bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Gelation on the Properties of Water in Clay Systems
Authors: Leonard Ralph A. , Low Philip F.
Published: August 2006

Particle size distributions in samples of Belle Fourche, Wyoming, Aberdeen, Utah, and Cheto bentonite were obtained by a centrifugation technique. From these distributions and the clay density the number of particles per gram was calculated for the different samples. Then the clays were mixed in different proportions with water and the clay concentrations required for thixotropy were determined. It was found that a smooth curve was obtained when the clay concentration required for thixotropy was plotted against the number of particles per gram of clay. A smooth curve was also obtained when the clay concentration at the upper plastic limit was plotted against the number of particles per gram of clay.

In each suspension the water tension at the upper plastic limit was measured at several temperatures. From the resulting data, the relative partial molar free energy, entropy and heat content of the water were calculated. In all cases the values were negative, suggesting that the water in the suspension had more order than pure bulk water.

When the water tension was measured in different suspensions of Aberdeen and Cheto bentonite it was found that the tension remained zero until the clay concentration was sufficient to allow gelation of the suspension. Thereafter, the tension increased rapidly with clay concentration. Consequently, it was concluded that the sol-gel transformation was accompanied by a change in the energy status of the included water. This conclusion was supported by reference to other investigations in which changes in water properties were noted on gelation.
Clay-Mineral Alteration in the Upper Mississippi Valley Zinc-Lead District
Authors: Heyl A. V. , Hosterman J. W. , Brock M. R.
Published: August 2006

Clay-mineral alteration in a carbonaceous shale bed seems to be related to hydrothermal zinc-lead depositions in the Upper Mississippi Valley district in southwestern Wisconsin, northwestern Illinois, and northeastern Iowa. A 3-in. thick, dark-brown, carbonaceous shale at the base of the Quimbys Mill Member of the Platteville Formation can be traced accurately in the Thompson-Temperly mine near New Diggings, Wis., through the ore bodies into alteration aureoles around the ore bodies and out into areas barren of mineralization or apparent alteration.

X-ray diffraction studies indicate a progressive alteration of the clay-mineral and, in part, nonclay-mineral components of the shale from unaltered rock into ore-zone rock. Illite of md polymorph in unaltered rock is altered to 1 m and 2 m illite in the altered rock, and 2 m illite polymorph increases markedly within the ore bodies. Accompanying this alteration, calcite decreases and dolomite and microcline increase in amount toward the ore zone; quartz remains unchanged. The conclusion that the alteration was effected by low-temperature and low-pressure environment over a geologically long period of ore deposition is supported by fluid-inclusion studies of the associated ore minerals, which indicate a maximum temperature of 120°C to 130°C, and the known stability of synthesized 1 m and 2 m mica polymorphs at 200°C and 15,000 psi water pressure.
Chemical Weathering of Biotite-Plagioclase Gneiss
Authors: Grant Willard H.
Published: August 2006

The weathering of biotite-plagioclase gneiss was studied in a warm humid climate under good drainage conditions, in De Kalb County, Georgia. A series of samples ranging from completely weathered to fresh rock were studied. The degree of weathering was determined by bulk specific gravity and abrasion pH of samples in various stages of decomposition. Quantitative determination of clay minerals was done by DTA. Results show that the stable products of andesine weathering are kaolinite and endellite, and that biotite weathers to a mixture of amesite and kaolinite. There is no volume change in the gneiss as it weathers from fresh rock with a bulk specific gravity of 2.78 to a completely friable saprolite with a bulk specific gravity of 1.4. The weathering is accompanied by an increase in kaolin minerals from zero to about 35 per cent. The process involves the solution of plagioclase and biotite with approximately simultaneous crystallization of clay minerals and hydrated oxides of aluminum and iron.
Recent Researches on Clay Minerals in Belgium and the Netherlands
Authors: Fripiat J. J.
Published: August 2006

Subjects of contemporary research in Benelux are enumerated.
Weathering Relationships Between Gibbsite, Kaolinite, Chlorite, and Expansible Layer Silicates in Selected Soils from the Lower Mississippi Coastal Plain
Authors: Glenn R. C. , Nash V. E.
Published: August 2006

