bluuebunny/crossref_metadata_2025 huggingface dataset:
Gravimetric Determination of Monolayer Glycerol Complexes of Clay Minerals
Authors: Kinter Earl B. , Diamond Sidney
Published: August 2006

Glycerol-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

The 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

Clay 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

The 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

Various 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

Further 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

Differential 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.
Clay Minerals of the Outcropping Basal Cretaceous Beds Between the Cape Fear River, North Carolina, and Lynches River, South Carolina
Authors: Heron S. Duncan
Published: August 2006

The basal Cretaceous beds of the area are subdivided into three units: the Cape Fear formation, Middendorf formation and Bladen member of the Black Creek formation. Stratigraphic position and lithology indicate that the Cape Fear is the oldest and the Middendorf is in part the landward facies of the Bladen. The Middendorf sediments are fluviatile and the Cape Fear and Bladen sediments are probably marine.

The Cape Fear and Bladen contain abundant montmorillonite, some kaolinite and lesser amounts of illite. In the Middendorf kaolinite predominates, although a few samples have small amounts of montmorillonite and illite.

Preliminary data indicate that in the Cretaceous-Tertiary sediments of the Atlantic Coastal Plain, montmorillonite occurs in abundance in the marine beds and kaolinite in the nonmarine sediments. The basal Cretaceous beds of the area studied fit into this scheme of clay mineral distribution.

The origin of the clay minerals of the Cretaceous formations studied is approached from sedimentary and empirical standpoints. The montmorillonite-marine and kaolinite-nonmarine associations strongly suggest that the montmorillonite has formed by marine diegenesis, whereas the sedimentary evidence suggests that the montmorillonite of the Cape Fear formation is detrital and the kaolinite of the Middendorf formation has formed by prolonged postdepositional weathering of a more varied clay mineral assemblage. The sediments of the Bladen unit in themselves offer little evidence as to the origin of their clay minerals. However, the predominance of kaolinite in the contemporary deltaic Bladen suggest that kaolinite was the only clay mineral supplied to the depositional area, and that in the marine part of the sedimentation area part of this kaolinite was changed to montmorillonite by marine diagnetic processes.
X-Ray and Infrared Data on Hectorite-Guanidines and Montmorillonite-Guanidines
Authors: Beck Carl W. , Brunton George
Published: August 2006

Clay-organic complexes of the clay minerals sodium hectorite and sodium montmorillonite with the hydrochlorides of guanidine, amino-guanidine, methylguanidine, and triamino-guanidine were examined for thermal stability by the oscillating-heating x-ray technique. Completely exchanged complexes increase the thermal stability of these two clays by as much as 275°C.

Infrared analyses were also made on these same clay-organic complexes. There is a marked difference between the infrared patterns of the clay—organic complexes and the patterns of the clays or the organic salts alone. More experimental work must be done before it will be possible to interpret completely the clay-organic infrared patterns.
Chemical Weathering of Layer Silicate Clays in Loess-Derived Tama Silt Loam of Southwestern Wisconsin
Authors: Glenn R. C. , Jackson M. L. , Hole F. D. , Lee G. B.
Published: August 2006

Chemical weathering of layer silicate clay minerals in the major horizons of the Tama silt loam Prairie soil profile was followed down to 10 ft, where the calcareous parent loess was encountered, and on down to a depth of 13 ft. The predominant constituents of the clay fraction (- 2 μ) at all depths in the soil profile were montmorillonite (42 percent) and illite (20 percent), although vermiculite (12 percent), kaolinite (5 percent) and amorphous material (15 percent) were also in fair abundance. Deposition of secondary inter-layer alumina was appreciable in the uppermost soil horizons but became less in amount in the deeper soil horizons. Quartz was not found in the clay fractions of less than 0.2 μ in diameter at any depth in the soil profile, although both quartz and feldspars occurred in the coarse clay.

