bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Moisture Tension Measurements: Theoretical Interpretation and Practical Application
Authors: Day Paul R. 
Published: August 2006

AbstractThe tension phenomenon described herein occurs in a wide variety of porous materials, including sands, clays, agricultural soils and porous rocks. When some of the water is removed from a water-saturated porous system, the residual water evidently remains physically interconnected, judging from the fact that water can be transmitted through the system at reduced water content by suction.The removal of water may result in contraction of the system, as in the case of clay, or in the entry of air, as in the case of sand. The liquid phase and the solid phase in contact with it comprise a closely linked force system. Equilibrium can be established between the system at reduced water content and a separate mass of water at reduced pressure through a porous membrane in contact with both.The equilibrium tension required in the external water phase is considered an attribute of the moist, porous, system itself. From this point of view, the tension originates through the combined action of the internal forces of the system in a virtual displacement of water. It follows from this and from the principle of virtual work that the tension is numerically equal to the differential work done by the internal forces per unit volume of water absorbed.The movement of water, under tension, through porous systems represents a special class of flow phenomena in which tensiometers or equivalent devices are required for measuring the hydraulic potential. Flow patterns can be determined in much the same way as in systems characterized by positive hydrostatic pressures, but special attention must be paid to the Darcy coefficient (the capillary conductivity) which varies with the tension.The theoretical conditions for the equilibrium of water in the soil and for emergence from the soil have been developed in terms of the tension and certain applications have been indicated.The phenomenon referred to in the soil science literature as moisture tension has been recognized for almost forty years and has been used as a means of explaining the absorption and movement of water in the soil. It is closely related to osmotic pressure but its mechanism cannot in general be identified with the traditional mechanisms of osmotic pressure. Moisture tension has been observed in wet clay soils and in other finely divided porous systems containing interstitial water, but the phenomenon is not confined to colloidal systems, since moist sand and moist porous rock, such as pumice, show similar effects.
Methods of Preparation and Control of Clay Mineral Specimens in X-Ray Diffraction Analysis
Authors: Milne I. H. , Warshaw C. M. 
Published: August 2006

AbstractThe determination of the clay minerals present in mixtures by x-ray diffraction examination of oriented aggregates on glass slides becomes more reproducible and more conclusive when the relative humidity of the air in contact with the specimen is controlled during the recording of the diffraction pattern. The basal diffraction peaks of expanding and partially expanding clay minerals vary considerably in spacing and intensity with normal variations of relative humidity. These variations may be eliminated by the application of a simple modification to standard x-ray equipment. This modification is useful in maintaining a constant relative humidity at values between <1 and 100 percent. Dry air is used to maintain the effects of dehydration by heat and, in many cases, may be used as a substitute for heat treatment. This is especially true for mixed-layer minerals, which give more intense and more reproducible diffraction effects in dry air. Wet air is better, in many instances, than glycerol or ethylene glycol in resolving the basal reflections of montmorillonite and illite in mixtures. More information can be obtained from preparations of mixed-layer minerals and mixtures of clay minerals by recording the diffraction pattern at various stages of hydration.
Correlation of Paper-Coating Quality with Degree of Crystal Perfection of Kaolinite
Authors: Murray Haydn H. , Lyons S. C. 
Published: August 2006

AbstractSeveral kaolinite samples were selected for x-ray diffraction studies on the basis of their paper-coating ability. The evaluation of the kaolin clay for paper coating was based on a series of empirical tests including viscosity, resistivity, brightness, and particle-size distribution. The crystallinity of the kaolinites was determined by use of x-ray powder diffraction patterns. In all samples that were good paper coaters, the crystallinity was well developed. Other samples which were poor paper coaters either had poor crystallinity, or, if they had good crystallinity, contained montmorillonite. Crystallinity is not a function of the size fraction. Generally, if the crystallinity is good in the raw sample, then the crystallinity is also good in the < 0.25 micron fraction.Suitability of kaolinite clay for paper coating varies directly with the perfection of crystallinity and indirectly with the montmorillonite content. Both of these variables can be determined by use of x-ray diffraction data.
Dehydration of Monoionic Montmorillonites
Authors: Rowland R. A. , Weiss E. J. , Bradley W. F. 
Published: August 2006

