produce a surface film in which H+ has displaced K+. The “titration” curves show some characteristics attributable to exchange reactions, others apparently related to equilibria among solids of fixed composition. Maximum release of K+ from adularia by reaction with water is much greater than that from mica. The interpretation is made that the first result of reaction of mica and adularia with water is a surface layer that grades from an outer portion that is structurally disrupted to an inner portion that retains the original silicate structure but with H+ substituted for K+. Addition of K+ as KCl to the suspending solution displaces H+ from the disrupted zone, but all H+ originally taken up by the solids was not returned to the solution by concentrations of KCl up to 1.0 M. Experiments were of a few hours duration; work by others has shown that the disrupted zone releases appreciable concentrations of silica and alumina to solution over longer time intervals.

These hydrolysis experiments indicate that at 25°C an H-feldspar or H-mica structure is favored over a K-feldspar or K-mica structure except in solutions in which the ratio of aK+ aH+ exceeds 109–10 or 107–8 respectively. These ratios decrease in the temperature range 25-65°C by a factor of about 100.7. These results, where considered in relation to the observed behavior of feldspar and mica under weathering conditions, indicate that the major energy change for the reactions, $2\,mica + 5{H_2}O = \,3\,kaolin + \,2{K^ + }\, + \,2O{H^ - }$$3K - feldspar + 2{H_2}O = \,K - mica + 6quartz + \,2O{H^ - }$ can be considered to result from H+-K+ exchange, and that the energy contribution from other changes is small.
Factors Affecting Clay Formation
Authors: Barshad Isaac
Published: August 2006

Barshad’s method of calculating clay formation from the chemical analyses of the whole soil, the clay fraction, the nonelay fraction, and the mechanical analysis was applied to a large number of soils to determine the effect of climate, topography, parent material, vegetation and time on amount of clay formation. The amount of clay formed from 100 g of the nonclay fraction of the parent material was used as the yardstick for comparing clay formation in the different soils.

It was found that for a true evaluation of the effect of these factors on clay formation, it is necessary to determine clay formation in every horizon of a profile and that all soil profiles should be sectioned into horizons which are as nearly alike in thickness as possible. Maximum clay formation in a soil profile occurs in the horizon which is about 2–10 in. below the surface rather than at the immediate surface; as a rule, the amount of clay forming decreases below this maximum horizon. An increase in moisture and temperature enhances clay formation. The temperature factor mainly affects clay formation in the Great Soil Groups in the following order: Podzols < Gray Brown Podzols < Brown Earths < Chernozems < Prairies < Red and Yellow Earths (Latosols) < Laterites. Poor drainage enhances clay formation. Grass-type vegetation is more effective in clay formation than tree-type. Clay formation is greater from the finer grained and the more basic rocks. The more easily rocks fragment, the more clay is formed. The increase in age of a soil is believed to be expressed in the same manner as an increase in the intensity of clay formation, namely, as an increase in clay formation with depth and as an increase in the thickness of a soil profile. It was concluded that clay formation is relatively slow: clay forms at a rate ranging from 0.00001 g to 0.002 g of clay per year per 100 g parent material or from 0.6 to 120 lb of clay per acre foot of parent material per year.
Forces Between Suspended Bentonite Particles Part II—Calcium Bentonite
Authors: van Olphen H.
Published: August 2006

In a previous paper (van Olphen, 1956) data were presented for the rheological and sedimentation behavior of sodium bentonite suspensions in water. From these data particle interaction energies were derived. Analogous data have been collected for calcium bentonite suspensions. It was observed that more clay is required to obtain a gel or a certain sediment volume with calcium bentonite than with sodium bentonite. This result can be quantitatively interpreted on the basis of a larger average particle thickness in the calcium bentonite suspensions. It is furthermore concluded that the interparticle forces are of the same order in both calcium and sodium bentonite suspensions.
The Formation of Chlorite-Like Structures from Montmorillonite
Authors: Slaughter M. , Milne I. H.
Published: August 2006

Chlorite-like complexes of montmorillonite with magnesium hydroxide or aluminum hydroxide have been prepared under a variety of physical and chemical conditions. Requirements for the preparation of these complexes have been simplified considerably by the use of rapid mixing techniques. A complex may be formed either by precipitating the hydroxide in a clay suspension or by preparing the precipitate separately and mixing it immediately with the clay suspension. It is suggested that the process involves the adsorption of a layer of the precipitate over the entire surface of the montmorillonite unit layer rather than the direct formation of a structure in the interlayer space. It is considered that there is no appreciable permanent association of unit 10 Å layers of montmorillonite in a well stirred suspension, even in the presence of strong salt solution, but that instead most clay surfaces are exposed continually. The chlorite-like structure develops only upon association of the unit layers through aging or dehydration.