Vermiculite decreased from about 18 percent in the coarse clay and 5 percent in the fine clay of the deeper calcareous horizons to small amounts toward the soil surface, disappearing altogether in the fine clay ( - 0.08 μ). Little variation was found in the montmorillonite percentage of the clay in the subsoil and lower horizons (64 to 75 percent of the fine clay), but a decrease in the 18Å diffraction intensity of montmorillonite concurrent with an increase in amorphous silica and alumina (15 to 27 percent of the fine clay) was observed in the upper, acid, soil horizons, suggesting that montmorillonite is not a stable weathering product in the latter. Elemental analyses of the fine clays showed about 1.1 out of 4 octahedral positions to be Fe, 2.5 to be Al, and 0.4 to be Mg. A slight decrease in Fe and increase in Al in the montmorillonite octahedral structure occurred progressively in approaching the more intensely weathered zones near the soil surface.

The results suggest that dioctahedral montmorillonite has formed to considerable extent in both the calcareous and noncalcareous horizons by chemical weathering of tri-octahedral ferromagnesian mica, through a vermiculite intermediate stage. The decrease in amount of the silt fractions of density greater than 2.66 g/cm3 (found to be composed mainly of biotite, chlorite, and amphiboles) in going from the calcareous horizons toward the soil surface approximately equalled the increase in montmorillonite percentage of the soil, suggesting that montmorillonite of the loess originated by chemical weathering of the ferromagnesian minerals of the silt. The genesis of the loessial montmorillonite begins long before the free CaCO3 has been leached out (6 percent montmorillonite in the loess at 13 ft) and continues to a maximum (14 percent) in the B horizon. Some eluviation of montmorillonite from the A horizon into the B horizon was evident.
A Study of the Synhesis of Hectorite
Authors: Granquist W. T. , Pollack S. S.
Published: August 2006

Hectorite, a trioctahedral magnesium montmorillonite, has been synthesized at atmospheric pressure and reflux temperature. The reaction mixture was the system SiO2/MgO/Li2O (or LiF)/Na2O in a large excess of water. The starting ratios were based on the following formula for the mineral <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:c="http://cambridge.org/core/content" xmlns:core="http://cambridge.org/core" xmlns:m="http://cambridge.org/core/metadata" xmlns:cup="http://contentservices.cambridge.org" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest">[(LixMg6−x)Si8O20(OH)4]x−.xNa+.${\left[ {\left( {L{i_x}M{g_6}_{ - x}} \right)S{i_8}{O_{20}}{{\left( {OH} \right)}_4}} \right]^{x - }}^.xN{a^ + }.$

Li+ has been found to accelerate the crystallization, and reasons for this effect are considered. Lowering of the pH of the reaction mixture by the use of alkali metal fluorides rather than hydroxides, resulting in an increase in the solubility of Mg(OH)2, also caused the crystallization of hectorite to proceed more rapidly. The products containing Li+ and F− proxying for Mg2+ and OH−, respectively, were found to be most like natural hectorite.

The time-dependent data obtained in this work were rationalized on the basis of a postulated appearance of hectorite embryos in the dilute aqueous solution of Mg2+, OH− and SiO2, followed by growth of this material to crystalline hectorite by transfer of components from solution to the solid phase.

Strese and Hofmann (1941) also conducted synthesis work in this area. A comparison of the products resulting from the two techniques showed the main difference to be the presence of 00l spacings in the current product. These earlier workers made a point of the lack of 00l reflections.
A Mixed-Layer Clay Mineral Associated with an Evaporite
Authors: Grim R. E. , Droste John B. , Bradley W. F.
Published: August 2006

Clay partings in the ore beds in a New Mexico evaporite section include a range of mixed-layer clay mineral sequences of the corrensite type. Specimens range from nearly regular alternations to sequences which depart from regularity to moderate degrees. The ore bodies consist of halite, polyhalite, sylvite, magnesite, dolomite, carnallite, and iron oxides.

Observed x-ray diffraction effects from representative specimens are compared with synthesized effects for montmorillonite- or vermiculite-chlorite layer sequences.

It is concluded that the segregation of the abundant Mg interlayer content into specific, regularly spaced interlayers represents the equilibrium relationship between a montmorillonite-chlorite or vermiculite-chlorite mixed assemblage and a mildly acid, Mg2+-, Na+- and K+-rich environment.
Hydraulic Flow Through Saturated Clays
Authors: Olsen Harold W.
Published: August 2006

The factors. (1) possible violations of Darcy’s law. (2) electrokinetic coupling. (3) high viscosity. (4) tortuous flow paths, an. (5) unequal pore sizes have been suggested as possible explanations for the differences between hydraulic flow rates in liquid-saturated clays and sands. The effects of these factors on hydraulic flow rates through saturated clays were investigated.