AbstractThe dehydration of sodium, potassium, lithium, hydrogen, calcium, magnesium, and manganese monoionic montmorillonites (prepared with ion-exchange columns) and a ver-miculite, was examined by the x-ray powder diffraction oscillating-heating method. The position and intensity of each of the first-order basal spacings were measured at intervals of 5° to 10° C from room temperature to 900°C. Position and intensity measurements were made for the first five orders of the basal spacing of the calcium montmorillonite up to 300° C and compared with computed intensities at these spacings. These data are presented as oscillating-heating x-ray diffraction diagrams showing the intensity change with temperature, with important spacing shifts indicated, and as graphs showing the change in spacing with change in temperature.Like vermiculite, calcium, magnesium, manganese, lithium, and hydrogen montmorillonite have an octahedral coordination of their exchange cation, and upon heating they also pass through two stable hydrates (ca. 14.5 A and 11.5 A). Montmorillonites of the two larger ions, sodium and potassium, have a regular one-water-layer configuration at 12.4 A, which is distinctly different from the 11.5 A hydrate of the smaller ions.The foreshortened oxygen-oxygen approaches of the lower hydrate (11.5 A) may be accounted for by assuming that the exchange ions take up coordinate positions between silica-oxygen and water levels or, alternatively, that some of the silica tetrahedra are inverted.
Effect of Wetting Agents on the Deformation Behavior of Kaolinite-Water Systems
Authors: Ormsby W. C. , Witucki R. M. , Weyl W. A. 
Published: August 2006

AbstractAn experimental technique was developed for studying the deformation properties of kaolinite-water mixtures, and a study was made of the effects of different wetting agents on the deformation behavior of these mixtures. Particular care was taken to minimize physical effects that could be attributed to preferred orientation of clay particles. Evaluation of different compositions was made in terms of stress-strain diagrams obtained by means of a simple compression plastometer test. Auxiliary studies included sedimentation and filtration experiments of kaolinite-water mixtures containing wetting agents.The various classes of wetting agents investigated, viz., anionic, cationic and nonionic wetting agents, were found to affect the deformability of clay-liquid mixtures independently of the surface tension of the liquid phase. As compared with water alone, cationic and nonionic reagents decreased and anionic reagents increased the deformability of clay-liquid mixtures.In general, the sedimentation and filtration properties of kaolinite-water mixtures containing various wetting agents were consistent with the results of the deformation experiments.
Altered Wall Rocks Along vein Deposits in the Central City-Idaho Springs Region, Colorado
Authors: Tooker E. W. 
Published: August 2006

AbstractWall-rock alteration along veins in the Central City-Idaho Springs region, Gilpin and Clear Creek Counties, Colorado, superficially resembles alteration around similar base-metal sulfide deposits, but differs in some details. Meso thermal-type veins of early Tertiary age cut deformed Precambrian metasedimentary, igneous, and metamorphosed igneous rocks; the veins contain pyrite, galena, sphalerite, chalcopyrite, and tennantite as principal constituents and minor gold, silver, and uranium minerals. A spatial zonation of ore minerals relates to distinct stages of ore deposition.Detailed studies show that three of the wall rocks in the area—granodiorite, biotite-mus-covite granite, and biotite-quartz-plagioclase gneiss—are altered to varying degrees and in varying amounts. Clay-mineral formation was a major feature of the process. The alteration sheath around fractures and veins is divided into four gradational but regular zones: (1) Least altered (fresh) rock; (2) weakly altered, hard rock; (3) moderately altered, soft clay-mineral rock—(a) montmorillonite-rich, (b) kaolimte-rich, and (c) illite-sericite-rich; and (4) strongly altered, hard (silicified) rock. The sequence of silicate alteration is believed to relate first to the relative stability of primary mineral structures in the alteration environment, but ultimately to the chemistry of the environment.The host rocks are significant factors in localization of altered mineral assemblages as they supply the requisite elements for argillic-type alteration. Structures of the host rocks and veins play a prominent role in localization of altered rocks and the zoned ore deposits. Coincidence of alteration and mineralization processes may have more spatial than temporal significance.A working hypothesis explaining the geological evidence proposes that most alteration was accomplished by meteoric and/or hypogene solutions before ore minerals were deposited. Later solutions of the pyrite stage may have intensified the early zone 4 alteration assemblage close to the source channels, but base-metal sulfide stage solutions were not competent to impress additional alteration effects. Most supergene alteration occurs close to the surface. Therefore, in these areas alteration zonation does not afford a reliable guide to ore.
Types of Mixed-Layer Minerals from Japan
Authors: Sudo Toshio , Hayashi Hisato 
Published: August 2006