The aluminum hydroxide complex with montmorillonite differs somewhat from the magnesium type, but it has the approximate chlorite basal spacing. The complex shows a second-order basal diffraction spacing of low intensity, and forms regular expanded structures with water or ethylene glycol. A gibbsite structure for the interlayer material is most compatible with the x-ray data.

The occurrence of this process in sediments and soils is considered to be very probable, although it is premature to consider precise environments until more experimental data are available.
Geochemical Method for Determining Paleosalinity
Authors: Frederickson A. F. , Reynolds R. C.
Published: August 2006

The boron content of sea water increases linearly with salinity within the range tested. The boron content of the illite minerals in the clay mineral size fraction of many types of sedimentary rocks has been shown to increase with the “geologically known” salinity prevailing during deposition of the rocks. It is believed that boron is abstracted by the illitic clay minerals from sea water in proportion to the salinity of the sea water. This boron content is not substantially changed by other geological processes normally operative in sedimentary rocks. It is concluded that the boron content of illite minerals in sedimentary rocks can be used to evaluate the salinity of the sea prevailing at the time the sediment was deposited.
Clay Mineral Alteration in Some Indiana Soils
Authors: Droste John B. , Bhattacharya N. , Sunderman Jack A.
Published: August 2006

X-ray analyses of samples from thirteen soil profiles that were formed on glacial till, loess, and Mississippian limestones of Indiana indicate that (1) in some soil profiles chlorite of the parent material is changed completely to montmorillonite with intermediate stages of random mixed layers of chlorite-vermiculite-montmorillonite; (2) some of the illite of the parent material produces montmorillonite through random mixed layering of illite-montmorillonite, but the illite is not entirely altered in any profile; and (3) kaolinite may be produced as a weathering product, or it may remain unchanged from the parent material.
Some Conditions Affecting the Adsorption of Quinoline by Clay Minerals in Aqueous Suspensions
Authors: Doehler R. W. , Young W. A.
Published: August 2006

The adsorption of quinoline by Na+- and Ca2+-montmorillonite, illite, and kaolinite in water suspensions was studied for varying physico-chemical conditions. The shapes of the adsorption isotherms depended upon these imposed environmental conditions, which were quinoline concentration, pH, salinity, time, and temperature.

In order to be in the range of concentrations of organic materials in natural waters, these studies covered the concentration range, from 0 to several hundred ppm. Of the variables studied, pH was critical. Throughout the pH range 8.5–6.0, adsorption increased as pH decreased. The change in adsorption as salinity increased depended on pH, clay mineral, and quinoline concentration. In our experiments, samples reached equilibrium within 2–3 hr, and moderate temperature changes made little difference in adsorption amounts.

Under the same conditions, Na+-montmorillonite adsorbed the most quinoline, kaolinite the least, and Ca2+-montmorillonite and illite intermediate amounts.

Two mechanisms seem to control this adsorption: ion exchange and molecular adsorption. This paper attempts to explain the effects of the physico-chemical environment on adsorption by these two mechanisms.
Interpretation of the Composition of Vermiculites and Hydrobiotites
Authors: Foster Margaret D.
Published: August 2006

Formulas calculated from modern analyses of vermiculites and hydrobiotites show that these minerals resemble phlogopites and magnesian biotites in tetrahedral and octahedral layer composition, but usually have a higher proportion of trivalent octahedral cations. None of the formulas studied resembles those of ferroan biotites in composition.

In a few formulas the negative layer unit charge and the neutralizing positive interlayer charge are as high as those found in phlogopite; about 1.00 in the half-cell formula, but in most vermiculite formulas the charge on the layer unit and the interlayer charge are considerably lower than in phlogopite. Such a decrease in the amount of these charges may be due to oxidation of Fe2+ to Fe3+, which would increase the positive octahedral charge, and, consequently, decrease the layer unit charge. Oxidation of Fe2+ to Fe3+ also explains the higher proportion of trivalent octahedral cations in vermiculites and hydrobiotites.

Few papers furnish both cation exchange data and analyses of the samples studied; consequently it is difficult to correlate interlayer charge and cation exchange capacity, but empirically the interlayer charge multiplied by 200 yields a value that approximates the cation exchange capacity, provided the Mg has been allotted correctly between octahedral and interlayer positions.

