bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Microscopy as a Method of Identifying Clays
Authors: Bates Thomas F.
Published: August 2006

Electron microscope studies show that most of the clay minerals have
morphological characteristics which can be effectively used to aid in their
identification. In addition, detailed studies at high magnification have
provided structural information not obtainable by other means.

In the kaolinite group each of the common minerals has a clear-cut and
diagnostic morphology. However, much more work is needed on flint clays and
the kaolins in soils before the same can be said of these varieties.
Continued study of halloysite reveals significant details pertinent to the
form and structure of the tubular crystals.

Illites from different sources show interesting differences in form
which reflect variation in the degree of crystallinity. An illite from the
Ordovician Oswego formation shows an unusual development of narrow to broad
lath-shaped crystals. Except for lower content of iron and magnesium the
material has all the characteristics of other illites. The thinnest laths
are of the same order of thickness as the flakes of more common illites.
Certain mixed-layer minerals are identical in morphology with some varieties
of illite.

The minerals of the moutmorillonite group have been the most difficult
of the clay minerals to characterize on the basis of morphology. The
lath-shaped crystals of certain beidellites, sauconite, nontronite, and
hectorite are diagnostic. The metal shadowing technique shows that many of
the laths approach one unit cell in thickness.

The morphology of many montmorillonites is dependent upon the mode of
sample preparation. The replica method offers a means of studying clay
particles in their natural state but this technique is still in the early
stages of development as it relates to the clay minerals.
Differential Thermal Analysis of Clays and Carbonates
Authors: Rowland Richards A.
Published: August 2006

Differential thermal analysis (DTA) began soon after the development of
the thermocouple. It has progressed through the systematic development of
better equipment and the cataloguing of typical DTA curves for a variety of
materials until good technique now requires control of the composition and
pressure of the furnace atmosphere as well as consideration of the
thermodynamics and kinetics of the reactions involved. Although differential
thermal analyses have been made for many materials, the major applications
have been concerned with clay and carbonate minerals.

In DTA curves for clay minerals the low-temperature endothermic loop
associated with the loss of water, and the high-temperature exothermic loop
accompanying the formation of new compounds, are changed in shape,
temperature, and intensity by the kind of exchange cations. The
midtemperature-range endothermic loop has a temperature dependence on the
partial pressure of water in the furnace atmosphere.

For the anhydrous normal carbonates the dissociation temperature and its
dependence on the partial pressvire of CO2 are in the
decreasing order Ca, Mg, Mn, Fe, and Zn. The lower temperature loop of
dolomite, the reaction for which must be preceded by an internal
rearrangement, is independent of the pressure of CO2
but may be shifted to a lower temperature by prolonged fine grinding which
accomplishes a similar rearrangement.
Role of Physical Properties of Clays in Soil Science
Authors: Page J. B.
Published: August 2006

The physical properties of clay are of extreme importance in soil
science. Plant growth, and hence crop production, within any environmental
condition is largely controlled by soil structure which results from
reactions involving clay. The active clay material in soil, particularly in
combination with small amounts of organic matter, exerts a tremendous effect
on soil properties. This effect may be on structure (the arrangement of soil
particles), or on consistence (the response of the soil to mechanical
manipulation). Where structure is favorable soil grains are clumped together
into effectively larger aggregates so that soils have a more open
arrangement and water and air can move freely and roots function normally.
Where structure is unfavorable, soils tend to be heavy and impervious, and
both the physical and chemical properties of the soil become unfavorable for
plant growth. Soils which are low in clay, such as sands and silts, exhibit
a rather narrow range over which physical properties can change and may be
unfavorable for plants, being droughty and lacking in fertility. Structure
of soil may change through action of natural forces, management practices,
or cropping systems, and it is of great importance that we understand how
structure affects plants, and how it is formed and stabilized by reactions
involving clay.