AbstractFrom x-ray studies, mixed-layer minerals can be classified into regular and random types; the former show a long spacing of about 30 A. Certain clays showing strong powder reflections from long spacings have been considered in detail after treatment with ethylene glycol and/or ignition.Kurata clay and Hanaoka clay no. 908, showing 29.6 ± 0.2 A spacing, are composed of the following three kinds of lattices: (a) the usual montmoriilonite lattice with the cell height of 15.4 A (M-lattice), (b) the kaolin mineral lattice with cell height of about 7 A (K-lattice), (c) a new lattice with a cell height of 14 A (G-lattice) which is represented by a regular inter stratification between pyrophyllite and gibbsite layers. In these clays Mand G-lattices form partly a regular mixed-layer structure with a 29.6 A spacing and partly a random mixed-layer structure. Hanaoka clay no. 308, showing a 26.6±0.2 A spacing, is composed of a lattice with cell height of 12 A and a chlorite lattice; these form a regular mixed-layer mineral with the long spacing. A random mixed-layer mineral is found in some so-called acid clays. These clays have very broad basal reflections showing random mixed-layer complexes and having almost equal percentages of kaolinite and montmoriilonite layers. The thermal curves and electron micrographs of these clays are discussed.
Vermiculite as a Member in Mixed-Layer Minerals
Authors: Heystek H. 
Published: August 2006

AbstractX-ray diffraction and differential thermal analysis data are presented for colloid fractions from a soil and shales containing a vermiculite and a montmorillonoid; a chlorite and a vermiculite-chlorite mixed-layer mineral; and a montmorillonoid and a vermiculile-chlorite mixed-layer mineral. The minerals were identified by heating the clay fractions at various temperatures and by treating them with ethylene glycol and/or ammonium chloride.
New data on Sepiolite and Attapulgite
Authors: Mumpton Fred A. , Roy Rustum 
Published: August 2006

AbstractHydrothermal studies have failed to yield synthetic attapulgite or sepiolites in the system MgO-Al2O3-SiO2-H2O. However, the natural minerals can be decomposed to yield mont-morillonoids by mild hydrothermal treatment as low as 200°C and probably as low as 100°C. These data indicate that they are metastable and probably could not have formed at these temperatures.Dry dehydration at 400° and 750°C gave no evidence for the presence of “zeolitic water” in these minerals and failed to establish the existence of “anhydride” phases. The field study of relationships in one sepiolite locality suggests the importance of structural control in the formation of these minerals.
Layer Charge and Interlamellar Expansion in a Muscovite
Authors: White Joe L. 
Published: August 2006

AbstractTreatment of a muscovite (Delamica) with molten lithium nitrate produced a lowering of the layer charge on the mica. By gradual reduction of the density of surface charge the dependence of interlamellar expansion on the attainment of a critical value of about 6.7 × 104 e.s.u./cm2 was demonstrated in a straightforward manner.
Random Interstratification in Organophilic Bentonites
Authors: McAtee James L. 
Published: August 2006

AbstractOrganophilic bentonites prepared by reacting various amounts of n-laurylamine hydrochloride and dimethyldioctadecyl ammonium chloride with bentonite have been studied by the method of Fourier transforms. The transform curves obtained from the x-ray diffraction patterns of these samples show how different numbers of organic layers between clay laminae are produced by different kinds and amounts of organic material added to the clay. It has been found that as the organic material reacts by base exchange with the clay surfaces, the number of organic layers between each two clay platelets increases in a regular and stepwise manner.
Gravimetric Determination of Monolayer Glycerol Complexes of Clay Minerals
Authors: Kinter Earl B. , Diamond Sidney 
Published: August 2006