Hydraulic flow rates, electrical conductivities, and streaming potentials were measured on natural, sodium, and calcium samples of kaolinite, illite and Boston blue clay. Data were taken after increments of one-dimensional consolidation and rebound over the pressure range from one-sixteenth to 256 atm.

The influences of electrokinetic coupling on the hydraulic flow rates were calculated from irreversible thermodynamic relationships together with the hydraulic and electrical data. The other factors were studied by examining the extent to which each factor explains the discrepancies between measured flow rates and those predicted from Darcy’s law and the Kozeny-Carman equation.

The results show that. (1) the possible violations of Darcy’s law and electrokinetic coupling are insignificant. (2) high viscosity and/or tortuous flow paths fail completely to account for the discrepancies between measured and predicted flow rates in clays, an. (3) unequal pore sizes can explain all the discrepancies.
Shear Strength and Consolidation Characteristics of Calcium and Magnesium Illite
Authors: Olson Roy E. , Mitronovas Frederick
Published: August 2006

In recent soil mechanics literature attempts have been made to explain the engineering properties of clays in terms of surface chemical theories, particularly the Gouy—Chapman theory. Experimental confirmation of these theoretical predictions have been restricted almost exclusively to studies performed on fine grain size fractions of montmorillonite. It seemed desirable to determine experimentally the effect of physico-chemical variables on the engineering properties of a more typical engineering material. The < 2 μ fraction of Fithian illite was selected.

A study was made of the effect of variations in the pore water electrolyte concentration on the engineering properties of homoionic Ca- and Mg-illite. Pore water electrolyte concentrations ranged from 1 N down to about 10-4 N. Engineering tests included Atterberg limits, one-dimensional consolidation tests, and effective stress triaxial tests.

The electrolyte concentration was found to have only a small effect on the Atterberg limits, the maximum limits occurring at electrolyte concentrations between 0.01 N and 0.1 N. For virgin consolidation the soil seemed strongest at about the same range in electrolyte concentrations but the effect was not large. Electrolyte concentration had almost no effect on the position of the rebound (swelling) curves. The most important effect of electrolyte concentration seemed to be its effect on the geometric arrangement of the particles for samples that were sedimented from dilute suspension. The geometric arrangement of particles seems to be a more significant variable than the osmotic repulsion between particles.

There still appears to be merit in the old mechanical approach where the compression characteristics are explained by elastic bending (reversible), slippage (partially reversible), and rupture (irreversible) of particles. Double layer phenomena seem to exert a much smaller influence on the engineering properites of nonexpanding lattice clay minerals than is commonly inferred in the literature.
Influence of Adsorbed Water on Exchangeable Ion Movement
Authors: Low Philip F.
Published: August 2006

The concept of activation energy for ion movement is discussed. It is shown that the activation energy for exchangeable ion movement is directly correlated with the specific volume of the adsorbed water, with the resistance to freezing of this water and with the activation energy for deuterium oxide diffusion in this water. Electrical interaction between ion and clay appears to have little effect on the activation energy. Consequently, it is concluded that the most important factor governing exchangeable ion movement in the pores of a clay-water system is the structure of the adsorbed water.
Self-Diffusion of Exchangeable Cations in Bentonite
Authors: Lai T. M. , Mortland M. M.
Published: August 2006

A special integral form of the solution of Fick's law was applied to study the self-diffusion of Na, Cs, and Ca ions in Wyoming bentonite plugs by means of a radioactive tracer technique. A simple procedure for measuring diffusion coefficients was developed by depositing a thin radioactive tracer film on the surface of clay mineral plugs at controlled temperatures. Thin sections of the clay plugs were removed and radioactivity measurements made on the portion of the plugs remaining. The self-diffusion coefficients of the ions were evaluated by a graphical method from the solution of Fick's law at special boundary conditions. Under oven-dry conditions at 105°C diffusion of Na ion in a bentonite film was observed, while in the same experiment, SO42− ion did not diffuse. In a clay-water system, however, the anion diffused much more rapidly than the cation. Based on the experimental results of observing Na22- and S35-tagged Na2SO4 diffusion, different diffusion paths were proposed using a picture of the clay matrix as a structure with “channels.” Diffusion coefficients of exchangeable cations decreased with increasing clay contents. From the results of activation energy and self-diffusion coefficients of Na and Ca ions at various clay-water concentrations, the relative “hopping distances” of diffusing ions were calculated and discussed. It is suggested that in the self-diffusion of exchangeable Na ion in bentonite the ion could be hopping from one individual clay plate to another, and the Ca ion from one “package” of plates to another “package” of plates.
Hydrothermal Products Formed From Montmorillonite Clay Systems
Authors: McCaleb Stanley B.
Published: August 2006

