bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-Angle X-Ray Diffraction Studies of the Swelling of Montmorillonite and Vermiculite
Authors: Norrish K. , Rausell-Colom J. A.
Published: August 2006

Various workers have studied the mechanism of swelling of Na-montmorillonite and have demonstrated that its ability to swell is due to water penetrating between the individual silicate sheets. In the present study intraerystalline swelling was followed by diffraction techniques which enabled the movement of the silicate sheets with respect to one another to be measured as a function of electrolyte concentration, with or without an externally applied load. The observations have been made on oriented flakes of Na-montmorillonite and single crystals of Li-vermiculite.

Qualitatively the minerals behave similarly when swollen in salt solutions. They both show an initial stage of crystalline swelling, after which there is an explosive increase to the gel state, and then the distance apart of the silicate sheets increases linearly with C-½, where C is electrolyte concentration. Quantitatively, however, their swelling is very different, particularly after the “explosion”, where vermiculite generally gives higher spacings than montmorillonite. There are two other important differences in the swelling of montmorillonite and vermiculite. Firstly, while the swelling of vermiculite appears to be reversible both with respect to electrolyte concentration and applied pressure, the swelling of montmorillonite shows a marked hysteresis. Secondly, in montmorillonite, swelling depends very strongly on pH or chemical treatment.

There is little doubt that the development of diffuse “double layers” gives rise to repulsive forces, which cause the silicate sheets to move apart. Van der Waals’ forces have been regarded as providing attraction, but it is found that, at the observed interlayer separations, the magnitude of these attractive forces is inadequate to balance repulsion, both in montmorillonite and vermiculite.

The present results demonstrate that in vermiculite swelling proceeds until the interlayer separation causes the repulsion between sheets to drop to a value of ~ 2.5 × 104 dyn/cm2. This attractive force, which limits swelling, appears to be independent of sheet separation and electrolyte concentration. In montmorillonite swelling is opposed by edge-to-face bonds between sheets, whose number and strength can be controlled by chemical treatment. These bonds act to resist any displacement of the sheets, either swelling or contraction. This mechanism is compatible with the observed swelling behavior of montmorillonite, and explains the differences between the swelling of this mineral and that of vermiculite where, because the sheets are considerably larger, the force arising from edge-to-face bonds is small or absent.
Characterization of Montmorillonite Saturated with Short-Chain Amine Cations: 1. Interpretation of Basal Spacing Measurements
Authors: Diamond Sidney , Kinter Earl B.
Published: August 2006

Basal spacing measurements were made for a montmorillonite saturated with a series of small aliphatic primary, secondary, and tertiary amine and quaternary ammonium cations, using wet, oven-dry, and glycerol-treated specimens. The spacings ranged from about 12 to 14Å, depending on the cation, indicating that in each case a monolayer of cations is interleaved between adjacent montmorillonite layers. The observed spacings are consistent with the concept that the cations are oriented with their minimum thickness in the c-axis direction, but it is possible that the smallest cations have a long axis in this direction and are partially embedded in the clay surfaces.

Montmorillonite saturated with cations containing up to four carbon atoms retained some sensitivity to water, as indicated by a slight contraction of the lattice on oven drying and rapid re-expansion on exposure to the humidity of the laboratory atmosphere.

For cations having a layer thickness less than glycerol, limited lattice expansion occurred on glycerol treatment, usually to a spacing sufficient to accommodate a single layer of glycerol molecules. Apparently the cations function as pillars separating the montmorillonite layers, and the glycerol molecules may expand the lattice as necessary to enter the spaces between the pillars. However, exceptions occurred with methylamine-saturated montmorillonite, in which both one- and two-layer complexes of glycerol were present simultaneously in the same specimen, and with trimethylamine-saturated clay, in which two different one-layer complexes were present. It is suggested that the glycerol in one-layer montmorillonite complexes may exist in two orientations, one leading to a layer thickness of about 4.1 Å, the other to a thickness of about 4.6 Å.
Mica-Type Layer Silicates with Alkylammonium Ions
Authors: Weiss Armin
Published: August 2006

More than 8000 different derivatives of mica-type layer silicates (muscovite, biotite, illite, vermiculite, beidellite, montmorillonite) with alkylammonium ions and different organic molecules as swelling liquids were prepared and characterized analytically by X-ray and chemical methods. The following results have been discussed in some detail.

Layer-lattice compounds are formed in simple stoichiometric relations. In n-alkyl-ammonium compounds, for instance, the sum (n-Cx,H2x+1NH3++n-CxH2x+1Y) per (Si, Al)4O10 is equal to 2.0 (Y = OH-, Cl-, Br-, NH2-, COH-, CONH2-, CN-).

The layer distance of the pure n-alkylammonium derivatives enables one to determine the charge density in the silicate layers. But in soils the ability of humic acids to undergo two-dimensional intracrystalline swelling and to react with alkylammonium ions must also be considered.