On the basis of composition and charge relations, vermiculites may be interpreted as formed from phlogopites or magnesian biotites by replacement of K by Mg.
Industrial Applications of Kaolin
Authors: Murray Haydn H.
Published: August 2006

Kaolins are used in a multiplicity of industries because of unique physical and chemical properties. Shape, particle size, color, softness, and non-abrasiveness are physical properties that are especially important. Chemical properties, such as comparatively low base exchange capacity, as well as other chemical properties of the kaolin surface, and relative insolubility, are governing in many uses. In 1960, well over 2,000,000 tons of kaolin was used in the United States, more than one-half of which was consumed by the paper industry. The relationships between physical and chemical properties are discussed in the application of kaolin to paper, rubber, ceramics, plastics, ink, catalysis, insecticides, and numerous other uses. A few new uses of kaolin are discussed along with a short gaze into a crystal ball to see what the future may hold for that useful mineral, kaolin.
Sepiolite and Related Compounds: Its Stability and Application
Authors: Preisinger Anton
Published: August 2006

The unit-cell characteristics and structures of sepiolite, ferri-sepiolites (xylotile, mountain wood, gunnbjarnite), loughlinite and palygorskite (attapulgite) and their structural relationships are discussed. The chemical, morphological and thermal properties are explained by their structures. The unit-cell characteristics and structures of sepiolite “anhydride”, loughlinite “anhydride” and palygorskite “anhydride” are given. Under low water vapor pressure the phase transformations sepiolite to sepiolite “anhydride” and palygorskite to palygorskite “anhydride” are reversible. It was not possible to synthesize sepiolite in the system MgO−SiO2−H2O under confined pressure within a range of 80° to 300°C

The possibility of the application of sepiolite and related compounds in industry, specially in the automobile industry, is referred to.
Studies in Position and Mobility of the H Atoms in Hydrous Micas
Authors: Rosenqvist I. Th.
Published: August 2006

The hydrogen content of dioctahedral and trioctahedral micas has been investigated by means of infrared spectroscopy and radioactivo measurements. Dioctahedral and trioctahedral micas have been treated with deuterium oxide and tritium-bearing water. The introduced isotopes of hydrogen have been determined after various thermal treatments.

It is concluded that dioctahedral hydrous micas may represent mixed crystals between K(Si3Al)Al2O10(OH)2 and H2O(Si3Al)Al2O9(OH)3, whereas trioctahedral micas seem to represent mixed layer minerals between phlogopite and vermiculite.
Cell Dimension Studies on Layer-Lattice Silicates: A Summary
Authors: Radoslovich E. W.
Published: August 2006

The statistical techniques of multiple regression analysis have been used to obtain more reliable formulae relating the cell dimensions especially the b-axis) of layer-lattice silicates to their composition or structural formulae. This allowed the significance of each coefficient to be expressed precisely and so provided rigorous tests for certain structural concepts about the different factors affecting cell dimensions. More recently an explicit theory has been developed about the various forces controlling the layer-lattice silicate structures which (a) removes some anomalies, (b) explains many variations in accurate bond lengths and angles, and (c) has several interesting structural implications for properties such as polymorphism, composition limits, crystal morphology, and stability under weathering. This paper summarizes work now being published in extenso elsewhere.
Argillic Alteration and Uranium Emplacement on the Colorado Plateau
Authors: Kerr Paul F. , Jacobs Marian B.
Published: August 2006

Argillic alteration is recognized in association with uranium deposits on the Colorado Plateau and along border areas. Alteration and mineralization are geometrically related in sedimentary strata where solution conduits result from lithologic and structural changes. The association also exists in collapse features and in breccia pipes. Occasional diatremes bearing uranium point to hypogene solution activity following igneous invasion as one original source for uranium ions. In several places ascending fluids apparently were confined under sufficient pressure to blast consolidated strata into vertical chimneys of brecciated masses. Pipes and fracture systems which transect porous strata provide paths along which hypogene solutions may ascend from depth and migrate horizontally. Alteration may extend both vertically and horizontally, encircling such areas.

Occasionally silica or carbonate precipitation accompanies uranium. Where found, well-marked masses of carbonate or silica replace sedimentary strata. Field conditions demonstrate upward migration of solutions. Often silica and carbonate may be dissolved from country rock and redeposited at higher levels. The silica minerals involved are quartz, chalcedony, and opal; the carbonates, calcite, dolomite and siderite.

The identification of mica polymorphs close to ore, corresponding to those created at elevated temperatures in the laboratory; the recognition of dickite in gouge zone veinlets associated with primary sulphides; uranorganic complexes; and replacement textures involving multiple pseudomorphs after a single mineral, further indicate alteration by hypogene solution.

Uranium deposition is favored by precipitating agents peculiar to certain strata. Hydrogen sulphide, produced by decaying fossil plant detritus, or petroliferous material, appears to have been an effective precipitating agent. Strata often involved are members of the Chinle or Morrison Formations. These units provide an environment with sustained reducing conditions favorable for uranium precipitation. The reduction of hexavalent uranium in solution occurs to the less soluble tetravalent form. Accompanying bleaching of red beds also suggests reducing conditions.
The Nature of Illite
Authors: Gaudette H. E. , Eades J. L. , Grim R. E.
Published: August 2006

Chemical composition, X-ray diffraction and other
analytical data of a series of samples of clays that are composed
essentially of illite are presented. The physical properties of these
samples are given and related to variations in the composition and character
of the illites.