Combination of clay with relatively small amounts of certain organic
compounds greatly changes the physical properties of the system and the
nature of the combination and the mechanics of the soil structure-forming
process are but little understood. Such changes greatly affect soil
consistence and soil-water relationships as well as soil structure. The
problem is made difficult since the results of any particular combination or
change in clay characteristics must be interpreted not in terms of the clay
system alone but in light of the resultant effect on the complex and dynamic
system which constitutes a soil. Solution of such problems, however, may be
of great importance to our future ability to produce food and fiber
abundantly and efficiently from our limited soil resource.
Importance of Clay in Applied Soil Mechanics
Authors: Hveem Francis N.
Published: August 2006

Interparticle friction is the principal property which permits soils and
granular materials to resist load without formation. Dry soils of virtually
all types are highly stable. The suitability of soils for engineering
purposes depends largely upon their ability to remain in place and support
whatever loads may be placed upon them, either by a permanent engineering
structure or by transient vehicle loads. A study of the properties which
distinguish the more satisfactory from the less satisfactory soils indicates
that in the majority of eases clays are detrimental to stability. It is
apparent that wet clay has the effect of a lubricant in diminishing the
natural resistance due to friction that would otherwise exist. It is
necessary that the civil engineer responsible for construction of any form
of earth work should be informed not only concerning the Quantity of clay
minerals that are present but also about their nature and their potential
influence on the engineering properties of the soil.
Genesis of Clay Minerals in Some Pennsylvanian Shales of Indiana and Illinois
Authors: Murray Haydn H.
Published: August 2006

Shales of marine, brackish-water, and nonmarine origin, collected from cyclothems of Pennsylvanian age, were analyzed chemically and mineralogically. Clay mineral identifications were accomplished using x-ray diffraction and differential thermal analysis techniques. Summations of the structure amplitudes of the individual clay minerals formed a basis for semi-quantitative ratios between illite and kaolinite-chlorite. Illite was found to be enriched in the marine shales. The origin of the authigenic clay minerals in the shales is discussed from two aspects. The first and probably the more correct uses the thesis that the ultimate clay mineral is built up from a skeletal aluminum-silicate structure; the second discusses the origin of the clay minerals from a purely colloidal point of view. Trace element determinations, pH values, and pipette analyses are also included as a part of this study.
Clay Diagenesis in the Chesapeake Bay Area
Authors: Powers Maurice C.
Published: August 2006

The rivers of the Chesapeake Bay area carry in suspension predominantly a well formed to degraded illite with minor amounts of kaolin and accessory degraded chlorite. Montmorillonite is rare.

Electron microscope photographs of suspended and bottom sediment clays in the James estuary indicate a decrease in floccular size and an increase in crystal size with increasing salinity.

A chlorite-like clay is forming in the Chesapeake Bay estuaries. Its thermal stability increases with increase in the salinity of the environment and with depth in the sediments. This material seems to arise from the diagenesis of degraded illite in the Chesapeake Bay area, but it has also been observed to result from diagenesis of a montmorillonoid in the Atchafalaya region of the Gulf Coast.

The geochemical relations of chloride, sodium, calcium, potassium, and magnesium in the clays of the James estuary support the hypothesis that chlorite is forming in the estuarine and marine environment.
The Decomposition Products of Anorthite Attacked by Pure Water at Elevated Temperatures and Pressure
Authors: Frederickson A. F. , Cox J. E.
Published: August 2006

The behavior of anorthite under the test conditions is similar to that of other feldspars and quartz. The solubility of anorthite in pure water was measured at 300 bars pressure between 200° and 350°C. Under these conditions, anorthite not only partially dissolves, but also disintegrates by shedding small particles of crystalline material which forms, with matter in true solution, a nonhomogeneous suspension. Two zeolites (afwillite and xonotlite) develop at the higher temperatures. Their stability is determined by the CaO:SiO2 ratio of the solution.

The anorthite fragments react with the solution. They maintain their identity although their composition and structure gradually change over a wide temperature range. Possibly the zeolites inherit their structure from the altered anorthite. It is almost certain that xonotlite inherits its structure from afwillite.
The Application of Phase Equilibrium Data to Certain Aspects of Clay Mineralogy
Authors: Roy Rustum
Published: August 2006

The recent interest in the determination of the phase diagrams for many systems involving water as one component has been in those systems which are of greatest importance to clay mineralogy.

