bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic Studies on Montmorillonites and Nontronite by the Acid-Dissolution Technique
Authors: Osthaus Bernard 
Published: August 2006

AbstractSeveral montniorillonites and a nontronite were digested in hydrochloric acid at constant temperature for various periods of time. Soluble iron, aluminum, magnesium, and in two samples titanium, were determined for each digestion period. Rate of solution curves were obtained by plotting the logarithm of the percent of the residual ions against time. In general, the solution curves were straight lines or curves that could be resolved into two straight lines. From the interpretation of the dissolution curves, it was possible to determine the amount of the ions in octahedral and tetrahedral coordination. For some of the samples, the rate curves also gave the amount of iron and/or aluminum extraneous to the clay lattice. The amount of silicon in the clay lattice was calculated using the experimentally determined octahedral cations, substituted tetrahedral cations if any, and the exchangeable cations assuming 44 charges per unit cell. The distribution of cations in lattice layers indicates that the eight montniorillonites are substantially dioctahedral. Two of the samples showed the presence of iron in tetrahedral coordination while all the samples showed extraneous silicon. The presence of extraneous silicon, iron, and aluminum in purified samples indicates that formulas derived from bulk chemical analyses can be inaccurate.The dissolution of the ions from the clay lattice determined at several different temperatures in one sample and at two acid concentrations in another sample is in agreement with chemical kinetic principles and is a first-order reaction. The rate constant for the acid dissolution reaction increased proportionately with the acid concentration.The activation energies were determined for the solution of iron and aluminum in mont-morillonite from Polkville, Mississippi, and nontronite from Garfield, Washington, using Arrhenius’ Law. In both samples the activation energies (17 to 18 kilocalories per mole) were the same. In the nontronite sample the activation energies were identical for what have been interpreted as octahedral and tetrahedral ions.
Degradation of Hectorite by Hydrogen Ion
Authors: Kerr G. T. , Zimmerman R. H. , Fox H. A. , Wells F. H. 
Published: August 2006

AbstractHydrogen hectorite-water sol was prepared using mixed-bed ion-exchange resins. At 25° C., the rate of change of concentration with respect to time was determined for (a) strong-and weak-acid hydrogen ions; (b) low molecular weight, unassociated silicates; and (c) soluble, unassociated magnesium ion.The experimental data indicate that two consecutive first-order reactions are occurring: (1) strong acid is undergoing a rapid, spontaneous reaction to yield weak acid, and (2) the resulting weak acid is undergoing a slow, spontaneous reaction to yield a neutral clay. The equivalent weight of the strong acid is apparently one-half that of the weak acid. For each milliequivalent of strong-acid hydrogen ion undergoing reaction, one milliequivalent of magnesium ion is released from the crystal lattice. Thus, the acid clay is eventually converted to magnesium clay. In addition, for each milliequivalent of weak-acid hydrogen ion undergoing reaction, one millimole of silica is released from the lattice. Since the release of magnesium ion precedes the release of silica, proton attack is probably occurring at the edges of the crystals. The exact nature of the weak acid is unknown and detailed study would probably be difficult in view of its transitory existence.Freshly prepared acid hectorite contains approximately 40 meq of hydrogen ion per 100 g clay. Therefore, only 3 percent of the total magnesium is released from the lattice. The lattice structure of the resulting magnesium clay is identical with that of natural hectorite as shown by x-ray diffraction.
Interstratification of Layer Silicates in Two Soil Clays
Authors: Schmehl W. R. , Jackson M. L. 
Published: August 2006

AbstractX-ray and chemical analyses were made of two soil clays from Colorado, X-ray diffraction analysis of glycerol-solvated samples oriented in parallel gave poor diffraction patterns. Randomly oriented powder x-ray diffraction analysis showed an intense 4.45 A band indicating the predominance of layer silicates. Total potassium analysis confirmed the presence of illite. Cation-exchange capacity and specific-surface measurements showed that high-charge layer silicates were present. The effect of differential cation saturation and differential heat treatment on the x-ray diffraction patterns of parallel oriented samples suggests interstratification of layer silicates in these soil clays.
Glauconitic Mica in the Morrison Formation in Colorado
Authors: Keller W. D. 
Published: August 2006