Data indicate that these illites have less potassium than
well-crystallized micas and some of them are not essentially mixed-layer
structures, It is concluded, therefore, that illite is not necessarily a
mixed-layer material.
Expansion of Potassium-Depleted Muscovite
Authors: Scott A. D. , Reed M. G.
Published: August 2006

Muscovite samples were K-depleted with NaCl-NaTPB
solutions. By varying the extraction period, samples that varied in total K
from 219 to 15 meq per 100 g. were prepared. This treatment did not change
the layer charge in the mineral, but it did increase the basal spacing of
the mineral from 10 to 12.3 Å.

The changes in basal spacing that occurred when increasing amounts of
interlayer K were replaced by Na and the effects of subsequent treatments
for the removal of KTPB were determined with two size fractions. In each
case, the interlayer K at the periphery of the muscovite particles was
replaced by Na, and a fringe of K-depleted mineral with a basal spacing of
12.3 Å developed. In a <50µ sample the particles retained an inner core
of 10 Å mineral as the weathered fringe increased. There was no evidence of
interstratification. With this sample there was considerable Na trapping
when the KTPB was removed with NH4Cl-acetone-water
solutions. On the other hand, with a <2µ
sample, mixed-layer structures developed as K was removed, and less Na
trapping occurred. Na trapping was reduced by removing the KTPB with boiling
NH4Cl.

Undried Na-degraded muscovite with only 15 meq K per 100 g did not
expand beyond 12.3 Å. The NH4-degraded muscovite
samples had a basal spacing of 10.4 Å.
Discussions and Recommendations Concerning the Nomenclature of Clay Minerals and Related Phyllosilicates
Authors: Brindley G. W.
Published: August 2006

Attempts to find a generally acceptable scheme of classification and nomenclature for clay minerals by the nomenclature committees of The Clay Minerals Society (C.M.S.), the Comité International pour l’Étude des Argiles (C.I.P.E.A.), and the International Mineralogical Association (I.M.A.) are summarized. The C.M.S. committee has been working on this problem continuously since 1961 and has transmitted its views to C.I.P.E.A., first at the time of the Stockholm meeting, 1963, and subsequently, in more detail, after receiving the first draft of the C.I.P.E.A. proposals. The C.I.P.E.A. committee held discussions in Stockholm, 1963, and subsequently submitted a first draft to 32 nations; from the replies received, a final draft of the C.I.P.E.A. proposals was prepared and submitted to the I.M.A. in 1964. The report from the I.M.A. was made available in August, 1965.
Quantitative Clay Mineralogical Analysis of Soils and Sediments
Authors: Alexiades C. A. , Jackson M. L.
Published: August 2006

The objective of this paper is to present flow sheets for a system of quantitative minera-logical analysis of clays of soils and sediments and to show representative results. Selective dissolution analysis by the Na2S2O7-HCl-NaOH procedure yields the quartz and feldspar contents (0 to 63%) and differentiates feldspar K from mica K. The NaOH-thermal system of selective dissolution yields the allophane plus gibbsite, kaolinite plus halloysite, and dickite contents (0 to 84% for the sediments; 1 to 25% for soil clays) Mica contents (0 to 92% for the rock specimens, 7 to 43% for soil clays) are determined by nonfeldspathic K (and Na). Vermiculite contents (1 to 97% of specimens; 3 to 21% for soil clays) are measured by blocking of interlayer CEC by drying at 110°C while K saturated and replacing with NH4Cl. Montmorillonite (and palygorskite) contents (0 to 85% of specimens; 3 to 36% of soil clays) are determined by the CEC not blocked by the K and NH4 sequence for vermiculite. Chlorite contents (0 to 85% for specimens; 0 to 37% for soil clays) are determined by thermal gravimetric analysis, after allocation of OH water lost between 300 and 950°C to other hydrous minerals determined.

The best evidence of the accuracy of the system of analysis lies in the consistent total recovery of 24 standard mineral samples averaging 100.4 ± 1.3 (± standard error of means) and of 22 soil clay samples averaging 99.5 ± 0.8. The different constituents were present in widely different proportions in the various samples, and were determined by independent methods. The complementary total of near 100% (maximum range 95 to 105% for specimens; 95 to 103% for soil clays) for the analyses is a significant measure of the specificity of the several determinations.
Kinetics of Reactions in the Conversion of Na- or Ca-Saturated Clay to H-Al Clay
Authors: Basin Amos , Ravikovitch S.
Published: August 2006

H-ion was added to Na or Ca bentonite suspensions. The H-ion was added either in solution, as HCl, or adsorbed on a cation exchange resin. The variation with time of the quantities of H and Al in various phases of the system was determined.

In the first stage of the reaction both exchangeable H and exchangeable Al on the clay increased rapidly. Several facts showed that the exchangeable Al was not liberated by crystal structure decomposition. It is postulated that its appearance is the result of a rapid dehydroxylation, of hydroxy Al groups located at plate edges or adsorbed on basal planes, producing water and trivalent Al ions.