An investigation of the behavior of clay systems in drilling fluids was begun in 1958 to determine the cause of gelation in lime-treated muds with increased temperatures incurred during drilling operations. Mud systems were evaluated by physical property measurements, cation exchange data, X-ray diffraction analysis, and electron microscopy before and after hydrothermal treatment. Selected samples were rerun after two years' storage at laboratory temperatures.

High-temperature gelation of lime-caustic muds is caused by the synthesis of calcium silicate hydrates, hereafter referred to as CSH, in general and tobermorite (XCaO, SiO2, H2O) specifically. These materials are considered the principal cementing agents of Portland cement. Spheroidal poorly crystallized tobermorite was produced from interlayered illite-montmorillonite muds. Laths and needles of crystalline tobermorite (11.3–11.6 Å type) were synthesized from the pure montmorillonite systems. Zeolite minerals were synthesized concurrently and were the dominant alteration product when Ca(OH)2 was not added to the system.

Synthesized aged (2 years) mud systems were studied after 8 weeks of dialysis with distilled water. Corundum was observed in samples where tobermorite formed, and was the dominant insoluble residue after HCl treatment. Much sharper diffraction maxima were obtained of the CSH compounds after dialysis or glycerine washing.

“Al-chlorite,” “Al-vermiculite,” and “Al-micas” were synthesized when treatments included aluminum ions. The products formed were of varying stabilities after washing with distilled water and HCl. Glycerol expanded the montmorillonite which had not reacted, but no expansion from the 10 Å or 14 Å d(001) spacing of the new product occurrred.
Halloysite and Gibbsite Formation in Hawaii
Authors: Bates Thomas F.
Published: August 2006

Desilication and removal of bases from the basalitic rocks of the Hawaiian Islands produces large amounts of halloysite and gibbsite, together with variable quantities of allophane and nontronite, iron and titanium oxides, and amorphous mineral and gel material.

The nature and relative abundance of intermediate and end products of weathering depend primarily upon the amount of rainfall, angle of slope, and texture of the rock. The formation of clay minerals is the common step in the transformation of primary silicates to oxides and hydroxides, but the amount and relative importance of the clay “stage” depend on the intensity of the weathering process.

Halloysite forms from plagioclase usually by alteration of first the core and subsequently the rim of the feldspar laths. No kaolinite was observed, its absence being attributed to the absence of fine-grained mica as an intermediate weathering product.

Gibbsite is produced by (1) removal of silica from halloysite, (2) dehydration of Al-gel, and (3) precipitation from solution. Although it is possible that the mineral may form directly from feldspar, halloysite is the common crystalline intermediate on both the megascopie and microscopic scales.

An amorphous transition state, probably ranging in composition from allophane to Al-gel, exists as part of the change from halloysite to gibbsite as evidenced by electron microscope and diffraction work on pseudomorphs after halloysite tubes found in certain samples studied in more detail than others.

Volcanic glass is the apparent source of most Al-Fe-Si gel material which upon dehydration becomes allophane, cliachite, or gibbsite depending on the kind and relative proportion of the cations present.
Clay Polymerization in Carbonate Rocks: A Silicification Reaction Defined
Authors: Bisque Ramon E.
Published: August 2006

A carbonate rock silicification reaction has been defined and shown to be dependent on the presence of clay in the host rock. Introduction of silica in soluble form(s) serves to polymerize the clay fraction, forming a continuous three-dimensional network. This siliceous network (polymer) can be separated from the rock by leaching away the carbonate minerals. Laboratory silicification of argillaceous carbonate rocks under controlled conditions has served to define critical variables.

Early studies were limited to argillaceous carbonate rocks from the Devonian Cedar Valley formation in eastern Iowa. Similar results have been obtained with carbonate rocks from the Devonian Chaffee formation in south-central Colorado. Some of the rocks in the latter formation have been silicified in nature, and yield siliceous polymers on acid leaching identical to those formed by silicification in the laboratory.