The importance of both published and more recent work on synthesis of the clay is demonstrated in the ability to prepare chemically pure, mineralogically homogeneous kaolinites, montmorillonites, micas, and chlorites. The stability and identification of the clay minerals are discussed in relation to some of the major problems of clay mineralogy. Some of the chief objections to data obtained by the usual hydrothermal techniques are treated at length.
The Variations of Wyoming Bentonite Beds as a Function of the Overburden
Authors: Williams F. J. , Elsley B. C. , Weintritt D. J.
Published: August 2006

The colloidal properties and base-exchange characteristics of five deposits in four different areas were determined. The variations of the clay were, in general, a function of the amount of overburden and have been related to that dimension.

From the standpoint of appearance, two types of clay were found in these areas. The highest grade clay has a yellow color whereas the other type, a blue clay, is customarily found to be of lower grade.

Differential thermal studies of the yellow and blue clay, when correlated with variations in colloidal properties, strongly suggest that the change from blue to yellow is due to oxidation of iron.

The primary cause for variation in properties is due to the Na/Ca ratio in the exchange positions regardless of whether the iron in the clay is in the ferrous or ferric state. Examination of purified clays indicates that the exchangeable base ratio of the field bentonites lies in a zone of instability. This zone occurs when the divalent ions amount to 40 to 60 percent of the base-exchange capacity.
Mineralogy of Soil Profiles: Iredell and Durham Soils from the Piedmont Province of North Carolina
Authors: Rolfe B. N.
Published: August 2006

A comparative study of two soil profiles derived from a biotite-granite and from a metagabbro in the Piedmont Province of North Carolina was made. Intensive weathering of the granite has yielded a soil (Durham) with a clay fraction composed of a kaolinite-halloysite intermediate, mica, and quartz. Restricted weathering of the metagabbro has resulted in a soil (Iredell) with a clay fraction composed of a complex assemblage of chlorite, beidellite, vermiculite, interlayered talc-like minerals, and quartz.

The data indicate that the Durham soil is derived from the severe alteration of a granite and that it represents an advanced stage in soil formation. The Iredell soil has been derived from the less active weathering of a metagabbro and represents a retarded, youthful stage in soil formation. The clay mineral assemblage of the Durham is that of a comparatively stable end product of weathering; that of the Iredell is indicative of a complex, unstable early stage in weathering.
Studies of the Clay Fraction of Southwestern Iowa Loess
Authors: Davidson D. T. , Handy R. L.
Published: August 2006

This paper presents data on clay-size material in the loess of southwestern Iowa. Most of the loess samples studied are Wisconsin in age. Regional distribution of clay-size material in the loess is discussed, and data are given on the modes of occurrence of clay in the loess. The following test methods were used to study the clay fractions of selected loess samples: Mechanical analysis, differential thermal analysis, cation-exchange determinations, refractive index determinations, and x-ray diffraction techniques. These tests indicate a uniformity in clay-mineral composition, with montmorillonite and illite group minerals predominating. Clay contents from mechanical analysis are correlated with various properties of the loess; in most cases the properties appear to be linear functions of the clay content. The plastic limit is discussed in detail.
The Use of Salted Pastes of Soil Colloids for X-Ray Analysis
Authors: Barshad Isaac
Published: August 2006

A new technique for the x-ray analysis of soil colloids is proposed based on the finding that the interlayer swelling of montmorillonite persists in the presence of salt solutions and that the x-ray reflection representing the d(001) spacings becomes intensified in salted gels. The technique consists in flocculating the colloid from a suspension with sodium chloride, removing the “free” Fe2O3, Al2O3, and SiO2 by means of a solution of sodium citrate and sodium hydrosulfite, separating the cleaned colloid from the solution as a salted paste, and as such subjecting it to x-ray analysis. The method is not only more rapid than other recommended methods for x-ray analysis of soil colloids, but also — and which is of the utmost importance — yields a much more accurate picture of the mineralogical composition, particularly with respect to the content of the mica and the montmorillonite-type clays.
Some Analyses of Soil Montmorin, Vermiculite, Mica, Chlorite, and Interstratified Layer Silicates
Authors: Jackson M. L. , Whittig L. D. , vanden Heuvel R. C. , Kaufman A. , Brown B. E.
Published: August 2006

Analyses were made of 12 clay fractions and one silt fraction taken from 10 different soil horizons and clay deposits. The analyses presented were selected to represent a wide variety of analytical problems with materials containing 2:1 layer silicates, 2:2 (chlorite) layer silicates, varying amounts of 1:1 layer silicates, and in some cases with appreciable amounts of quartz, feldspars, gibbsite, hematite, magnetite, and (or) anatase.