AbstractGlauconitic mica occurs as interstitial clay in a bed of fine-grained sandstone, 15 feet thick, in the upper part of the Brushy Basin shale member of the Morrison formation of Late Jurassic age on Blue and Lone Tree Mesas near Uravan, Montrose County, Colorado. This glauconitic mica, similar to other material ordinarily called glauconite, is interesting because the Morrison formation is generally regarded as nonmarine in origin, whereas glauconite commonly forms in a marine environment.The identifying properties of the glauconitic mica are: strong 001 d spacing, 9.97A; very weak 002, 5.01A; strong 003, 3.34A; 060, 1.51A; green color, pleochroic; X and Z indices, approximately 1.578 and 1.600; SiO2 49 percent, Al2O3 18 percent, Fe2O3 13 percent, FeO 1.3 percent, MgO 2.8 percent, K2O 7.8 percent, TiO2 1.1 percent, ignition loss 6 percent, others approximately 1 percent.The glauconitic sandstone is underlain by variegated mudstones about 480 feet thick, which contain montmorillonite (with very sparse relicts of shards), illite, quartz, and also, in several layers, scanty analcime. The Burro Canyon formation of Early Cretaceous age overlies the glauconitic sandstone.This paper discusses alternative origins of the glauconitic mica possible within the framework of an appropriate chemical environment other than, and apart from, one typically marine.
Density and Structure of Endellite
Authors: Pundsack Fred L. 
Published: August 2006

AbstractThe tubular structure that has been proposed for endellite [Al2(OH)4Si2O5·2H2O] will contain considerable space not occupied by the solid phase. Based on the tubular dimensions which have been reported for this material, void space of 30 to 40 percent of the total volume of massive endellite would be anticipated.Experimental determination of the void space in several samples of an endellite specimen by means of density measurements made on water-saturated samples indicates that the massive mineral contains 10 percent or less void space. It is concluded that endellite does not exist in a tubular form.When endellite dehydrates to form halloysite [Al2(OH)4Si2O5] there is no appreciable change in the gross volume of the material. The massive halloysite formed however, contains more than 40 percent void space which is refillable with water. It is hypothesized that endellite may exist in the form of laths with some displacement of the fundamental layer structure. When the endellite dehydrates the laths undergo considerable shrinkage and distortion to give the structures observed in electron micrographs and shadow-cast replicas.
Effects of A Synthetic Resin on Differential Thermal Analysis of Loess
Authors: Sheeler J. B. , Handy R. L. , Davidson D. T. 
Published: August 2006

AbstractSynthetic resins offer a possible method of soil stabilization for roads; aniline-furfural is a synthetic resin showing commercial possibilities. Differential thermal analysis is a useful tool for interpreting the relation between aniline-furfural and the soils that have been stabilized by this resin.Differential thermal curves were run on several loess soils that had been stabilized with varying amounts of aniline-furfural. The clay fraction of these soils had previously been identified as predominantly interlayered illite-montmorillonite minerals. The <2 micron clay fraction varied from 7.4 to 37.0 percent. The thermal curves showed characteristic exothermic organic reactions in the treated soils and relationships were found between the thermal reactions, the percent aniline-furfural, and the percent clay.Double peaks were observed on the curves of all soils containing 2 percent or more of aniline-furfural. The area under the organic double peaks was found to be a function of the percent aniline-furfural. The double peak is believed to be caused by initial burning of readily available aniline-furfural followed by final burning of the remaining aniline-furfural. The release of the resin responsible for the second peak may be due to a breakdown of the clay crystal structure at about 550° C. This indicates a close association of the resin and the clay minerals. The foregoing statement is further strengthened by a linear correlation of distance between peaks and the amount of clay present. Higher aniline-furfural contents increase the area under the second peak; this increase indicates that a larger amount of the resin is being utilized in cementation of grains and is reflected by the mechanical strength of stabilized soil specimens.
Clay Mineral Distribution in the Soil Areas of Arkansas
Authors: Garey C. L. 
Published: August 2006