During the second stage of the reaction, spontaneous self-decomposition of the clay structure takes place. It was found that when the H-clay in alone in suspension or with low concentration of acid, the decomposition stops after the liberation of a limited quantity of Al. Most of this Al is adsorbed on the clay and it becomes the prevailing exchangeable ion. On the contrary, when the H-clay is aging in the presence of H-resin, a system of consecutive reactions is operating. In this system, Al liberated from the structure is transferred to the adsorbed state in the clay and from there to the resin. As a result the decomposition reaction does not stop as in the absence of the resin, but is carried further.
Kaolinite Crystallization at Room Temperature by Homogeneous Precipitation—III: Hydrolysis of Feldspars
Authors: La Iglesia A. , Martin-Vivaldi J. L. , Lopez Aguayo F.
Published: August 2006

The kaolinite crystallization by homogeneous precipitation with previous hydrolysis of the feldspars added has been followed by pH and potassium concentration measurements. The synthesized products were studied by X-ray powder diffraction and electron microscopy and consist of kaolinite and mica, accompanied occasionally by traces of smectite. The relative quantities of the synthesized minerals depend fundamentally on the supply rate of the alkaline ions.
High Extraction Magnetic Filtration of Kaolin Clay
Authors: Iannicelli J.
Published: August 2006

A new magnetic separation technique combines high magnetic fields, extreme gradients, and controlled retention time to separate feebly magnetic mineral contaminants from kaolin.

Extraction of pyrite, siderite, hematite, iron stained anatase, and mica by magnetic filtration of kaolin significantly upgrades brightness of many sub-marginal deposits and reduces consumption of reagents in processing.
Montmorillonite Pseudomorphs after Amphibole from Melbourne, Australia
Authors: Cole W. F. , Lancucki C. J.
Published: August 2006

Well developed smectite “crystals” up to 10 mm long, which probably are pseudomorphic after titaniferous hornblende phenocrysts, are present in a weathered dike in a Melbourne clay pit. The pseudomorphs contain 77 per cent of montmorillonite as determined by X-ray powder diffraction, differential thermal analysis, thermo-gravimetric and chemical analysis. The pseudo-hexagonal shape of the pseuodomorphs probably reflects the original crystal habit of the hornblende. The mechanism of alteration of an amphibole to a smectite is discussed.
Cation and Silica Relationships of Mica Weathering to Vermiculite in Calcareous Harps Soil
Authors: Henderson J. H. , Doner H. E. , Weaver R. M. , Syers J. K. , Jackson M. L.
Published: August 2006

A steady state reaction of apparent equilibrium of K mica + Ca2+ ⇄ Ca vermiculite + K+ was indicated by prolonged dissolution extractions from Blount soil clay (from northern Indiana) abundant in dioctahedral mica and vermiculite, with log Keq = 2.92 for the reaction when extrapolated to infinite time. From this and published free energies of formation of mica and kaolinite, a mineral phase stability diagram depicting the phase joins of Ca vermiculite, muscovite, and kaolinite was constructed with the solute activity functions pH-pK+, 2pH-pCa2+, and pSi(OH)4. These solute functions for 14-day reactions of calcareous (and dolomitic), poorly drained Harps soil (from central Iowa) fell near the calcite-dolomite-CO2-H2O phase join, suggesting equilibrium. These functions for Harps soil and the control minerals muscovite, biotite, and (or) vermiculite plus calcite were plotted on the mica-vermiculite stability diagram for various CO2 partial pressures. The points fell on the vermiculite-stable side of the mica-vermiculite plane at CO2 partial pressures of 0.15 and 0.20 atm (similar to soil air that would exist under frozen soil during winter and early spring; 2pH-pCa2+ ≃ 10.3). They fell on the muscovite-stable side of the muscovite-vermiculite plane at CO2 partial pressures of 0.0001 and 0.001 atm (similar to soil air under natural summer conditions; 2pH-pCa2+, 13.6 and 12.6, respectively) and therefore K+ (and 137Cs+ in rainfall) would be expected to be fixed.

The 2pH-pMg2+ values determined for Harps soil at the various CO2 partial pressures plotted either in the Mg montmorillonite stability field or on the Mg-montmorillonite-kaolinite phase join, in concordance with the abundance of montmorillonite and some kaolinite in the medium and fine clay fractions. The solute values for the nearby Clarion soil (upland, noncalcareous) plotted on the montmorillonite-kaolinite join, or with higher CO2 partial pressure, in the kaolinite stability area. The Gibbs free energy of formation (△Gf0) for a dioctahedral Ca vermiculite of −1303.7 kcal per 010 was determined from the Keq. The solute functions for the Blount soil showed kaolinite to be the thermodynamically stable phase with respect to dioctahedral mica and (or) vermiculite. The 14-day solute values for the Harps and upland Clarion soils were also on the kaolinite stability side of the kaolinite-vermiculite join. The kinetics of kaolinite formation in the upper midwestern U.S.A. are apparently slow on a scale of ~ 104 years.
Scan Electron Micrographs of Kaolins Collected from Diverse Environments of Origin—II
Authors: Keller W. D.
Published: August 2006