The analyses were performed by x-ray diffraction, specific surface, integral heating weight loss, and elemental analyses. The x-ray diffraction analyses included both wedge-powder (film recorded) and oriented (Geiger counter recorded) techniques. Vermiculites of soils were found to vary in the degree to which K-saturation would close the interlayer space, but vermiculite is established by: (a) a 14 A spacing when solvated (even with glycerol); (b) closure of the interlayer spacing on heating to 500° C; and (c) an interlayer surface of about 800 m2 per gm. In the absence of adequate criteria, vermiculites can be mistakenly identified as chlorites.

The data obtained from the various techniques were combined by a system of allocation so that the minerals reported represented a unique fit of all the data. The specific surface measurement, including the measurement of interlayer surface, is a key criterion in the allocation. Interstratified (“mixed layer”) layer silicates are determined as the individual component minerals.

The beidellite of Iron River and Putnam soil clay finer than 0.08 microns is extensively interstratified with chlorite, mica, and vermiculite. No discrete x-ray crystalline zones of any of the latter three minerals were observed, but a 19.6 to 19.2 A spacing may be indicative of a superlattice of these materials and beidellite with mica and chlorite at the electron density nodes. A titaniferous ceramic clay contains 43 percent mica (as determined by allocating the 5.03 percent K2O to muscovite), 20 percent kaolinite (water loss in 300–525°C range), 21 percent TiO2 and 17 percent of other constituents (by elemental and surface analysis). This occurrence of the full complement of K2O in clay micas (both biotite and muscovite type) is general for the various clays examined, when the interlayer surface is calculated to halloysite, vermiculite, and montmorin. A general occurrence of inter-stratification of layer silicates is proposed.
Base-Exchange: An Analytical Tool for Mixed-Layer Aggregates
Authors: Ormsby W. C. , Sand L. B.
Published: August 2006

Base-exchange determinations were made on selected clays of the montmorillonite-illite group to test this method as an analytical tool for the analysis of mixed-layer aggregates. The relatively rapid manganese method developed by Bower and Truog was used and its precision determined on monodisperse, monomineralic fractions and monodisperse fractions of prepared mixtures of illite and montmorillonite. The particle size range 1-0.25 micron was chosen for all determinations exclusive of those on bulk samples.

To establish end members, determinations were made on a series of illites, finegrained muscovite and both natural and synthetic montmorillonites.

In order to test the validity of this method, determinations were made on mixed-layer aggregates on which illite-montmorillonite percentages had been determined by other workers using x-ray techniques and chemical analysis.
Evaluation of Methods for Quantitative Analysis of Halloysite-Kaolinite Clays
Authors: Sand L. B. , Ormsby W. C.
Published: August 2006

A number of methods were tested for their applicability to the problem of determining the content of halloysite in kaolin clays. These analytical methods included the thin-section point-count technique, base-exchange determinations, electron microscope techniques and infra-red absorption spectra differences.

Base-exchange determinations were made on a number of monodisperse fractions of pure halloysites and kaolinites. Consistent values of 12 meq/100 g were obtained for the halloysites and 4 meq/100 g for the kaolinites in the size range 1-0.25 micron.

Electron micrographs were taken of prepared homogenized mixtures and counts made of the two morphologically different varieties. Application of this technique to several natural halloysitic kaolins, of which the proportions were known by DTA methods, gave good correlative results.

The thin section method gave very good results on residual clays where the kaolinite occurs as vermicular aggregates.

Infra-red absorption spectra were run by associates on prepared mixtures and the differences were sufficiently marked to give semi-quantitative results.