The properties of n-alkylammonium layer silicates are similar to those of alkyl-ammonium-uranium micas and of swelling vanadates (e.g. hewettite and pascoite). The swelling properties of alkyl-(α, ω)-diammonium ions are markedly influenced by the opportunities for hydrogen bonding. Mica-type layer silicates may show catalytic properties like protease or oxidase with ammonium ions, which are of general interest.
Adsorption by Organo-Clay Complexes—Part 2
Authors: Cowan C. T.
Published: August 2006

A detailed investigation of the adsorption of phenol and m-cresol from dilute aqueous solution by dodecyl- and tetradecylammonium bentonites has been carried out. The Freundlich isotherms for the tetradecylammonium bentonite system indicate that during adsorption, the process proceeds in two stages, the partial molar heat of adsorption changing from a positive to a negative value with a relatively small change in concentration of adsorbate. In the light of these findings, the aspects of the adsorption are discussed in terms of thermodynamic quantities, spatial considerations, and interlamellar expansion of the clay mineral.
X-Ray Diffraction Studies of Organic Cation-Stabilized Bentoniteby
Authors: Rosauer E. A. , Handy R. L. , Demirel Turgut
Published: August 2006

Studies of quaternary ammonium chlorides containing long unsaturated hydrocarbon chains have shown their effectiveness in stabilizing soils primarily by waterproofing the clay fraction. The nature of the interaction between organic salts and Wyoming bentonite was studied by means of X-ray diffraction.

Treatment of bentonite with a dialkyl dimethyl ammonium salt in an amount less than the exchange capacity results in the appearance of water-stable spacings of 10, 13 and 19 Å, but only if the sample has been dry cured. Moist curing a bentonite paste results in a marked expansion of the lattice despite treatment. The necessity of dry curing may relate to orientation of organic cations around bentonite aggregates; grinding prior to rewetting destroys the waterproofing action, and the clay lattice again expands.

Additions of the quaternary ammonium cations close to or in excess of the exchange capacity of the bentonite waterproofs regardless of dry curing or grinding, or both. Clays treated in this manner show spacings of the pure crystalline chemicals and other spacings which relate to interlayer penetration by water. There is no direct evidence for interlayer penetration by the organic cation, perhaps because of the unwieldy tetra-hedral arrangement of the organic molecule. The degree to which organic cations are held depends on the nature of the surface as the cations are readily leached from quartz powder but are held more strongly on kaolinite and bentonite.
Perspectives in Applied Organo-Clay Chemistry
Authors: Nahin Paul G.
Published: August 2006

Some aspects of organo-clay chemistry that have interested a growing number of scientists are reviewed and discussed. Particular attention is directed to published evidence for the “reality” of clay compounds, the possible effects of high energy radiation on clay properties, industrial applications of modified clays and the increasing number of patents being granted in this field of applied chemistry. A number of areas of inadequate information where further basic research could lead to useful applications is pointed out.
Attapulgite: Properties and Uses
Authors: Haden W. L.
Published: August 2006

The clay mineral attapulgite derives its non-swelling needle-like morphology from its three-dimensional crystal structure. The shape and size of the needles result in unique colloidal properties, especially resistance to high concentrations of electrolytes, and give high surface area, high porosity particles when thermally activated. Examples of industrial applications of attapulgite are reviewed with emphasis on how these characteristic properties function in the various end-uses.
Organophilic Clay-Base Thickeners
Authors: Jordan J. W.
Published: August 2006

The clay minerals, generally characterized by their small particle size, affinity for water, and response to chemical changes in their environment, are noted for their gelling and viscosity-increasing abilities in aqueous systems. Rendered organophilic by association with long-ohain organic compounds, several of the clay minerals exhibit similar or even greater gelling abilities in various organic liquids.

Methods of preparing organophilic clays are discussed and data shown for ion exchange reactions between long-chain organic cations and montmorillonite minerals. Properties of modified clays in various liquid systems are illustrated, and industrial applications are cited.
Density Studies in Clay—Liquid Systems, Part II: Application to Core Analysis
Authors: Deeds C. T. , van Olphen H.
Published: August 2006

In Part I (Deeds and van Olphen, 1961) pycnometric data on expanding clays in water and in other displacement fluids were analyzed in terms of inaccessible void space within aggregates and of possible density anomalies of the adsorbed fraction of the displacement fluids.

Further details of this work are reported, and the consequences for the interpretation of core analysis data are discussed. It is concluded that in core analysis the density of the connate water can be assumed to be normal while the fraction of the total pore space which is filled with oil is computed, provided that the total pore space is determined by using water or a polar organic liquid. If a hydrocarbon liquid or an inert gas is used, a small correction for inaccessible pore space can be applied.
Diagenesis of Clays in Sedimentary and Petroliferous Series
Authors: Kulbicki Georges , Millot Georges
Published: August 2006

In the argillaceous fraction of a sedimentary series of petroliferous sandstones from the Sahara two successive diagenetic changes are considered. The first is kaolinization of the original silicates. This is followed by illitization of the kaolinite by saline waters. The same formation is kaolinitic where it produces petroleum and illitic where it is nonproductive.
Effect of Radiation Damage on Mullite Formation in Kaolinite
Authors: Head C. M. , Moody W. E. , Mitchell Lane , Young R. A.
Published: August 2006