Scan electron micrographs (SEM) show the textures of ball clay, plastic refractory clay, flint clay, and of kaolins from Cornwall, U.K., and Brittany, France. The texture of ball clay is a swirl and ragged-flake pattern. Plastic refractory clay shows a transition in texture from ball clay to plastic, semi-plastic, to semi-flint, and flint-clay. Flint-clay texture exhibits a matrix of tiny, compactly interlocked clay grains in which may be interspersed small, tight books and sheaves of kaolinite. The plastic to flint clays are interpreted to be sequential components of the flint-clay facies. In one sense they represent elements in clay diagenesis.

Kaolins from the Cornwall district, U.K., and Brittany, France, show more similarity than dissimilarity in texture. Evidence from texture suggests that while hydrothermal action at Cornwall initiated alteration of the granite, the last significant process of kaolinization there was weathering.
Studies on Adsorption of Telone—II: Adsorption of Telone on Montmorillonites
Authors: Singhal J. P. , Kumar Dinesh
Published: August 2006

The interaction of telone with acid and base saturated montmorillonite furnished adsorption isotherms which possessed combined features of H (high affinity) and C (linear rising) class isotherms; a fall in pH, an increase in electrical conductivity and formation of chloride ions. The observations were indicative of a process of chemisorption, both at the planar and lateral sites of montmorillonites, followed by penetration and swelling of the substrate micropores with telone. A reaction mechanism for the process of chemisorption has been proposed.
The Structures of Ornithine-Vermiculite and 6-Aminohexanoic Acid-Vermiculite
Authors: Slade P. G. , Telleria M. I. , Radoslovich E. W.
Published: August 2006

Fourier syntheses have been used to establish the arrangement of organic molecules in the interlamellar regions of a 16.10 Å phase of ornithine-vermiculite and a 16.92 Å phase of 6-aminohexanoic acid-vermiculite. The organic cations form two layers parallel to the silicate surfaces in ornithine-vermiculite and in 6-aminohexanoic acid-vermiculite the organic cations form ascending and descending “stairs” from the silicate sheets.

Ornithine-vermiculite forms a true single layer polytype but by contrast 6-aminohexanoic acid-vermiculite is two-layered and has a true c axis of 34.09 Å. Since a two layered vermiculite was used as a starting material to prepare the organic complexes, exchangeable organic cations affect the stacking sequence of the silicate sheets.
The Birefringent Orientation and Relaxation of Clay Platelets as Affected by Particle Size, Saturating Cation and Clay Type
Authors: Schepers J. S. , Miller Raymond J. , Brown D. S. , Beavers A. H.
Published: August 2006

An electrooptic birefringence technique was employed to study the effect of particle size, saturating cation, and clay type on the rotational diffusion coefficient (a measure of the rate at which the particles rotate or relax within the solution) from a preferred orientation. These studies help elucidate the nature of the cation—water environment near the clay particles.

Previous work has shown that some clay particles orient at both low and high voltages due to a permanent dipole and an induced dipole, respectively, whereas other clays under similar short-duration pulses orient only at high voltages. The permanent dipole was attributed to the iron in the octahedral layer of the clay mineral, whereas the induced dipole was probably due to a redistribution of the diffuse double-layer cations. This study shows that smaller clay particles orient more readily at low voltages and have greater rotational diffusion coefficients at high voltages. The higher the rotational diffusion coefficient, the faster the particles move in their surrounding water-cation environment. The effect of the saturating cation on the rotational diffusion coefficients was Na > Li > K for the permanent dipole and K > Li > Na > Ca > Mg for the induced dipole orientation. Previous results (Schepers and Miller, 1974) are interpreted to mean that a particle in dilute suspension can rotate independently of its environment only when the salt concentration in the surrounding medium approaches zero. At higher salt concentrations, or if the particle environment is perturbed by an electric field, the particle rotates with a water shell. As the concentration of salt or strength of the electric field increases further, either the viscosity of the surrounding solution increases or the size of the rotating shell is greatly increased. Thus, the water around clay particles appears to be structurally different than normal, and this condition is probably caused by the nature of the clay—cation interaction.
Clay Mineral Studies of the Lower Permian Havensville Shale in Kansas and Oklahoma
Authors: Lee Moon J. , Chaudhuri S.
Published: August 2006