AbstractGlycerol-treated montmorillonite gradually loses one layer of the normal two-layer glycerol complex upon moderate heating at 110°C, forming a monolayer complex with a sharp x-ray diffraction peak at about 14A. In the presence of free glycerol vapor, this complex is quantitatively stable on further heating. A simple gravimetric procedure has been devised to determine the weight of glycerol retained. The procedure involves addition of a dilute glycerol solution to a dried and weighed sample of clay in an aluminum foil dish, and subsequent oven drying over a glycerol surface until constant weight is attained. The portion of the glycerol retained on external surfaces is assessed by measuring the retention of a replicate sample previously collapsed irreversibly by heating at 600°C or higher.The retention of monolayer glycerol complexes of vermiculite and endellite can be similarly determined. Ethylene glycol forms an analogous series of complexes, and its retention against heating can be measured in exactly the same way. Differential thermal analysis of glycerol- and glycol-treated montmorillonite suggests that both complexes decompose with endothermic reactions at about 300°C.Glycerol retention values were shown to be independent of sample size and to be almost independent of equilibration temperature between 70°C and 150°C. As expected, they are inversely proportional to particle size. Cation saturation affects the values of both internal and external retention for montmorillonites. It is shown that retention is a function of montmorillonite content in a series of artificial mixtures. Glycerol retention values of a number of clay materials are presented.
Hydrothermal Alteration in Some Granodiorites
Authors: Meyer Charles , Hemley Julian 
Published: August 2006

AbstractThe patterns of distribution of the mica and clay minerals resulting from alteration of feldspars are much less regular and well defined in the “porphyry copper” deposits than in the vein deposits such as those at Butte, Montana. There are, however, interpretative problems common to both. Chemically, the destruction of the K-feldspars may be interpreted in the light of laboratory investigations of the system potash-alumina-silica-water at various K+/H+ ratios. The experiments indicate that the K-mica (sericite) stability field lies between the K-feldspar and kaolinite fields. The K-mica field is approximately 1.5 pH unit wide, and its boundaries with K-feldspar and kaolinite are parallel below 500°C. The boundaries slope toward higher K+/H+ ratios at lower temporatures. Thus, considering the. K-feldspar—sericite—kaolinite system of minerals, one might expect field patterns showing a central zone of kaolinite bordered by a zone of K-mica which in turn grades outward into unaltered K-feidspar. Such a pattern is demonstrated by Butte’s inner diekite-kaolinite and sericite and possibly by the zoning at San Manuel described by Schwartz. Alteration of plagioclase introduces additional complications into the distribution patterns of clay and mica minerals, the chief of which is the outer argillic zone so characteristic of both vein and disseminated deposits.
Clay Mineral Stability and Formation During Weathering
Authors: Harrison Jack L. , Murray Haydn H. 
Published: August 2006

AbstractClay minerals undergo significant changes when exposed to weathering agents. Some of these changes were revealed by studying a sequence of samples collected from weathering profiles developed on shales. Illite and chlorite are modified by the development of expandable layers within the illite and chlorite structures. The suggested mechanism of alteration of chlorite is the oxidation and removal of octahedral iron. Chemical analyses indicate that interlayer potassium is removed from illites. Removal of potassium may be accomplished by an exchange reaction between potassium ions and hydronium ions in the environment.The origin of underclays is controversial. In an attempt to shed some light on this subject, three shale-underelay profiles were studied. The changes in clay minerals from shales to underelays are very similar to those in weathered shale profiles. This similarity lends support to the theory that some underelays are products of weathering.
Genesis of Kaolinite in Cretaceous Shales of Central Colorado
Authors: Sand L. B. , Baur Gretta S. 
Published: August 2006