Kaolin was irradiated with 0.67 meV gamma-rays from a Cs137 source. Irradiation dosages of more than 1019 eV/g retarded mullite formation whereas smaller dosages appeared to have enhanced mullite formation slightly. It appears that preferentially oriented mullite formation from kaolinite is energetically favored and is adversely affected by radiation-produced nb/3 shifting of the Al ions. A possible mechanism for the effects of the radiation on mullite formation is suggested.
Proposed Reference Illite from the Ouachita Mountains of Southeastern Oklahoma
Authors: Mankin C. J. , Dodd C. G.
Published: August 2006

An exceptionally pure illitic clay is present in outcrops of the Blaylock Formation (Silurian) in the Ouachita Mountains of southeastern Oklahoma. Unweathered claystone samples from this unit in Beavers Bend State Park have been found to consist of a well-crystallized illite or hydrous mica. Impurities commonly found in illites such as non-clay minerals and non-micaceous clay minerals are conspicuously absent. The sample cannot be classified as a mica because it is hydrated and the particle-size distribution is in the clay size range. A detailed examination of the deposit suggests that it may have value as a reference illitic clay mineral.
Research on Evolution of Clay Minerals and Argillaceous and Siliceous Neoformation
Authors: Millot Georges , Lucas Jacques , Wey Raymond
Published: August 2006

The following recent work is reviewed.

In the Triassic basin of the Jura detrital illite changes into chlorite (chlorite and chloritie mixed layers) toward the middle of the basin.

In the profiles of podzolic soils and podzols, illite and chlorite change, through illite— vermiculite and chlorite-vermiculite stages, into vermiculite.

In Cambrian sandstones of the Sahara two successive diagenetic changes have taken place: early postdepositional kaolinization, and illitization by salt waters.

Neoformation of aluminomagnesian clays in the alkaline sediments of the Eocene basins in Africa produces a sedimentary and geochemical sequence of montmorillonite, attapulgite and sepiolite.

When siliceous neoformation is produced by crystal growth, the growth is regular in the production of quartz, and irregular or hindered in the formation of chalcedony or opal-cristobalite.

Kaolinite has been synthesized at low temperatures in dilute solutions.

Transformations of triphormic clay minerals in the hydrosphere consist of a progressive expansion of layers. Environment controls the equilibrium between interlayer cations and adjacent layers. Siliceous and argillaceous neoformation consists of organization of silica tetrahedrons; this organization depends on the environment and especially on the environmental cations. Transformation by diagenesis is more intense and allows direct passage from illite to kaolinite.
Research Work on Clay Minerals and Argillaceous Rocks in Czechoslovakia
Authors: Konta Jiří
Published: August 2006

The investigation of clay minerals and argillaceous rocks started in the territory of Czechoslovakia as early as the later part of the eighteenth century and has continued up to today. During this long period many interesting results have been obtained. In about 1949 modern laboratory techniques were introduced. Most of the work in this country deals with the mineralogy, petrology, and geology of argillaceous rocks, the chemical composition and physical properties of clay materials which are useful for the purposes of the ceramic, glass, chemical, construction-engineering and mining industries, etc. This paper is subdivided into the following parts: (a) Classical research period; (b) Modern research period; (c) Kaolins (primary); (d) Other argillaceous rocks of sedimentary origin; (e) Bentonites; (f) Laterites and bauxitic rocks; (g) Clay minerals in sedimentary iron ores; (h) Clay minerals in carbonaceous rocks; (i) Clay minerals of hydro-thermal origin; (j) Kinds of apparatus for DTA and gravimetric thermal analysis; (k) Imbibometric study using water and organic liquids; (1) Problems of classification and terminology.
Birefringence of Clay Mineral Complexes
Authors: Greene-Kelly R.
Published: August 2006

The birefringence of complexes of montmorillonite with aromatic liquids depends on the type of liquid, and this fact was used to determine the proportion of expanding layers in some partly expanding minerals. A simple method of assessing samples for the presence of expanding minerals probably could be devised on the same lines.
De Natura Lutorum
Authors: Mackenzie R. C.
Published: August 2006

Despite recent advances in clay mineralogy there is still no generally accepted definition of the terms clays and clay minerals. This problem is discussed from the historical aspect: the similarities of definitions given from the 16th century to the present are remarkable and lead one to consider whether possible simple modifications might not eventuate in some measure of universal agreement. Comparison of nomenclature and classification schemes shows that from the time of Theophrastus to that of Agricola there appears to have been little advance, but a change becomes noticeable by the end of the 18th century, and by the end of the 19th old names, such as porcelain clay, etc., have given place to what are now regarded as names of mineral species or varieties. Only after the 1920’s have satisfactory groupings been obtained, but no internationally acceptable classification has yet been devised. Finally, the various factors operative during clay formation by weathering and diagenesis are discussed, and it is stressed that field and laboratory studies are complementary.
Interlayering of Expansible Layer Silicates in Soils by Chemical Weathering
Authors: Jackson M. L.
Published: August 2006