Clays from two Reddish-Brown Lateritic soils from the southern Mississippi Coastal Plain were fractionated and the mineral associations and weathering transformations were examined. The clays were found to be dominated by well-chloritized expansible layer silicates, gibbsite and kaolinite, with smaller amounts of quartz, mica and anatase. The abundance of gibbsite appeared to be related to the presence of expansible layer silicates and to soil pH variations. This mineral and kaolinite were found in appreciable amounts in even the finest clay fractions. Quartz and mica decreased to insignificant amounts with soil depth and decreasing particle size whereas gibbsite content of the clays rose suggesting an interrrelationship between these minerals.
Dielectrophoretic Behavior of Clay Minerals I. Dielectrophoretic Separation of Clay Mixtures
Authors: McEuen R. B.
Published: August 2006

This paper describes a method and apparatus for separating clay particles according to their ability to store electrical energy. Separation is accomplished by opposing an electrical dielectrophoretic force by a mechanical centrifugal force. The apparatus used to create these forces consists of an axially rotating, fluid-filled cylinder in which a non-uniform electric field is maintained by means of radially disposed electrode vanes.

The behavior in this separator of illite, prochlorite, montmorillonite, halloysite, and kaolinite is reported. Observed differences in the dielectrophoretic force acting on these clays indicate that they can be separated one from another by this method.

The basic equations which govern the motion of particles in this separator are discussed. From these equations and known electrical properties of clays it is concluded that the large dielectrophoretic force which acts on a clay particle must have its primary origin in an interaction between the non-uniform electric field and induced ionic space-charge which presumably is created in the particle’s interlayer regions and in the loosely associated external surface layer.
Clay Mineralogy of Paleozoic K-Bentonites of the Eastern United States (Part 1)
Authors: Lounsbury Richard W. , Melhorn Wilton N.
Published: August 2006

Samples of altered volcanic materials, interbedded with dominantly carbonate sediments, were collected from Ordovician, Silurian, and Devonian strata in Michigan, Illinois, Kentucky, Pennsylvania, Virginia, and Alabama. These altered volcanics, originally called metabentonite and more recently K-bentonite, occur in thin seams commonly only a few inches thick and are generally believed to be altered Paleozoic volcanic ash falls because they contain typical igneous minerals in the heavy suite and retain textures and structures characteristic of ash deposits.

Petrographic, differential thermal, and X-ray analyses were made of these samples to determine the clay mineralogy. Mixed-layer illite-montmorillonite occurs in the majority of samples. Illite is present in all samples and chlorite occurs in a few samples. This is in general accord with findings of previous studies. The mixed-layer clay is believed to have been deposited as montmorillonite in a marine environment and subsequently altered largely to illite through fixation of K in the interlayer position.

K-bentonites from Michigan and Illinois contain a constituent which has a 7.6 Å d-spacing. It is suggested that this material may be of regional significance because its occurrence was confined to the Upper Mississippi Valley K-bentonites in samples of this study.
Cation Exchange Between Mixtures of Clay Minerals and Between a Zeolite and a Clay Mineral
Authors: Denny Patrick J. , Roy Rustum
Published: August 2006

The electron microprobe has been used to analyse mixtures of fine-grained silicates such as clay minerals in order to determine directly how cations distribute themselves between mixtures of two fine-grained ion-exchanging materials in pure water and in dilute solutions.

Cation distributions have been determined for mixtures of:

(a)

a zeolite, faujasite, and the clay mineral in an Arizona bentonite

(b)

the clay mineral in an Arizona bentonite and hectorite; and

(c)

three synthetic beidellites of varying charge density.