These four techniques are evaluated with respect to accuracy and application and are compared with other reported techniques.
A Mixed-Layer Kaolin-Chlorite Structure
Authors: Brindley G. W. , Gillery F. H.
Published: August 2006

A mineral of chlorite-type composition, classified as a daphnite, is shown to give a series of basal x-ray reflections which are incompatible with the normal chlorite structure. Fourier analysis indicates a modified distribution of Si and O atoms. A model is suggested in which some Si atoms are displaced and linked to the adjacent brucite-type layer, producing in effect kaolin-type structural units within the chlorite structure.
X-Ray Study of a New Variety of Serpentine (Ortho-Antigorite)
Authors: Brindley G. W.
Published: August 2006

X-ray powder data show an ortho-hexagonal cell containing two structural layers. Close similarity with the data for amesite suggests a similar disposition of the layers within the unit cell. Evidence for a superlattice parameter is obtained indicating a structure similar to that discussed by Aruja and by Onsager.
The Structure of Chloritoid
Authors: Brindley G. W. , Harrison F. W.
Published: August 2006

A summary is given of a structure analysis of chloritoid. The structure contains continuously linked octahedral sheets cross-linked by discrete SiO4 units. Comparisons are made with mica structures and with corundum.
Electron Micrographic Studies of Clays
Authors: Taggart M. S. , Milligan W. O. , Studer H. P.
Published: August 2006

In order to provide a set of reference photographs to be used in identification studies, electron micrographs at relatively high magnification (40,000 to 132,000 diameters), together with some electron diffraction patterns, have been obtained of a group of (a) kaolinites, (b) halloysites, and (c) South Texas outcrop soil samples. Some of the kaolinites consist of well-formed hexagonal crystal plates with edges still sharp at a magnification of 132,000 diameters. Other kaolinites consist of irregular, relatively thin crystal sheets, which may be bent or folded. In one instance it has been possible to demonstrate that the average thickness of the sheets is only 10 Å. At high magnification the halloysite clay minerals exhibit a structure consisting of rolled sheets, rather than hollow rods. In some cases, it is evident that several separate crystal sheets are coaxially rolled to form multiple concentric hollow tubes. In the South Texas outcrop samples, the morphology is very complex, as the samples do not consist of one uniform type of particle. Matted sheets composed of interlaced bundles of lath-like particles have been observed. These oriented particles exhibit typical “fiber” type electron diffraction patterns. Kikuchi lines were observed in a thin quartz crystal plate, examined for comparative purposes.
Studies of some Vermiculite-Type Clay Minerals
Authors: Hathaway John C.
Published: August 2006

X-ray and electron-diffraction studies, and differential thermal analyses of the clay fraction of some soils from Virginia, New Jersey, and Wisconsin indicate an abundance of minerals resembling vermiculite. Measurements of the 060 spacing for these minerals give values lower than those obtained for trioctahedral vermiculites. It is suggested that the minerals studied are dioctahedral forms, which have resulted from the weathering of muscovite-type micas.
Effect of Exchangeable Cation on X-Ray Diffraction Patterns and Thermal Behavior of a Montmorillonite Clay
Authors: Mielenz Richard C. , Schieltz N. Cyril , King Myrle E.
Published: August 2006

A stratum of bentonite in the North Park (?) formation near Granby, Colorado, is composed largely of a dioctahedral Ca-montmorillonite whose formula is calculated to be $\left( {A{l_{2.84}}F{e_{0.50}}M{g_{0.72}}M{n_{0.04}}} \right)\left( {\mathop {A{l_{0.40}}S{i_{7.60}}}\limits^{\mathop \uparrow \limits^{{X_{0.86}}} } } \right){O_{20}}{\left( {OH} \right)_4}.$

Na+, K+, Li+, H+, NH4+, Ca++, and Mg++ modifications were stored at 52 percent relative humidity and at 105° C-110° C. Results of X-ray diffraction, differential thermal, and thermal balance analysis depend upon the exchangeable cation and prior treatment. As with many montmorillonoids, d(001) = 22.7−30.1 Å under room conditions; ao = 5.20 Å and b0= 9.00 Å. The (001 ) interference indicates that the unit cell typically includes two packets, or possibly more, which may be derived geometrically from each other by a glide of 1.73 Å along (110) and 180° rotation. Weight loss above 190° C-3670 C exceeds that indicated by the Hofmann structure but conforms reasonably with loss indicated by a structure after that proposed by Edelman. Inverted Si-O tetrahedra are presumed to equal the number of univalent cations

It is suggested that the exchangeable cations form hydroxides during thermal analysis by reaction with (OH)− at the apex of inverted Si-0 tetrahedra. The resulting H2O and NH4OH are lost during thermal analysis, thus explaining excessive weight loss. Ca (OH)2 and Mg(OH)2 so produced release one mole of H2O during thermal analysis. KOH, NaOH, and LiOH are not decomposed below 1,000° C.