Interlayering of 2: 1 layer silicates varies as a function of chemical weathering from the simple, homogeneous K or Na interlayers of micas to the heterogeneous systems of mica intercalated with expanded 2: 1 layer silicates. “Frayed edge” type of weathering at dislocation planes of mica is collated with K release and preferential cation-exchange uptake of K relative to Ca by such expansible layer silicate systems; mica islands maintain alignment of the silica sheet cavities, which facilitates recapture of lattice K. Intercalation of the expanded 2: 1 layer silicates with alumina interlayers appears to be a characteristic function of chemical weathering in soils, with the formation of 2: 1–2: 2 intergrades not only of 14 Å spacing but also of swelling 18 Å types that give small 12, 14, 18 Å and higher spacing peaks (along with the 10 Å peak) at 550°C. Interlayer precipitates appear to be characteristic of soil clays, contrasting with “pure” minerals of deposits developed in less “open” environments than those of soils. The “2: 2 lattice building” phenomenon in expansible 2: 1 layer silicates relates to layer charge density and crystal size, and frequently tends to inhibit the formation of free gibbsite in soil chemical weathering so long as there are expansible layer silicates present to become intercalated with aluminum hydroxide—a weathering phenomenon that may be called an “antigibbsite effect”. Accumulation of alumina (possibly with some iron, magnesium, and allophane) as interlayers in 2: 1 minerals of soils is seen as a genetic stage in the 2: 2 → 1: 1 weathering sequence through which kaolinite and halloysite develop in soils.
Negative Charge of Dioctahedral Micas as Related to Weathering
Authors: Cook M. G. , Rich C. I.
Published: August 2006

Negative charge and related characteristics of dioctahedral micas have been investigated by conducting artificial weathering studies on a muscovite from Ontario, Canada, and saprolitic micas from Virginia. Emphasis is given to the relationship between loss of potassium, increase in net negative charge, or cation exchange capacity, and expansion characteristics.

Boiling solutions of acetic acid, sodium chloride and magnesium chloride removed potassium and sodium from a saprolitic mica but produced a negligible increase in cation exchange capacity. Expansion of the mica structure occurred following treatment with salt solutions but not with acid solutions. Boiling solutions of sodium citrate removed potassium effectively, produced marked expansion, and caused a large increase in cation exchange capacity. The small increase in cation exchange capacity resulting from acid and salt treatments is attributed to the hydrolysis of exchangeable aluminum to form hydroxy-aluminum polymeric groups, which can occupy exchange sites but remain non-exchangeable. The results of the sodium citrate tratement are attributed to the complexing of aluminum by citrate, thus releasing the hydroxy-aluminum polymeric groups from exchange positions and permitting an increase in cation exchange capacity.

Molten lithium nitrate treatment of specimen muscovite produced a greater increase in cation exchange capacity than in the case of muscovite separated from soil-forming mica phyllite. The observed difference in charge characteristics, concomitant with the greater expansion of the muscovite, suggest that soil micas and specimen-type micas differ in their alteration tendencies.

When interlayer hydroxy groups are eliminated and account is taken of residual sodium, potassium, and water, dioctahedral micas apparently lose no negative charge on expansion to vermiculite-like minerals.
Weathering of Stone Mountain Granite
Authors: Grant Willard H.
Published: August 2006

The weathering of Stone Mountain Granite (adamellite) forms kaolinite, endellite, allophane and gibbsite of which kaolinite is the most stable. Bulk density ranges from 2.65 in fresh rock to a minimum of 1.48 in saprolite. It is a good index of weathering. Abrasion pH ranges from 5.0 in saprolite to 9.3 in fresh rock, and is directly related to bulk density and the amount of clay mineral. Among the original minerals, biotite is least stable, followed by oligoclase. Residual microcline fragments occur at the base of the B horizon indicating that it is not completely weathered. Muscovite weathers slightly and quartz appears quite stable.

Evidence shows that solution and reconstitution is necessary in the formation of some if not all clay minerals. This is particularly evident in the formation of endellite veins.

Expansion of the rock in the early phases of weathering occurs but does not produce a significant increase in volume.
Characteristics of 14 Å Clay Minerals in the B Horizons of Podzolized Soils of Alberta
Authors: Pawluk S.
Published: August 2006

Recent investigations of soils from widely distributed sites reveal the presence of clay minerals with 14 Å d spacings in the B horizons of podzolized soils in Alberta. The minerals appear to be concentrated in the 2.0–0.2 micron clay fraction, the fraction less than 0.2 micron being comprised primarily of material amorphous to X-ray. Despite the presence of montmorillonite in the eluvial horizon and soil parent material only interstratified minerals of this group appear in association with the 14 Å mineral. Smaller amounts of quartz, kaolinite and illite are also noted in these B horizons.

The data available reveal that the 14 Å mineral is derived from montmorillonite and that formation occurs in situ in the B horizons.

It is apparent from the investigations conducted that weathering of associated feldspars under mildly acid conditions, releases hydrated alumina ions. These ions not only move into the interlayer regions of montmorillonite of fine clay size, where they exist in a discontinuous manner, but are also adsorbed onto the surfaces of these minerals binding adjacent particles into aggregates of coarse clay size. Adsorbed hydrated alumina hydroxy ions in the interlayer region are responsible for the observed 14 Å d spacings.
Solid-Gas Interface in Weathering Reactions
Authors: Wayman Cooper H.
Published: August 2006

Most weathering reactions have been interpreted in terms of the solid-liquid interface. In dry climates or at low humidity, weathering might be initiated or controlled by a solid-gas reaction. The stability of gibbsite and some hydrous borates involves the activity of water vapor; and the stability of azurite depends on a ratio of the partial pressures of both water vapor and carbon dioxide. Much additional work is required on the rates of equilibrium dehydration to contribute to our knowledge of the solid-gas interface in weathering.
Redox Behaviour of Iron in Hydroxylated Silicates
Authors: Addison W. E. , Sharp J. H.
Published: August 2006