AbstractStudies on clay types in the soils of Arkansas show differences that are important to the soil properties in the soils of the various regions. Part of the agricultural importance of these soils may be related to their mineralogical composition.The Mississippi River delta area has deposits of soil materials high in montmorillonite-type clay and possessing strong expansion and shrinkage properties. The Arkansas River valley has materials high in illite clay types with montmorillonite. Soils of the Coastal Plain predominate in kaolinite mineral but have sufficient quantities of vermiculite clay to dominate the chemical properties. The Ozark upland soils contain kaolinite and illite in varying proportions.Much of the state is covered with a silt mantle of varying thickness in which the clay mineral composition is mainly that of montmorillonite and illite.
Muscovite Weathering in a Soil Developed in the Virginia Piedmont
Authors: Rich C. I. 
Published: August 2006

AbstractA study was made of the weathering of musco vite-type mica to dioctahedral vermiculite in soils formed from Wissahickon schist in the Piedmont of Virginia. The trend of weathering as a function of depth was most apparent in the soil fractions from 20 to 0.2 microns. X-ray diffraction and chemical analyses indicate loss of potassium and expansion of the muscovite to form vermiculite as weathering proceeded. The amount of interstratified illite-vermiculite relative to vermiculite varied greatly between three soils and was characteristic for each. The widespread occurrence of dioctahedral vermiculite in highly weathered and acid soils suggests the formation of this mineral from commonly occurring muscovite-type micas.
Clay Mineralogy of Pennsylvanian Sediments in Southern Illinois
Authors: Glass Herbert D. 
Published: August 2006

AbstractControversy over the origin of clay minerals in ancient sediments arises because it is difficult to segregate the factors that cause differences in clay mineral composition. A plan of sampling based on four contrasts was used to evaluate some of these factors. Contrasts studied were: (1) permeability contrasts (sandstone vs. shales); (2) environmental contrasts (cyclic sedimentation); (3) weathering contrasts (outcrop vs. core); (4) source area contrasts (orthoquartzite facies vs. subgraywacke facies).The resultant data indicate that clay minerals are both allogenic and authigenic. Allogenic clay minerals are the rule when inheritance from the source area dominates either postdepositional or environmental effect; authigenic clay minerals are found where the environment dominates. Rapid sedimentation favors a dominance of allogenic clay minerals, and major depositional environmental effects are required to produce appreciable change. Some of the factors that influence clay mineral composition include source area contribution, the depositional environment, postdepositional effects after burial, permeability, and postdepositional weathering effects.
Clay Minerals at a Pennsylvanian Disconformity
Authors: Dalton Jane A. , Swineford Ada , Jewett J. M. 
Published: August 2006

AbstractAt the Desmoinesian-Missourian disconformity in southeastern Kansas a fossil soil zone is recognized by variations in clay mineralogy in the uppermost Desmoinesian Holdenville shale, which underlies basal Missourian Hepler sandstone. The clay fraction of the overlying basal Missourian Hepler sandstone contains kaolinite, slightly hydrated illite, quartz, and vermiculite. Chlorite (rather than vermiculite) is present in shaly portions of the basal Hepler sandstone. Clay-size minerals of the typical Holdenville shale (marine) are predominantly illite, chlorite, quartz, feldspar, and a very small quantity of kaolinite. The clay-mineral assemblages in samples from the upper part of the Holdenville shale indicate hydration of illite, sporadic increase in kaolinite, possible decrease in feldspar, and progressive modification and destruction of chlorite resulting in production of mixed-layer minerals.
The Dehydration of Tobermorite
Authors: Taylor H. F. W. 
Published: August 2006

AbstractTobermorite [Ca4 (Si6O18H2)Ca·4H2O] is a hydrated calcium silicate mineral with a layer structure which in some respects resembles that of vermiculite. Its dehydration has been studied using single crystals from Ballycraigy, N. Ireland. The three most frequently encountered hydration states are characterized by basal spacings (d002) of 14.0, 11.3 and 9.35Å. Dehydration to the 9.35Å state is complete by 300°C and is accompanied by a stacking change so that the pseudo-cell (a 5.58, b 3.66, c 18.70Å) becomes A-face centered. The 9.35Å structure persists up to 700°C, by which temperature all the water has been expelled, and there is some evidence that interlayer Si-O-Si bonds are formed to an increasing extent as the temperature rises.At about 800°C, the 9.35Å hydrate changes to β-CaSiO3 twinned in two orientations. The b-axis of the 9.35Å hydrate becomes b for both orientations of the product, and the (201) planes of the latter are formed parallel to the (101̄) and (101) planes of the original material. The mechanism of the change is discussed and is compared with some other transformations occurring under similar conditions. An orientation-determining step is suggested in which the principal effect is a migration of silicon atoms or ions, the calcium—oxygen skeleton remaining relatively undisturbed.
Studies on the Size and Shape of Clay Particles in Aqueous Suspension
Authors: Kahn Allan 
Published: August 2006