Thermal products vary with exchangeable cation and crystallinity increases with prior drying. The Li+ and Ca++ modifications produce beta-quartz and alpha-cristobalite with spinel and glass, whereas the other modifications produce only spinel and glass.
Variations in Viscosity of Clay-Water Suspensions of Georgia Kaolins
Authors: Woodward LeRoy A.
Published: August 2006

The viscosity of clay-water suspensions is an important factor in determining commercial uses of Georgia Kaolins. Impurities, such as montmorillonite type minerals, in these basically kaolinite clays play a part in causing variations in viscosity. However, seemingly pure kaolinite clays also show variations which seem to be related to morphology and degree of crystallinity. Studies are underway to determine the various factors involved.
Interstratified Layer Silicates in Some Soils of Northern Wisconsin
Authors: Whittig L. D. , Jackson M. L.
Published: August 2006

Examination of the silt and clay fractions of two northern Wisconsin soils, Omega loamy sand of the Brown Podzolic group and Ahmeek loam of the Brown Forest group, revealed considerable quantities of interstratified layer silicates. The two soils contained montmorin, vermiculite, chlorite, and illite both as discrete and interstratified components. Regularly alternating montmorin-illite structures, which registered a 28 Å first order diffraction peak, and vermiculite-illite structures, which yielded a 24 Å first order peak, were observed in the fine silt fractions of the Ahmeek loam A3 and B22 horizons, respectively. Weak diffraction peaks in general and lack of binary mixture average spacings was suggestive of ternary or quarternary interstratification of illite, chlorite, vermiculite, and montmorin in the medium and fine clay fractions of the Ahmeek loam horizons. Randomly interstratified vermiculite-chlorite and vermiculite-montmorin, as revealed by comparative basal diffraction peaks before and after heating potassium saturated samples, were evidenced in the fine silt and clay fractions of the Omega profile.

Mixed layer components in the Omega and Ahmeek soils originated from illite and chlorite in the? horizons with a progressive increase in proportions of first vermiculite and finally montmorin with proximity to the soil surface. The observed weathering transitions within the mixed layer structures illustrates the effects of accelerated leaching which has taken place in these coarse textured soil profiles, even though these soils are relatively young (late Pleistocene).
Relation of Porosity and Permeability to the Origin of Diaspore Clay
Authors: Allen Victor T.
Published: August 2006

The apparent porosity of flint, boehmite and diaspore clays bears no direct, consistent relation to the permeability of the same type of clay or to the alumina content of each type. The coefficient of permeability varies with the type and the structure of each flint clay. Diaspore clays have high permeability compared to flint clays, and the boehmite clays measured generally have a permeability intermediate between that of diaspore and that of flint clays. The apparent increase in permeability with increase in alumina content suggests that permeability has increased as silica was removed from flint clay to form boehmite and diaspore clays.

A vertical pipe of diaspore clay 1½ inches in diameter was collected by Fred Mertens of the Laclede Christy Company at the Shockley-Thompson diaspore pit at Belle, Missouri. The pipe contains 69.16 percent alumina compared with 55.30 percent alumina for the average of the walls a few inches from the pipe. Diaspore in the pipe has vertical banding indicating it was deposited along a vertical crack. The formation of cracks in brittle flint clay is an important process in increasing the permeability and providing openings along which ground water can migrate.