The oxidation and reduction of clay minerals, particularly chamosite and nontronite, are compared with those of the amphibole crocidolite. Oxidation is very similar, but differences in behaviour on reduction are described. These differences are interpreted in terms of the different environments of the oxygen atoms in the various structures. Mechanisms of the various processes are discussed in detail.
Montmorillonite-Polyalcohol Complexes: Part II
Authors: Brunton George , Tettenhorst Rodney , Beck Carl W.
Published: August 2006

Oscillating-heating X-ray diffraction was used to determine d-spacings and intensity changes of the (001) diffraction maximum for various combinations of 3 clays, 6 cations and 7 polyalcohols from 20°C to 1000°C under non-equilibrium conditions.

The temperature of collapse of the one layer complex was measured. Analysis of variance of this parameter for a model containing 3 clays, 6 cations and 7 polyalcohols showed that there is a significant difference among cations and polyalcohols but not among clays.

Additional work on one clay, 6 cations and 18 polyalcohols shows that ΔT—the difference in temperature between the collapse of the clay-organic complex and the boiling point of the polyalcohol—is proportional to the length of the carbon chain ; ΔT is also a function of the number and position of the OH groups.

The mean temperatures of final collapse for all polyalcohols are related to the valence of the interlayer cations and inversely related to their ionic radii.

There are two groups of d-spacings for the one-layer complexes. Complexes with polyalcohols having OH groups at the ends of the chain have mean d-spacings between 13.6–13.7 Å, while complexes with polyalcohols with interior OH groups have mean d-spacings of 13.9–14.0 Å.
Hydrothermal Rhyolitic Alteration in the Castle Mountains, California
Authors: Heystek Hendrik
Published: August 2006

X-ray diffraction, differential thermal, chemical analysis and cation exchange data indicate a progressive genesis upon hydrothermal alteration of rhyolitic materials in an extensive fault zone. Kaolinite, a Ca-Mg beidellite, mixed-layer beidellite-hydrous mica and beidellite-vermiculite clay minerals, quartz, cristobalite and feldspar commonly occur in the deposit.

Detailed studies show that the sequence of the 2:1 clay mineral alteration is beidellite-hydrous mica mixed-layer → beidellite-vermiculite mixed-layer → beidellite. This mineralogical change parallels a progressive decrease in the layer charge and amount of fixed K+ present and an increase in exchangeable Ca+ and Mg+ respectively.
Stevensite and Talc—Hydrothermal Alteration Products of Wollastonite
Authors: DeRudder Ronald D. , Beck Carl W.
Published: August 2006

Magnesium-bearing hydrothermal solutions moving along channelways created by faulting in the Willsboro, New York, wollastonite deposit have effected the conversion of wollastonite to layer-lattice silicates. Alteration products sheath faults in wollastonite and may be divided into three gradational but regular zones: (1) least altered (fresh) country rock composed of wollastonite with minor diopsidic clinopyroxene and grossularite-andradite garnet; (2) moderately altered rock rich in montmorillonite; and (3) strongly altered rock composed predominantly of talc.

X-ray diffraction, oscillating-heating X-ray diffraction, electron microscopy, infrared absorption, base exchange, and chemical analyses substantiate identification of the montmorillonitic alteration product, pseudomorphous after wollastonite, as stevensite. Stevensite, a trioctahedral magnesium montmorillonite, has been reported heretofore only in basaltic rocks where it has been formed by the action of magnesium-bearing solutions on pectolite. Pectolite and wollastonite have similar compositions and structures and may be similarly converted to stevensite in a magnesium-rich hydrothermal environment.

Talc, the dominant mineral in the most intensely altered zone bordering the solution channelway, was formed by the continuing action of magnesium-bearing solutions on stevensite. Stevensite has a defect structure, i.e., a deficiency in the total number of ions in octahedral coordination. The addition of magnesium from hydrothermal solutions to the octahedral layer of stevensite converts this mineral to talc, concomitantly freeing interlayer cations and water.

Stevensite is unstable and is converted to talc above a temperature of 275°C at water pressures of 690 bars. It is believed that hydrothermal alteration of wollastonite took place at temperatures near or below 275°C with stevensite forming in the cooler part of the reaction zone, and talc forming from stevensite at slightly higher temperatures nearer the solution channelway.
Variability in “crystallinity” Values among the Kaolin Deposits of the Coastal Plain of Georgia and South Carolina
Authors: Hinckley David N.
Published: August 2006

Quantitative measurement of the relative degree of crystal perfection among 144 samples of Coastal Plain kaolin shows that the deposits are nonhomogeneous with respect to crystallinity and that the hard and soft types can be distinguished at the 0.95 probability level by an analysis of variance. The nonhomogeneity of the deposits and the distinction between the hard and soft types agrees with the results obtained for other properties not reported here. Although on the basis of pulverizing ease there may be a single population with hard and soft end members, in terms of origin the evidence indicates the existence of two distinct clay populations.
Clay Mineral Effects on the Stress-Strain Response of Soils in Direct Shear
Authors: Kondner Robert L. , Vendrell José R.
Published: August 2006