AbstractThe refractory shales of the Purgatoire and Dakota formations in central Colorado were studied to determine the genesis of the kaolinite. The compositions of the shales were similar, with variation only in relative amounts and grain size of the component minerais. The shales consist primarily of kaolinite, subangular to subrounded quartz, and hydro-muscovite, with minor amounts of feldspar, montrcorillonite, mixed-layer clays, and occasional traces of gypsum and zeolites.An inverse relation between the kaolinite and hydromuscovite contents suggests that hydromuscovite was an intermediate mineral in the formation of the kaolonite. Derivation of vermicular kaolinite from feldspar and mica was evident from examination of thin sections.. The thinly banded interfingered lenses of montmorillonite suggest a detrital origin rather than alteration in situ of a volcanic ash to bentonite.Genesis of the kaolinite probably is similar to that proposed recently by Kesler for the Cretaceous clays of Georgia and South Carolina whereby feldspathic sands deposited in a near-shore environment were subsequently weathered to produce residual kaolinite. Winnowing of some of these clays and redeposition in downstream lagoons formed the fine-grained, carbonaceous, “flint” clays, whereas the plastic clays were formed by introduction of detrital montmorillonite.
Acid Dissolution of a Texas Bentonite
Authors: Granquist W. T. , Sumner G. Gardner 
Published: August 2006

AbstractVarious physical properties of an acid-treated Texas bentonite were studied as a function of treatment time. The observed kinetics were pseudo first-order (large excess of acid) and on this basis and the x-ray results a model and mechanism are proposed that are consistent with observed surface area, exchange capacity, and surface acidity changes. A crude estimation of activation energy gave a value lower than that of Osthaus (1956) but of the right magnitude.
Adjustment of Clays to Chemical Change and the Concept of the Equivalence Level
Authors: Powers Maurice C. 
Published: August 2006

AbstractFurther x-ray and chemical work on suspended sediment samples and cored samples from the James River and its estuary support earlier proposals by the author. A chlorite-like clay is forming from weathered illite through a mixed-layer illite—vermiculite-chlorite stage, and some illite is seemingly regenerated to a better illite by potassium fixation.Chemical analyses of interstitial water, hydrochloric acid-leachate, and fused samples offer explanations regarding the chemical changes occurring in clays as composition of the environment changes.Magnesium is adsorbed by clays to a far greater degree than potassium in the marine and brackish environment.The variance between clays found in Recent and ancient sediments is related to and explained by the concept of the equivalence level. It is suggested that K+ is adsorbed preferentially to Mg2+ by clays when they have been buried to a depth that is greater than that of the Mg2+ — K+ — equivalence level; above this level Mg2+ is preferentially adsorbed by the clays.The trifold nature of clay minerals in terms of their origin and distribution is briefly discussed.
Rapid Dissolution of Allophane and Kaolinite-Halloysite After Dehydration
Authors: Hashimoto Isao , Jackson M. L. 
Published: August 2006

AbstractDifferential dissolution in NaOH solution was investigated as a means of purification of clay. It was discovered that a large quantity of allophane and free alumina and silica were dissolved from clay preparations in 0.5 N NaOH solution by boiling for as little as 2.5 min, provided the ratio of clay weight to solution volume was kept less than 100 mg to 100 ml. Reprecipitation of dissolved silica occurred if a more prolonged digestion or higher sample to solution ratio was employed. Also, prolonged digestion in the NaOH solution (for 80 min) dissolved as much as 50 percent of kaolinite (Merck) and 25 percent of Wyoming montmorillonite, but only a small quantity of these crystalline minerals was dissolved during the 2.5 min digestion period. Subsequent dithionite-citrate-bicarbonate treatment removed the released iron. Marked improvement of x-ray diffraction patterns of the clays resulted. This rapid and selective dissolution of allophane and free oxides greatly improves the quantitative analysis of crystalline minerals by conventional methods.After dehydroxylation at 500°C, kaolinite and halloysite became amorphous and also dissolved by the same differential dissolution procedure. Heat-stable (aluminous) montmorillonite and chlorite were only slightly dissolved by this treatment. The selective removal of the 1 : 1 layer aluminosilicates greatly improves the quantitative analysis of the remaining crystalline components of clays by conventional methods.