AbstractThe size and shape of clay particles in aqueous suspension have been determined by means of five experimental techniques—electro-optical birefringence, ultracentrifugation, viscometry, optical transmission and electron microscopy. Five clay minerals—montmorillonite, illite, hectorite, nontronite and attapulgite—each subdivided into five size fractions, were studied. The average particle dimensions in each fraction are tabulated.An evaluation of the experimental techniques is presented. It is concluded that for a preliminary survey of the particle size and shape of clay minerals the technique of electron microscopy is best. However, once a model for the particles is obtained, a combination of the techniques of electro-optical birefringence and viscometry becomes more useful in characterizing the size and shape of the particles in suspension.
Water-Vapor Adsorption on Clays
Authors: Johansen Robert T. , Dunning H. N. 
Published: August 2006

AbstractThe distinctive response of clay minerals to water indicated that it should be possible to determine the water sensitivities of sedimentary rock samples directly by water- vapor adsorption measurements. Therefore, the adsorption of water-vapor by standard clay samples and by core samples from oil-producing formations has been investigated.Water-vapor adsorption isotherms of the montmorillonite and kaolinite samples are characteristic of the clay type and serve as an aid in their identification. The illite isotherm was intermediate between those of the other two types.Water-vapor adsorption by core samples from oil-producing formations varied with the contents of swelling clays and with water-sensitivities as indicated by previous x-ray analyses and permeability studies. Core samples containing montmorillonite clay adsorbed water vapor strongly and exhibited typical adsorption—desorption hysteresis. Correlations of nitrogen and water-vapor adsorption studies with clay analyses and permeability measurements show that the water-vapor adsorption method is a promising means for the direct measurement of the water sensitivities of sedimentary formations.
Water-Vapor Sorption on Kaolinite: Hysteresis
Authors: Martin R. Torrence 
Published: August 2006

AbstractDetailed water-vapor sorption measurements were made on Li, ISTa, K, Cs and Mg kaolinite at 25°C. When desorption is started from P/P0 near saturation, all ionic modifications show reversible hysteresis. The size and P/P0 range of the hysteresis loop varies with the nature of the exchangeable ion and sample history.No hysteresis occurs on Li and K kaolinite when desorption is started at P/P0 < 0.8 which along with other data indicates that Li and K exchangeable ions are not truly hydrated below P/P0 = 0.8. The hysteresis for all ionic modifications is traced to hydration of the exchangeable ions. The apparent anomalous position of Li and K ionic hydration is attributed to control of hydration of exchangeable ions by the difference between the hydration energy of the ion minus the specific adsorption energy of the ion for the clay. This difference must be positive before true ionic hydration occurs.A molecular model for sorption is postulated in which sorption is assumed to take place at specific sorption sites upon the clay surface. The energy of sorption at different sites is believed to be different and also to be a function of the hydration state of the exchangeable ion. By the use of the proposed model and the detailed sorption data, hydration of the different exchangeable ions as a function of the relative vapor pressure can be obtained. The sorption model also predicts phase changes in the sorbed film at certain relative pressures. These calculated phase changes agree very well with phase changes indicated from Jura-Harkins’ plots of the experimental data.
Stability and Decomposition Products of Hectorite
Authors: Sand L. B. , Ames L. L. 
Published: August 2006