The reaction defined is suggested to be common in natural diagenesis of argillaceous rocks, clay-rich sedimentary material, and soils.

In the case of argillaceous carbonates this reaction affects physical properties of the rock which control processes involved in petroleum migration, ore-metal transfer, rock leaching and all diagenetic reactions that involve solution transfer.
Dehydration and Rehydration Studies of Clay Minerals by Infrared Absorption Spectra
Authors: Serratosa J. M.
Published: August 2006

The processes of dehydration and rehydration of montmorillonite and nontronite samples have been studied through infrared absorption spectra.

The changes observed in the intensity of the bands during dehydration show the analogy between absorption at 915 cm-1 (montmorillonite) and at 820 cm-1 (nontronite), their origin being a deformation vibration of OH groups.

During rehydration of the montmorillonite sample, the recovered OH groups occur in two different forms, in accordance with the results of differential thermal analysis.
Cation Exchange of Organic Compounds on Montmorillonite in Organic Media
Authors: McAtee James L.
Published: August 2006

Cation exchange of dimethyldioctadecylammonium (DMDO) ion for dimethylbenzyllauryl-ammonium (DMBL) ion previously reacted with centrifuged homoionic Na+ bentonite has been demonstrated. The amount of DMBL ion removed from the clay was determined by ultraviolet spectroscopy.

In order to shift the exchange equilibrium toward removal of the DMBL cation, a large excess of DMDO cation was required. At the limit of these experiments, it was found that 16 percent of the DMBL cation was exchanged.
Controlled Synthesis of Heteropolytypic (Mixed-Layer) Clay Minerals
Authors: Iiyama J. T. , Roy Rustum
Published: August 2006

The conditions for the formation of various heteropolytypic or mixed-layer phases were determined in a hydrothermal study of synthetic mixtures along the join talc—Na-saponite—Na-phlogopite composition. Heteropolytypes of talc and saponite from compositions between talc and a saponite solid solution and of saponite and a 10 Å sodium mica (Na-phlogopite?) from compositions lying between saponite solid solutions and Na-phlogopite have been prepared reproducibly.

At 1 kb in the temperature range 450-575° C, randomly stacked heteropolytypic phases were formed and persisted. At higher pressures the regular heteropolytypes (regularly interstratified or mixed-layer minerals), generally 1:1 phases, were formed. The genesis of heteropolytypes in nature is discussed on the basis of these results.
Relation of Diagenetic Alteration and Soil-Forming Processes to the Uranium Deposits of the Southeast Texas Coastal Plain
Authors: Weeks Alice D. , Eargle D. Hoye
Published: August 2006

The Upper Eocene Jackson Group is the chief host rock of the uranium deposits in the Karnes area of the southeast Texas Coastal Plain. It is highly tuffaceous and the uranium deposits are within approximately 100 ft of the unconformity with the overlying Catahoula Tuff (Miocene?). Glass shards, fragments of sanidine and plagioclase, grains of finegrained volcanic rocks, and biotite and other minerals in these sediments were highly reactive chemically, causing complex diagenetic alteration and the development of alkaline carbonate pore water. Extensive caliche development and silica induration associated with a recent hotter, drier climate favored the concentration of uranium. The origin of these shallow uranium deposits is believed to have been controlled by the complex diagenesis of the highly reactive volcanic detritus, by development of a “builtin” solvent for uranium (the alkaline carbonate pore water), and by climatic, structural, and permeability conditions that allowed concentration and deposition of uranium rather than dilution and dispersal. The tuffaceous rocks are considered to have been the source of the uranium and associated molybdenum, phosphorus, and arsenic.
Identification of Clay Minerals and the Study of Argillaceous Rocks By the Imbibo-Metric Method
Authors: Konta Jiří
Published: August 2006

The imbibition of liquid by argillaceous rocks containing predominating kaolinite, illite, “open” illite, and montmorillonite with the use of absorption apparatus is described. Results of the following studies are given: (1) imbibition by pulverized and freely poured samples; (2) imbibition by specimens pressed (30 atm) into the form of small cylinders having a base of 100 mm2; (3) the course of imbibition by artificial aggregates of kaolin from Sedlec, Bohemia, pressed under different pressures (20, 30, 40 atm); and (4) imbibition by natural, oriented, ground, flat sections of the same samples which were prepared in the form of rectangular prisms, with a base of 100 mm2.