Analyses of samples of the Havensville Shale, collected from six localities in Kansas and northern Oklahoma, showed that the distribution of clay minerals and chemical variations in the clay minerals were related to changes in the sedimentary facies. The major clay minerals assemblages were: (1) illite, mixed-layer illite—montmorillonite, and regularly interstratified chlorite-vermiculite in the shaly facies of northern and central Kansas, (2) montmorillonite, illite and mixed-layer illite-montmorillonite in the calcareous shale and algal limestone facies of southern Kansas, and (3) kaolinite, illite and mixed-layer illite—montmorillonite in the sandy facies of northern Oklahoma. Differential settling and transportation of clay detritus were the major factors in the pattern of distribution of the clay minerals. Regional differences were noted in the abundance of 2m illite polymorphs, the K/Rb ratio and the illite 001/002 intensity ratio. Some structural variations and chemical differences among the clay minerals were consequences of modifications during deposition in different environments and diagenesis.
Scan Electron Micrographs of Kaolins Collected from Diverse Origins—III. Influence of Parent Material on Flint Clays and Flint-Like Clays
Authors: Keller W. D.
Published: August 2006

The nature of the parent material from which flint clay or flint-like clay is derived may modify the texture of the clay as observed by SEM. Flint clays occurring in Pennsylvanian-age swamp basins into which were transported residues weathered from sedimentary country rock exhibit a texture of interlocked kaolin pockets and sheaves. On the other hand, flint clay or flint-like clay derived by weathering of volcanic ash exhibits a texture resembling, on a micro-scale, the scalloped, “oak-leaf” pattern of montmorillonite. The interpretation is that an expanding clay having a transitional role between the ash and the kaolinite is the donor source of the micro-scalloped pattern inherited by kaolinite. X-ray powder diffractograms of the clays support the interpretation.
Reduction and Oxidation of Fe3+ in Dioctahedral Smectites — 1: Reduction with Hydrazine and Dithionite
Authors: Rozenson I. , Heller-Kallai L.
Published: August 2006

Hydrazine and dithionite, both of which are strong reducing agents, react differently with various dioctahedral smectites. Both the nature of the reducing agent and the structure of the clay affect the course of the reaction. Hydrazine reduces octahedral Fe3+ efficiently if the mineral has a low tetrahedral charge. The reducing action of dithionite does not depend upon the charge.

The results obtained by different physical methods of investigation suggest that reduction of iron is associated with protonation of an adjacent OH group. The Fe2+ formed is readily re-oxidised but the structural changes occurring on reduction are reversible only when Al-OH-Fe, but not when Fe-OH-Fe associations are involved. Reaction mechanisms are proposed and changes in the distribution of iron in the octahedral sites are discussed.
Reduction and Oxidation of Fe3+ in Dioctahedral Smectites — 2: Reduction with Sodium Sulphide Solutions
Authors: Rozenson I. , Heller-Kallai L.
Published: August 2006

Reaction with Na2S solutions at high pH led to almost complete, reversible reduction of iron in montmorillonite, whereas the structural iron of nontronite persisted in the ferric form. Concentrated Na2S solutions caused severe corrosion of nontronite and extracted appreciable amounts of iron, which was precipitated as sulphides. In contrast the morphology of montmorillonite was preserved and only very minor amounts of iron were extracted. These differences were attributed to the high concentration of Fe-OH-Fe groups in nontronite, which are unstable on reduction. The difference between Na2S and other reducing agents is discussed.
Interpretation of Infrared Spectra of Oxidized and Reduced Nontronite
Authors: Stucki J. W. , Roth C. B.
Published: August 2006

Infrared spectra of nontronite reveal shifts to lower wave, number in peaks located at 3570, 1030, and 821 cm-1, which are assigned to vibrational modes for O-H stretching, Si-Ob (basal oxygens) tetrahedral vibrations, and FeO-H deformation, respectively, as the Fe2+ content increases upon reduction. A pleochroic shoulder at 1110 cm-1 resulting from Si-Oa (apical oxygens) interactions appears to be unchanged with reduction. The absorption band at 848 cm-1 shifts to higher energy with reduction of structural iron, and persists at 840 cm-1 after complete deuteration of structural hydroxyls. The band is assigned to a Fe-OH mode where the OH moves as a unit. The shift in the Si-Ob mode to lower vibrational energy with reduction may indicate a decrease in stress forces between the tetrahedral and octahedral sheets.
The Surface Reactivity of Vermiculite Towards Hexamethylene Diisocyanate (HMDI)
Authors: Siffert B. , Biava H.
Published: August 2006

The reaction of hexamethylene diisocyanate with the surface of heat-activated vermiculite parallels the reactions with the oxides SiO2, Al2O3, MgO considered individually, which a number of authors have already described. The fixation ratio is about 5 molecules per 100 Å2 area. Nearly one half of the grafted molecules retain a “free” isocyanate function, which is requisite for a subsequent polyaddition of the processed mineral. The interaction with vermiculite occurs according to three principal processes; (i) formation of a surface urethane, (ii) formation of a surface carbamate, (iii) fixation by hydrogen bonds.
Interaction of Petroleum Heavy Ends with Montmorillonite
Authors: Clementz David M.
Published: August 2006