More than one hundred sets of direct shear tests were conducted on soils composed of four reference clay minerals and various combinations of the four clay minerals of the Columbia University Clay Mineral Standards Project (A.P.I. 49) to illustrate with quantitative results the influence of clay mineralogy on the stress-strain characteristics of soils and hence the practical importance of clay mineralogy in soil mechanics. The soils tested consisted of various amounts by weight of Bedford Indiana Halloysite, Mesa Alta New Mexico Kaolinite, Santa Rita New Mexico Montmorillonite and Fithian Illinois Illite prepared with distilled water. The experimental results agree quite well with hyperbolic stress-strain relations previously developed by the author. The Hvorslev strength parameters are written as exponential functions of the clay mineral content and are included in the hyperbolic stress-strain law. The ultimate shear strength of the soils are mathematically expressed in terms of the stress history, confinement, and mineralogy.
Swelling Pressures of Sodium Montmorillonite at Depressed Temperatures
Authors: Yong R. , Taylor L. O. , Warkentin B. P.
Published: August 2006

Swelling pressures of oriented samples of sodium montmorillonite at 10−4 and 10−2 M NaCl in the pore-water were measured at controlled temperatures ranging from 1°C to 23°C. The specially designed apparatus allowed swelling against a movable piston connected to a mercury manometer through which the ambient pressure was applied.

A decrease in swelling pressure with decrease in temperature is predicted theoretically from the Gouy-Chapman theory, taking the variation of temperature and dielectric constant into account. At a salt concentration of 10−4 M NaCl, the measured swelling pressure at 120 Å average interparticle distance decreased from 48 cm of mercury at 23°C to 35 cm at 1°C, while the corresponding calculated pressure decrease was from 48 to 40 cm. While the measured pressures fell below calculated values at higher distances, the influence of temperature remained consistent.

At 10−2 M NaCl, a decrease in measured swelling pressure with decreasing temperature also occurred, but the measured swelling pressures were much higher than those predicted theoretically. Corrections were calculated, based upon the salt concentrations required by the theory to give the experimentally measured swelling pressures at room temperature. These were substituted into the approximate Langmuir solution of the combined Poisson-Boltzmann equation to describe the swelling pressure at 10−2 M NaCl. With these corrections, the calculated swelling pressure at 120 Å average interparticle distance decreased from 30 cm at 23°C to 26 cm at 1°C while the measured pressure decreased from 30 to 23 cm. This agreement between the corrected, calculated pressure and measured pressure held from 100 to 250 Å interparticle spacing.
Studies in Fractionated Montmorillonite Suspensions
Authors: Mungan Necmettin , Jessen Frank W.
Published: August 2006

Four natural bentonites, from Texas, Wyoming, Mexico, and Puerto Rico, have been fractionated by use of a super-centrifuge. The fractions have been investigated for base exchange capacity, apparent density, X-ray diffraction character and gel strengths of their suspensions.

Based on (001) spacings from X-ray diffraction and cation composition from ammonium acetate base exchange data, it was found that upon fractionation, clays of heterogeneous cation composition divide into two groups. Fractions larger than 0.150 micron contain the divalent cations Ca2+-Mg2+, while the finer fractions contain the monovalent cation Na+. Based on indirect evidence provided by X-ray diffraction, particle size fractionation, and gel strength, and correlation of the data with the literature, it is concluded that Na+clays exist as unit layers in suspensions while Ca2+-Mg2+particles are aggregates of a few layers.

Base exchange capacity and density were found to be independent of particle size.

A new structure is postulated and proposed for aqueous montmorillonite gels. This structure, descriptively called “hinge,” comprises clay particles oriented randomly to form a network in which each particle is hinged to other particles through sharing of bound particle-water.
Cation Exchange in Kaolinite-Iron Oxide Systems
Authors: Thomas Grant W. , Swoboda Allen R.
Published: August 2006

Abstbact

Kaolinite, to which iron oxides had been added by heating with FeCl3 solution, was studied with regard to its cation exchange capacity. It was observed that net cations held (cations less anions) varied directly with pH. Cations and anions are removed in equivalent amounts when the clays are washed with water. Removal of exchangeable cations proceeds as the last anions are removed. As a consequence, the negative sites may become saturated with non-exchangeable hydroxy-aluminum ions. To obtain the true CEC of a kaolinite-iron oxide system, it is necessary to estimate the amount of nonexchangeable hydroxy-aluminum by conductometric titration.
The Bentonites of Cabo de Gata (Southeast Spain) and of Guelaya Volcanic Province (North Morocco)
Authors: Vivaldi J. L. Martin
Published: August 2006

Volcanic activity was important in Spain during the second half of the Cenozoic Era. It was closely related to the late kinematic and subsequent periods of the Alpidic orogenic cycle. Manifestations of the volcanic activity are seen in several parts of the Iberian Peninsula, but the main ones were confined to a few rather individualized zones. Cabo de Gata, Cartagena, and Mazarrón show a strong similarity, as does the Guelaya volcanic province, Morocco. The rocks (rhyolites, dacites and andesites) are clearly calcalkaline and, in many places, strong contamination processes have been demonstrated. The eruptions were, at least in part, fissural and fill important fractures, mainly northeast-southwest. They occurred just after the more important folding in the Betic-Riffien orogen. In these regions bentonite has formed by alteration of volcanic material.