The constant k in the sorption equation, which is dependent on the form of clay particles and the tortuosity of pores in argillaceous aggregates under particular working conditions, has been computed. This constant has been calculated for water (polar liquid) and tetraline (nonpolar liquid).

A new quantitative diagram for identification of clay minerals by the imbibometric method has been constructed. In it, not only the time of imbibition and the qualitative features expressing themselves on the ground, flat section—such as swelling and nature of contours (Konta, 1961)—are taken into consideration, but also the area occupied by a drop of water and a drop of ethylene glycol and the wettability ratio Pegl/aq.
Characterization of Montmorillonite Saturated with Short-Chain Amine Cations: 2. Interlayer Surface Coverage by the Amine Cations
Authors: Kinter Earl B. , Diamond Sidney
Published: August 2006

Portions of Wyoming bentonite were saturated with a series of short-chain aliphatic amine and quaternary ammonium cations, and the amine content remaining after washing was determined by combustion analysis. For those amine cations containing one or two carbon atoms, the amount of amine found was greatly in excess of the cation-exchange capacity. It is thought that this excess consists of amine cations or uncharged amine molecules which have become partly embedded in the holes associated with the oxygen rings of the silica sheet surfaces. For the larger tertiary amine cations, slightly less than the exchange capacity was found, presumably owing to blocking of some exchange sites by steric interference.

Upon treatment of the amine-saturated clays with glycerol and quantitative determination of the glycerol retained as a monolayer, it was found that these clays retain considerably less glycerol than the original bentonite. The glycerol retention values were employed to provide quantitative estimates of the interlayer clay surface left unoccupied between cation pillars. The percentage of original interlayer surface left unoccupied ranged from about 75 percent for methylamine to essentially zero for the larger tertiary amine cations.

The validity of the areas calculated from the glycerol retention results was indirectly confirmed by deriving estimates of the cross-sectional areas of the several cations from the observed reductions in amount of glycerol retained. These experimentally derived cross-sectional areas were found to be in satisfactory agreement with areas of the cations projected from atom models.
Differentiation between Endellite-Halloysite and Kaolinite by Treatment with Potassium Acetate and Ethylene Glycol
Authors: Miller W. D. , Keller W. D.
Published: August 2006

Halloysite and endellite yield 10 Å basal spacings after grinding with potassium acetate (using a modification of Wada’s procedure) and washing with water and ethylene glycol, whereas the basal spacing of kaolinite, similarly treated, remains at 7 Å. The technique applies satisfactorily to sedimentary and hydrothermal halloysites, various commercial kaolins, ball clays, flint and plastic fire clays, and artificially prepared mixtures of halloysite and kaolinite. Similar responses to the treatment by both laboratory-dehydrated endellite (thereby collapsed to 7 Å) and naturally occurring halloysite add support to the concept that endellite is a progenitor of halloysite.
Industrial Applications of Bentonite
Authors: Clem Arthur G. , Doehler Robert W.
Published: August 2006

Bentonite is employed by industry to perform a multitude of jobs. Certain industrial applications become apparent from an understanding of the composition and structure of bentonite, and the properties they create. These properties are utilized chiefly when the material is suspended in a liquid, usually water; or as a dried powder or granule.

Most industrial applications involve the swelling property of bentonite to form viscous water suspensions. Depending upon the relative proportions of clay and water, these mixtures are used as bonding, plasticizing, and suspending agents.

Bentonites disperse into colloidal particles and, accordingly, provide large surface areas per unit weight of clay. This large surface area is a major reason why bentonite functions so well in stabilizing emulsions, or as a medium to carry other chemicals.

Bentonites react chemically with many organic materials to form compounds which are used chiefly as gelling agents in a variety of organic liquids.

Bentonites are selected for each industrial need on the basis of type and quality. This selection is based principally on physical properties, and chemistry of the bentonite becomes involved only to the extent that it influences the physical properties.
Clay Minerals in the Ceramic Industries
Authors: Smoot Thomas W.
Published: August 2006

The physical, chemical and mineralogical characteristics of clays used in the ceramics industries are briefly outlined. Clays used include ball clays, fireclays, high-alumina clays of the diaspore and burley types, and three-layer types. The high temperature phases and bonding characteristics are briefly reviewed as are the uses of these various clays in the structural clay products, whitewares and refractories.