A restudy of boehmite and diaspore clays emphasizes not only a replacement of the colloform and oolitic structures of flint clays by diaspore and boehmite, a gradual alteration of flint clay to diaspore clay along fractures, and second-generation diaspore cutting early diaspore, but also the importance of secondary processes in the origin of diaspore and boehmite clays.
Quantitative Evaluation of the Kaolinite and Illite in Underclays
Authors: Schultz Leonard G.
Published: August 2006

Oriented slides of twelve different mixtures of kaolinitic and illitic underclays were studied with the X-ray spectrometer and the resulting curves were evaluated on the basis of the area of the 001 peaks. Although the areas from the unmixed components varied greatly, within any given mixture the two clays were quantitatively comparable on the basis of a 1/1 001 peak area ratio. The considerable peak area variations from slide to slide are the result of different degrees of preferred orientation and are not due to any appreciable differences in crystallinity. Mixed-layering of expandable material with the illitic component does not affect the quantitative comparisons significantly.
The Colloid Science of Important Clay Minerals
Authors: Hauser Ernst A.
Published: August 2006

A few days after Dr. RudoIf Wegscheider of the University of Vienna celebrated his sixtieth birthday in October, 1919, he began his next class with the following words:

“Today I intend to start discussing with you the physico- and colloidchemistry of the element silicon. It is not only the most abundant of an the nonmetallic solid elements which occur on this earth, but it is also, in combination with other elements, by far the most widely distributed one, with the exception of oxygen. Its only real competitor in this respect is the element carbon. Carbon differs from silicon above all by its property of combining with itself, thereby forming a great variety of compounds. With our increasing knowledge of the chemical composition of these carbon compounds the foundation for organic chemistry was laid. Science is never at a standstill, however. I refer here to physico-chemistry and to the even more recent addition to the specialized branches of chemistry, colloid chemistry.

“I probably will not live to witness the importance that the colloid chemistry of siliceous matter will play in the not too distant future. In my opinion the physico- and colloid-chemistry of matter containing silicon as its maj or component will become a serious competitor to organic chemistry.”
Forces and Adsorption at Solid Surfaces
Authors: McMillan W. G.
Published: August 2006

Essentially all interactions between atoms, molecules and ions spring from the electrical charges borne by the nuclei and electrons of which they are constituted. Two broad classes of interaction are distinguished by the terms “chemical” and “physical,” the former referring to those cases wherein some of the electrons of the two participants have become shared, with the consequent formation of a chemical bond. Such chemical forces have the property of saturation, are of very short range, and are usually associated with the comparatively large binding energies of a few electron volts. Some of the more important types of physical interactions, listed more or less in order of decreasing energy, are: ion-ion, ion-dipole, dipole-dipole, ion-induced dipole, induced dipole-induced dipole, etc. Those not involving ions are often grouped together under the term “van der Waals forces,” and generally have energies of only a fraction of an electron volt. The (long-range) ion-ion interactions (“ionic bonds”) are mainly responsible for the stability of ionic crystals, and thus may have energies comparable with those of chemical bonds.

An adsorbed molecule interacts very nearly additively with all the constituent atoms and ions of the adsorbent surface, and with other adsorbed molecules as well. The collective effect may be described through the “energy of adsorption,” which will generally be a function of the amount adsorbed. In physical adsorption, multilayer films and capillary condensation may occur at gas pressures approaching saturation.

The small size and high dipole moment of the water molecule make it strongly adsorbed on ionic substrates. The lamilar structure of the clay minerals furnishes enormous surface areas for adsorption. Investigation of these interactions at the molecular level provides a fundamental basis for a more complete understanding of clay-water systems.
Synthesis of Clay Minerals at Low Temperatures
Authors: Henin S.
Published: August 2006

Numerous attempts have shown that it seems to be impossible to crystallize co-precipitates of silica and hydroxides; we therefore attempted to prepare clay minerals starting from solutions of their constituents. By allowing these dilute solutions (tenths of milligrams per liter) to pass slowly into a flask containing distilled water, it has been possible to prepare substances similar to clay minerals. These have been identified by x-rays, chemical analysis, dehydration curves, and electron micrographs.

Using as cations Mg, Fe2+, Fe3+, and Ni, minerals of the montmorillonite type have been prepared for various pH values (generally greater than 7). Below this, value, depending on the cations; oxides, hydroxides, or amorphous materials are obtained.

Under certain conditions in the absence of silica the glass vessel was attacked, and anti-gorites of Mg and Ni were then obtained. Always when the supply of silica was small, and with the cation introduced in the form of a very dilute solution, the process gave rise to montmorillonite. In the presence of K, illites were sometimes formed.