AbstractThe Hector, California, bentonite has been found unusual in many respects, and its thermal stability under hydrothermal conditions is no exception. It is important that the stability of this bentonite be known, as it is an end member of the saponite series with all cation positions, excluding interlayer, in the structure filled. The information is applicable to studies of wall rock alteration in which saponites occur as alteration products associated with ore deposition.This saponite has an upper thermal stability limit of 750°C, at 15,000 psi water pressure, at which temperature it decomposes. The only products observed were talc and vapor; above 780°C the decomposition products observed were anthophyllite and vapor. Syntheses on the hectorite composition corroborate these decomposition temperatures and products.Hydrothermal treatment at temperatures below about 450°C produce no change in the x-ray diffraction pattern of hectorite: on drying, the lattice collapses to a basal spacing (10–12Å) approaching that of mica, and with ethylene glycol expands to 17Å. However, after hydrothermal treatment above this temperature and to decomposition at 750°C, the hectorite, after subsequent cooling, collapses on drying at 110°C or less to 9.4Å, but expands as before to 17 Å with glycol saturation. Without the glycol treatment the resulting material could be mistaken for talc and considered the decomposition product of hectorite at the higher temperatures. This behavior also occurs using the synthetic hectorite but does not occur when using synthetic or natural saponites containing aluminum.For comparison, the relative stabilities of some dioctahedral and trioctahedral layered minerals are given to show the consistently higher stabilities for the minerals whose octahedral positions are filled.
Surface Area Changes of a Vermiculite by Acid and Thermal Treatment
Authors: Lopez-Gonzalez Juan de D. , Cano-Ruiz Jesus 
Published: August 2006

AbstractA Vermiculite from Beni-Uxera, North Africa, was refluxed with HC1 solutions of various concentrations to determine the effect of such a treatment on its surface area. The treated vermiculite was analyzed for “free” SiO2 and by x-ray diffraction, and the refluxing solutions were analyzed for the cations removed from the vermiculite. Surface areas were determined by means of adsorption isotherms of n-butane at 0°C.The surface area of the acid-treated vermiculite increases with increase in concentration of the acid. Heating of the acid-treated samples or the natural samples decreases the surface area.The increase in surface area by acid treatment is due to destruction of the vermiculite and its conversion to a “free” form of SiO2 which possesses a large surface area. x-Ray analysis indicated that this “free” SiO2 was not present in the interlayer positions of the crystal lattice of vermiculite.
Pretreatment of Soils and Clays for Measurement of External Surface Area by Glycerol Retention
Authors: Kinter Earl B. , Diamond Sidney 
Published: August 2006

AbstractHeat treatment at 600°C has been the usual procedure for irreversible collapse of expanding clay minerals prior to determination of the external surface area of clays and soils by glycerol retention. Evidence is presented showing that this treatment is unsuitable since it greatly reduces the external surface area of certain minerals and increases that of others. Saturation with the triethylammonium cation avoids these difficulties and produces an effect analogous to the collapse of expanding minerals by stabilizing their basal spacing at 13.3 Å. This prevents the entrance of glycerol between the unit layers and confines the sorption to the external surfaces of the particles.
Quantitative X-Ray Determinations of Some Aluminous Clay Minerals in Rocks
Authors: Schultz Leonard G. 
Published: August 2006

Abstractx-ray diffraction traces were made of oriented aggregates of artificial binary mixtures containing approximately equal, weighed amounts of samples of illite, montmorillonite, mixed-layered combinations of illite and montmorillonite, and of kaolinite samples having different degrees of crystallinity. Measurements most suitable for quantitative purposes were obtained from the 7 Å kaolinite peaks and from the 10 Å peaks of illite and collapsed montmorillonite and collapsed mixed-layer clay. In this paper the sum of five height measurements at half-degree intervals across the peak are considered to be a measure of the area of the peak. Fireclay-type kaolinites gave 7 Å peak areas about equal to the area of the 10 Å peak of an equal amount of illite, montmorillonite, or mixed-layer clay, whereas well-crystallized kaolinites gave 7 Å peak areas generally about twice that of the 10 Å peak of an equal weight of the illite-montmorillonite minerals. Kaolinite samples having intermediate degrees of crystallinity gave 7 Å/10 Å peak area ratios intermediate between 1: 1 and 2:1. The shape of the 7 Å kaolinite peak was used to evaluate the crystallinity of the kaolinite.x-ray diffraction characteristics of the chlorite minerals from the different groups of sedimentary rocks studied vary considerably, and no uniform method has been found for their evaluation.