The most important deposits are in Sierra of Nijar and Gata (Almería, Spain) and in the Monte Tidinit (Morocco). The Cabo de Gata bentonites are composed mainly of calcic and calcosodic montmorillonites. Palygorskite has been found in some places.

The bentonite of the Monte Tidinit is mainly calcium montmorillonite but some samples contain cristobalite. In Monte Maazza there is also a sedimentary deposit, consisting of a complex mixture of endellite, halloysite, gibbsite, montmorillonite and alunite—probably of hydrothermal origin. Halloysito is the main component: it is accompanied by gibbsite in the bottom layers and by montmorillonite and alunite in the top ones.

The ground clay, after processing by cation exchange or acid activation, is used for several industrial products, such as soaps and detergents, cosmetics and pharmacy; but the main use is for drilling muds, foundry molds, and clarification of mineral and vegetable oils.

All the bentonites are amenable to acid activation but the natural mixture of halloysite and montmorillonite from Monte Maazza gave the best results in tests on lubricating oils at a laboratory scale.

Research still in progress on the rheology of suspensions of the Almeréa bentonite contaminated with electrolytes gave interesting results using several thinner and filter oss control agents.
Kinetics and Mechanisms of Dehydration and Recrystallization of Serpentine—I
Authors: Brindley G. W. , Hayami Ryozo
Published: August 2006

Dehydration and recrystallization reactions of fine and coarse powders and also of massive samples of serpentine under isothermal heating conditions in air are followed by thermobalance measurements and by X-ray diffraction intensities. The rate of recrystallization to forsterite is shown to have an inverse relationship to the rate of dehydration. This result is interpreted in terms of the damage inflicted on the crystal structure of serpentine by the dehydration reaction; the more slowly this reaction occurs, the more readily is forsterite formed as a result of the topotactic relationship between forsterite and serpentine. The surface layers of particles and massive samples of serpentine which dehydrate readily appear to be highly disordered and consequently recrystallize to forsterite very slowly. The corresponding phenomena exhibited by kaolinite are discussed and compared with those by serpentine.
High-Temperature D.T.A. and X-Ray Diffraction Studies of Reactions
Authors: Wahl F. M. , Grim R. E.
Published: August 2006

Several reactions which take place in clay minerals at elevated temperatures were investigated by D.T.A. and continuous high-temperature X-ray diffraction. The combination of these techniques was used to examine the energy changes and phase transformations that occur in kaolinite, halloysite, illite, and montmorillonite at temperatures up to 1450°C.

Diffraction data obtained from these minerals as they were heated are used to interpret the nature of the structural transitions, and new phase developments in two-layer type clay minerals are compared with similar developments in three-layer type clays.

Continuous diffraction is used to detect changes that take place in the firing history of a clay in which small amounts of chemical impurities or other mineralizing substances are present or have been added. Several chemical impurities were added to each of the clays to determine their ability to either enhance or retard structural transition and new mineral development upon firing. The effects which these additives have on predicted structural changes are illustrated and are interpreted in lieu of chemical and structural requirements.
Halloysitic Underclay and Amorphous Inorganic Matter in Hawaii
Authors: Patterson Sam H.
Published: August 2006

Plastic clay deposits underlie peat beds in several swamps on the island of Kauai, Hawaii. These underclays are appreciably different in mineralogical and chemical composition from the associated well-drained weathered rocks (saprolite). The underclay is much higher in silica and lower in iron oxide than the saprolite. The underclay is composed chiefly of halloysite minerals, with minor amounts of gibbsite, anatase, quartz, goethite, and illite. The saprolite is predominately gibbsite, goethite, and hematite, with minor amounts of titaniferous magnetite, anatase, and halloysite minerals. Apparently both the clay and saprolite have formed by weathering from the same type of parent rock and have undergone similar geologic histories; therefore, differences in drainage and the presence or absence of an overlying peat layer appear to be the principal genetic variables.

The underclay and saprolite are believed to contain amorphous gels and allophane because X-ray intensities for many samples are low, and estimated amounts of identifiable minerals are not adequate to account for the whole samples. Attempts to isolate the amorphous materials in samples from Kauai have not been successful, but both an alumina-silica gel and allophane were found in saprolite at one locality on Maui, Hawaii. These materials were collected from the face of a freshly bull-dozed roadcut at a depth of 2 to 6 ft. They occur as veins and as fillings and coatings on vesicles, vugs, and cracks in a dark-brown saprolite closely associated with hard basalt. The allophane is white, and most of it is covered by a clear or light-colored gel. Some of the gel occurs in clear irregular masses ranging in size from microscopic specks to about one-fourth inch in diameter and is similar to a mass of frog eggs or thick gelatin. Some occurs as light-grayish brown, paper-thin laminae that extend along cracks for several inches.