The importance of clays in the past for ceramics and, in particular, refractories is reviewed and evaluated for future importance.
Hydrothermal Kaolinization (Endellitization) of Volcanic Glassy Rock
Authors: Keller W. D.
Published: August 2006

A vitreous, perlitic rock near Etzatlân, west of Guadalajara, Mexico, has been argillized by hot spring activity. A continuous outcrop from fresh rock to relatively pure clay (halloysite) is exposed, and samples were collected along it to trace the progressive alteration. Alkali metals and silica were leached during argillation, as was shown by analyses of the solid samples and solutions from laboratory hydrolysis of the rock. The interpretation that the original clay mineral was endellite is supported by experiments treating the clay with K-acetate and ethylene glycol. The random arrangement of Si-O-Al in the glass is thought to have favored development of disordered stacking in the clay mineral formed, hence endellite, and random distribution of very fine-grained clay crystals in the mass of clay.
Gamma-Irradiation of Kaolinite
Authors: Corbett William J. , Burson John H. , Young R. A.
Published: August 2006

Studies have been made of the changes in physical and chemical properties of kaolinite produced by doses of 0.667 meV gamma-radiation ranging from 1018 to 1022 eV/g of ferrous ion dosimetry solution. Changes were observed in the degree of crystallinity, specific surface area, particle size, cation exchange capacity, and grinding properties. These changes are discussed in terms of the observed atomic displacements produced in the kaolinite structure by the radiation. Gamma-irradiation appears to provide a method for obtaining controlled variations in certain properties of kaolinite without the introduction of other complicating parameters.
Diagenesis in Clay Minerals—A Review
Authors: Keller W. D.
Published: August 2006

Diagenesis refers to the process, and the changes (usually excluding cation exchange) that take place in sediments after deposition, but definitions of the process vary widely over which changes, and what part (or all) of the time between the transportation of the sediment and the time that the sediment(ary rock) is studied, should be included in diagenesis. Furthermore, Weaver, Griffin, and others, have favored alternative explanations to account for many clay mineral distributions that previously have been interpreted as representing changes in clay minerals in both recent and ancient sediments, and which were referred to diagenesis.

Although agreeing that such alternative explanations account best for many distributions of clay minerals, additional evidence that presumably is convincing of diagenesis is presented herein to account for the formation of certain other occurrences of glauconitic mica, glauconite, illite, corrensite, kaolinite, and vanadiferous micaceous clay. A two-stage mechanism is proposed for a possible process by which illite and probably corrensite are formed: (1) cation sorption driven by energy (activities) of the ions in solution, and binding energy of the clay minerals, and (2) subsequent rearrangement of ions in the clay mineral to produce illite. It is finally proposed that diagenesis of clay minerals is characterized by the addition to and incorporation into them of Me ions, such as Mg, K, Ca, Na, Al, Fe, V, SiO2, and others, driven mainly by chemical energy and aided by mechanical and thermal energy, but as the latter two become more effective the process is designated metamorphism (anamorphism).

Long-time, diagenetic reactions after burial of sediments are probably less important, volume-wise, than provenance and terrestrial weathering in determining the mineralogy of argillaceous sedimentary rocks in the geologic column.
Topotactic Transformation of Muscovite under Mild Hydrothermal Conditions
Authors: Nicol Alastair W.
Published: August 2006

Studies have been made on muscovite single crystals treated under dry and hydro-thermal conditions at temperatures above 800°C. The course of reaction is markedly affected by the amount of water present in the system. In the presence of a large excess of water, appreciable reaction commences at 800°C with the formation of kalsilite and corundum. The kalsilite may bear an epitaxial relationship to the muscovite, but the corundum is quite unoriented. Reaction appears to proceed by solution of part of the muscovite and reprecipitation on unreacted areas. In the presence of low pressures of water the reaction course appears to be similar to that under dry conditions. Above 900°C a new phase has been identified which is similar to the spinel phase reported by Eberhart at temperatures above 1050°C. The phase is monoclinic and probably represents an intermediate stage between dehydrated muscovite and the spinel phase. A tentative mechanism is proposed for the dehydration of muscovite based on an inhomogeneous mechanism.
Thermal Transformations of Pyrophyllite and Talc as Revealed by X-Ray and Electron Diffraction Studies
Authors: Nakahira M. , Kato T.
Published: August 2006