Adsorption of asphaltenes and resins onto montmorillonite occurs rapidly and to a large extent irreversibly under near-anhydrous laboratory conditions. Factors which influence the adsorption are the exchangeable cation on the clay, the basic nitrogen components of the molecules, and the solvent. As a result of this adsorption, the physical and chemical properties of the clay are drastically altered. The fundamental principles revealed in this study lead to a better understanding of the physical and chemical behavior of clays in petroleum reservoirs.
The “Layer Charge” of Regular Interstratified 2:1 Clay Minerals
Authors: Lagaly G.
Published: August 2006

Alkylammonium ion exchange on mixed-layer minerals gives detailed information about the variation of cation density in succeeding interlayer spaces. Three mixed layer samples from Japan (supplied by Dr. H. Kodama) were investigated. Their nearly 1:1 interstratification is based on regularly alternating high- and low-charged interlayer spaces, which are caused by a regular sequence of polar layers. The cation density in the high-charged interlayer spaces is >0.8 eq/(Si, Al)4O10. The low-charged interlayer spaces have an average cation density of 0.4 eq/(Si, Al)4O10 and heterogeneous charge distribution. The kind of heterogeneity of the Goto Mine sample differs from that of the Yonago Mine and the Honami Mine samples.

The Goto Mine specimen has a rather regular sequence of the low- and high-charged interlayers in proportions close to 0.50:0.50. The other two samples contain interlayer spaces with pronounced unsymmetrical charge distribution. The Yonago Mine sample probably has in random distribution with the polar layers about 10% mica-like layers segregated to packets of three and more layers; the ratio of high-charged interlayers to the low-charged ones is increased to about 0.55:0.45. The Honami Mine sample probably contains isolated mica-like layers or pairs of them. The proportion of the high-charged interlayers is estimated to be about 0.53:0.47 and is lower than determined by Kodama from the glycerolated sample.

The samples investigated may be considered as end-members of a series of interstratified specimens which begins with smectites with mixed-layer like charge distribution.
Behavior of Kaolinite Pellets at Elevated Temperatures
Authors: Flank W. H.
Published: August 2006

Dimensional changes in kaolinite pellets as a function of temperature show two sharp shrinkage “steps,” at about 450–550°C and 900–980°C, which are roughly comparable in magnitude. Isothermal heat-soaking tests confirm that the rates for both are kinetically controlled. Water vapor inhibits shrinkage at low temperature but promotes shrinkage at high temperature. Both the former reaction, related to dehydroxylation, and the latter reaction, related to “mullitization,” take place at temperatures well below those observed in DTA, TG, and other measurements, indicating that bond-breaking is a necessary prelude to transitions at higher temperatures.

Bonding energy changes, as measured by X-ray fluorescence shifts, were used in interpreting the phenomena involved. The relative absence of bonding energy changes in the aluminum until the range 950–1100°C, and the presence of such changes in the silicon, suggest that high-temperature energy release is probably related to segregation or crystallization of silica, rather than of an aluminum-containing phase. Caution must be used in interpreting bonding energy changes, and in distinguishing kinetic and thermodynamic contributions to dynamic phenomena.
The Interaction Between Roundup (Glyphosate) and Montmorillonite. Part I. Infrared Study of the Sorption of Glyphosate by Montmorillonite
Authors: Shoval S. , Yariv S.
Published: August 2006

The reaction between the herbicide “Roundup,” (PAH)3G, which is the commercial name of the iso-propylammonium salt of glyphosate (H3G, N-phosphonomethyl glycine), and montmorillonite was studied. The adsorption of the anionic component of Roundup glyphosate anion, G−3, from an ethanol solution is achieved by repeated immersion of the clay film in the alcohol solution followed by drying for 6–12 hr after each immersion. During the adsorption process the surface acidity of the interlayer space must be sufficiently high to protonate the anion. A zwitterion glyphosate is thereby formed in the interlayer space. Association forms are obtained in the interlayer space in which the COOH and the PO3H groups are linked to the exchangeable cations through water bridges. Adsorption of the glyphosate anion from aqueous solution of Roundup occurs when this anion forms a neutrally or positively charged complex with the exchangeable cation. This may occur with Al- and Fe-montmorillonite, when the molar ratio glyphosate:metal is such that a complex with a 1:1 ratio can be formed in the interlayer space. To clarify the reaction mechanism, adsorption of glycine by montmorillonite from ethanol solution was also studied. The associations obtained between glyphosate and exchangeable cations are less variable than those obtained between glycine and exchangeable cations in the interlayer space of montmorillonite. The following species of adsorbed glycine were identified: glycinium cation, zwitterion glycine, glycine complexed with metal cations either as a monodentate or as a bidentate ligand. In the latter case a chelate is formed.