Both the allophane and dried gel are similar in composition, containing approximately 50 per cent alumina and 22 to 26 per cent silica. The close association and similar composition indicate that allophane forms from the alumina-silica gel. Gibbsite and halloysite minerals occur in a manner very similar to that of the allophane and gel, suggesting that these amorphous materials are intermediate phases in the formation of gibbsite and halloysite. This is supported by the small amount of gibbsite present in the dried gel.
Petrogenesis of Bentonites
Authors: Slaughter M.
Published: August 2006

The formation of typical bentonites occurs in two stages. The first stage comprises the development, transportation, and deposition of the volcanic ash, which determines the geometry and structure of the bentonite rock and influences the alteration of the ash during the second stage. The second stage encompasses the alteration of volcanic glass to montmorillonite and other minerals.

The distribution of ash particles in the bentonite beds of Wyoming is satisfactorily explained by a theoretical model based on equations similar to heat flow equations. An extended model, assuming a disk-shaped volcanic cloud containing ash particles, also accounts for the geometrical shapes and geographic variations of the textural parameters of the bentonite beds.

The alteration of Wyoming bentonite ashes to montmorillonite occurred undoubtedly at low temperatures in an aqueous environment. Petrologic evidence indicates that all of the Wyoming ashes and many ashes deposited elsewhere contained sufficient magnesium to form montmorillonite with no addition necessary from without. Also evidence indicates variations of pH of perhaps 5 to 8 made little difference in the alteration products of the ashes.

Laboratory evidence of the processes and products of alteration of ashes to bentonite accord with field observation. With simplifying assumptions, the formation of montmorillonite from volcanic glass may be elucidated from the viewpoint of the stability of montmorillonite with respect to other similar minerals. The results of theoretical calculations of the mineral stabilities will be presented. Three energy parameters will be considered: the Coulomb energy, Van der Waals’ repulsion, and the London energy Thermal motion of the atoms will be taken into account.
Spatial Relations Between Air Bubbles and Flocculated Kaolinite and Dickite
Authors: Okuda Susumu , Williamson William O.
Published: August 2006

The optical microscope revealed that when air-saturated dilute aqueous suspensions of coarse kaolinite and dickite crystals were evacuated, negatively charged bubbles formed on and between the particles, which showed characteristic spatial relations to the bubbles and to each other.

Crystals leached with HCl developed edge-to-face flocculation over a wide acid pH range and presented their edges to the bubbles, indicating positive edge-charges. The addition of Na-montmorillonite reduced the number of particles adhering to the bubbles and impeded the edge-to-face flocculation.

In slightly acid suspensions, the particles became adlineated to form chains linking bubbles together or dependent from them.

At pH <3 or >7 the bubbles retained relatively few particles probably because the negative charge density on bubbles decreased at pH <3, while the crystals lost their positive edge charges at pH>7. At pH>7 crystals were often retained by their basal surfaces.

Crystals saturated with Ca2+ or Pb2+ showed face-to-face flocculation and tended to present their basal surfaces to the bubbles. The relatively large amounts of Ca- and particularly of Pb-clay secured by the bubbles may be associated with the lessened wettability caused by these cations.

The mantles of adherent particles affected the stability of the bubbles, both by preventing the coalescence of neighbors, and by lengthening the diffusion paths for dissolved air passing from smaller to larger bubbles.
Thermodynamics of the Various High-Temperature Reactions of Kaolinite
Authors: Soliman M. R.
Published: August 2006

In spite of the fact that the kaolinite-mullite reaction series had been the subject of extensive investigations since the work of Le Chatelier in 1887, nevertheless many-problems are still remaining. One of the major problems is the interpretation of the first exothermic peak at 980°C.

Based on sufficiently accurate thermodynamic data of kaolinite and its high temperature products, equations were derived, expressing the changes of free energy with temperature for all various possible reactions of kaolinite between 298°K and 2300°K.

The most favourable reaction at 980°C, (1253°K), is that which yields mullite and ß quartz.

The exothermic peak at 980°C is neither due to crystallization of γAl2O3 and SiO2 nor to mullite, γAl2O3 and SiO2 but most probably due to crystallization of mullite and silica. The values of ΔG1250°K are: -40,919, -88,991 and -105,022 cal/mol respectively.
Inorganic pH Dependent Cation Exchange Charge of Soils
Authors: Volk V. V. , Jackson M. L.
Published: August 2006

Sodium hydroxide titration curves were determined on H resin treated montmorillonite, untreated acid and neutral soils of different origins and on the same soils with an H resin treatment. The acid montmorillonite titration curve reveals four buffer ranges corresponding to hydronium ions (range I), monomelic trivalent aluminum ions Range II), and two pH dependent charge ranges. Untreated acid soils contained pH dependent buffer zones governed jointly by the organic fraction, the soil pH, the presence of monomeric trivalent aluminum, and the exchange blocking mechanisms of other cations. Following an H resin treatment, soils containing less than 2 per cent of organic matter exhibited a clearly defined third buffer range (Range III) from pH 5.5 to 7.6. The inflection points are masked in the pH dependent buffer range in soils containing more than 2 per cent organic matter. The presence of added aluminum increased the pH dependent charge in an acidified montmorillonite while added ferric iron slightly decreased it. The natural acid weathering processes in soils result in some blocking of pH dependent charge as in Dodge soil of Wisconsin (KCl pH 4.5). When greater acidity develops, a large pH dependent charge results, as in Coolville soil in Ohio (KCl pH 4.0), and the lime requirement of the soil thus increases greatly.