The method seems to be of very general application. Only the purely aluminum minerals offer difficulties of preparation. The significance of these results is discussed.
The Structure and Morphology of a Kaolin Clay from Les Eyzies (France)
Authors: Brindley G. W. , Comer J. J.
Published: August 2006

It is shown by x-ray analysis and electron micrographs that the clay from Les Eyzies is composed of about equal amounts of platy material (kaolinite), and rolled or tubular material (halioysite). Detailed examination of the electron micrographs shows oriented tubes or rolled sheets which may have originated from well-aligned platy material which has fractured and subsequently curled into rolled forms. Hexagonal features on the surfaces of the rolled forms are described. The laboratory results are correlated with geological data on the formation of the clay.
Comparison of a Natural Bentonite with its Synthetic Analogue
Authors: Sand L. B. , Crowley M. S.
Published: August 2006

Comparison was made between a sample of Wyoming bentonite and its synthetic analogue. Equivalent decomposition temperatures and mineral phases were obtained in hydrothermal environments and by calcinations.
Contribution to the Study of Sepiolite: II. Some Considerations Regarding the Mineralogical Formula
Authors: Martin-Vivaldi J. L. , Cano-Ruiz J.
Published: August 2006

It is suggested that the minerals of the palygorskite-sepiolite group occupy the region of discontinuity between dioctahedral and trioctahedral minerals. There is thus a series of minerals, the two extremes having a planar lattice, and the intermediate members a fibrous lattice. The lamellar-fibrous change in structure takes place as the number of vacancies increases progressively.

Among the minerals of fibrous structure, the structural change from sepiolite to atta-pulgite occurs in such a way as to allow no more than one vacancy per structural fiber, and per half cell, as if this vacancy were not distributed at random, but symmetrically among the octahedral positions. The greater the number of vacant octahedral positions, the smaller the extension of the octahedral layer. The margin of variation in the number of vacant octahedral positions per structural fiber is greater in sepiolite than in attapulgite, probably because of the greater width of the fiber in the former mineral.
Contribution to the Study of Sepiolite: III. The Dehydration Process and the Types of Water Molecules
Authors: Martin-Vivaldi J. L. , Cano-Ruiz J.
Published: August 2006

A detailed study has been made of the dehydration of sepiolite. This work, together with other studies of dehydration in vacuo and over phosphoric anhydride, rehydration of samples heated to various temperatures, specific surface, water uptake, and x-ray examination of natural and heated samples (to be published later), lead us to certain conclusions regarding types of water in sepiolite. A comparison is made with attapulgite.
Forces Between Suspended Bentonite Particles
Authors: van Olphen H.
Published: August 2006

Purified sodium bentonite suspensions in water display rigidity at concentrations as low as about 2 percent. On addition of NaCl the yield stress decreases, but beyond about 5 meq/ liter of NaCl it increases. The same is true for the relative viscosities and the sediment volumes of more dilute suspensions. This is interpreted as a flocculation-deflocculation-floccu-lation sequence. The paradoxical phenomenon of flocculation of the clean suspensions is explained by the concept of positive edge charge of the clay plates, allowing positive edge to negative flat-surface flocculation.

Both the purified and the salt-flocculated gels show Bingham flow behavior. When Good-eve’s analysis of Bingham flow is applied, the linking force between the clay plates in the pure gels is computed at about 10−4 dyne.

The salt-flocculated gels show thixotropic hysteresis, whereas the pure gels set immediately after stirring. This means that there is no energy barrier for gelation in the pure gels, which is in line with the proposed mechanism of association due to Coulomb attraction. In the salt-flocculated gels there must be an energy barrier causing thixotropic hysteresis. This might be expected from the summation of residual double-layer repulsion and van der Waals attraction. Considering thixotropic stiffening as slow coagulation, the height of the energy barrier could be calculated from the thixotropic increase of the modulus of elasticity with time after previous shear breakdown of the structure. The reasonable value of 7 kT was found for the height of the energy barrier of a gel containing 30 meq/liter of NaCl.
Kinetic Studies on Montmorillonites and Nontronite by the Acid-Dissolution Technique
Authors: Osthaus Bernard
Published: August 2006

Several 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

Hydrogen 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

X-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

Glauconitic 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

The 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

Synthetic 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.