Single crystal X-ray and electron diffraction studies were carried out to examine the thermal transformation sequences of pyrophyllite and talc, respectively. The results showed that both minerals transformed topotactically. No dehydroxylated talc phase was observed, while an anhydride of pyrophyllite was obtained at about 900°C. The presence of a distorted anhydride lattice of pyrophyllite tends to indicate a homogeneous mechanism for the dehydroxylation of pyrophyllite. In contrast, the diffraction features of heated talc together with the cell volume relationship between talc and enstatite suggest an inhomogeneous mechanism for this reaction.
Kinetics and Mechanisms of Dehydration and Recrystallization of Serpentine—II, Spectrum of Activation Energies for Recrystallization
Authors: Brindley G. W. , Hayami Ryozo
Published: August 2006

An order of magnitude calculation is made to determine the activation energies involved in the recrystallization of serpentine to forsterite. The so-called “activation energy spectrum” showing the proportion of material with different activation energies is estimated.
Geology and Mineralogy of the Sedimentary Kaolins of the Southeastern United States—A Review
Authors: Bates Thomas F.
Published: August 2006

Beginning with the work of Ladd in 1898, much has been written about the kaolins of the Southeast, with maximum coverage on the deposits of greatest economic value. Early studies were, of necessity, general in nature but also contain excellent detailed descriptions. In the past 15 years increased demands for kaolins to meet specific requirements have resulted in a large amount of detailed research, much of it unpublished. This paper attempts to review the available information placing emphasis upon the geologic and mineralogical data and the interpretation thereof with respect to the occurrence, detailed character and variability, and probable origin of the clay deposits.

The commercial deposits of kaolin clay discussed herein lie throughout the sands of the Upper Cretaceous Tuscaloosa formation and are localized in a narrow belt along the southeast edge of the “fall line” from Macon, Georgia, to Aiken, South Carolina. The kaolin lenses are irregular in shape, size and purity, ranging from a few feet to a mile in length, and up to 50 ft in thickness. Variability within the lenses is a function of (1) the concentration and localization of non-clay materials (quartz, mica, gibbsite, pyrite, lignite; Fe2O3, TiO2, MnO), (2) the montmorillonite content, (3) the particle size and X-ray crystallinity of the kaolinite, and (4) the texture of the clay aggregate. These mineralogical, chemical and textural variables are not homogeneously distributed but reveal and help to explain differences between samples, layers, pits and the important hard and soft clay types of the region.
Possibility of Volcanic Origin of the Cretaceous Sedimentary Kaolin of South Carolina and Georgia
Authors: Buie B. F.
Published: August 2006

The Cretaceous sedimentary kaolin deposits of South Carolina and Georgia occur in a portion of the geologic column which contains abundant evidence of volcanic activity in Texas, Arkansas, Mississippi, and Puerto Rico. It is proposed that volcanic ash from eruptive centers in the Mississippi Embayment and Gulf Coastal region settled on land and was washed into adjacent valleys, lake basins, and possibly lagoons, along with varying amounts of residuum from the erosion surface; alteration of the volcanic ash to montmorillonite, and then to kaolinite, progressed under the influence of subaerial erosion in Cretaceous and later time whenever physical and chemical conditions were favorable.

Several perplexing and previously inadequately explained features of the deposits are clarified if we accept this hypothesis. These features include: (1) The purity of the deposits, being over 95 per cent clay mineral in many deposits 20 ft or more in thickness; (2) General absence of fossils; (3) Lack of bedding; (4) Prevalence of a small but nearly uniform content of TiO2 as minute crystallites of anatase; (5) Presence of elongate bevel-edged particles, now clay, which have the form of glass shards.

Both the “soft” and the “hard” clay are believed to have developed from the same source. At all places where seen in the field the hard clay occurs immediately beneath a prominent unconformity; its different properties are attributed to changes produced by subaerial weathering. Repeated wetting and drying, which resulted in a smaller particle size, and leaching of silica, resulting in a slight bauxitization, are considered important mechanisms.