Distributions have been found for varying ratios of Ca to K ions in the suspensions. The results for the faujasite-bentonite mixture show complex behavior and exhibit curves with maxima and minima. For the system bentonite-hectorite most of the Ca goes to the montmorillonite in the bentonite. For the mixture of synthetic beidellites, the results are rather confusing but it appears that the calcium is more associated with the beidellite with the highest exchange capacity. In all these systems, hydrolysis takes place and the hydronium ion plays a part in determining the equilibrium.
Lateral Clay Mineral Variations in Certain Pennsylvanian Underclays
Authors: Parham Walter E.
Published: August 2006

X-ray diffraction techniques were used to identify the clay mineral assemblages of Pennsylvanian underclay samples taken mainly from beneath the Colchester (No. 2) and Herrin (No. 6) Coals of Illinois and the Middle Kittanning Coal of Ohio. The clay minerals present are kaolinite, illite, chlorite, vermiculite, montmorillonite, and mixed-layer clay minerals. The minerals are not restricted to any particular stratigraphic unit, and their areal distribution is related to paleogeographic position in the original basin of deposition. Kaolinite shows a decrease in abundance from near shore to more basinward areas; illite is not present in near shore regions, becomes common basinward, and then shows a decrease with increasing distance from shore; chlorite is not found in near shore or in extreme basinward areas but is most common slightly basinward of the illite maximum; montmorillonite is fairly rare but is prominent in the most basinward positions; vermiculite is uncommon but usually occurs where kaolinite is the dominant mineral; mixed-layer clay minerals are present in all samples, constituting a small fraction of the clay minerals in the near shore regions but increases to the major constituent in the most basinward areas.

Clay minerals entering the basin of deposition during underclay formation were mainly kaolinite and mixed-layer clay minerals. As the mixed-layer clays were carried basinward into waters of increasing salinity, some of the mixed-layer clays, formed from weathered illite and chlorite, preferentially adsorbed potassium and magnesium and were regraded. Mixed-layer clay minerals that had undergone severe structural damage during weathering were not regraded and were deposited further basinward.

Maps showing lateral variation of clay minerals in an underclay also show the paleogeography. These maps may be used in outlining positive areas and deltas, or specific types of clay deposits.
Expansion of Fractionated Montmorillonites Under Various Relative Humidities
Authors: Messina Mario L.
Published: August 2006

Distinction between the non-expanding three-layer clay minerals, illites, and the expanding three-layer clay minerals montmorillonites is accomplished by glycolation treatment. Distinction among the montmorillonites can be accomplished if the interlayer cation, type and amount of adsorbed liquid, and particle size are kept constant. With these variables constant, the expansion of montmorillonites can be correlated with particle size and/or charge on the tetrahedral layer.

Sodium saturated montmorillonite samples taken from 0–100 per cent relative humidity generally exhibit three hydration levels. Coarse fractions and fractions that possess high charge densities per unit area, compared to fine fractions and fractions that possess low charge densities per unit area, expand the most at low humidities and expand the least at high humidities. This is explained by cation or surface hydration and the strength of the bond between the layers. Introduction of potassium into the interlayer positions of the montmorillonite lattice decreases the ability of the silicate layers to expand. Examination of the diffraction patterns reveals that physical combinations of particles with different hydrations, interlayer mixtures of hydrates, and interlayer mixtures within the physical combinations have been produced.
Structures of Brittle Micas
Authors: Takéuchi Y.
Published: August 2006

The crystal structures of xanthophyllite,
CaMg2Al(Al3Si)O10(OH)2(a
1M structure) and margarite
CaAl2(Al2Si2)O10(OH)2(a
2M1 structure), have been refined by
three-dimensional least squares. Ordering of Mg and Al has been observed in
the octahedral layers of xanthophyllite. There is no significant evidence
for ordering among cations in the silicate layers of margarite. The
tetrahedra are rotated about 23° in xanthophyllite and about 21° in
margarite. The configuration of the octahedral layers in margarite has the
same features as those in muscovite and dickite.

The mode of deformation of the silicate layer is roughly similar in both
structures, but there are important differences. These differences are
caused by the different configurations of the octahedral layers and are a
common feature among micas. In the aluminum octahedral layer, the oxygen
hexagons whose corners are apices of tetrahedra have short edges of 2.81Å
and a pair of longer edges of 3.35Å (distances are averages obtained from
the structures of margarite, muscovite and dickite). Because of these longer
edges, the tetrahedra in the dioctahedral micas are tilted in addition to
having rotations caused by the short edges. The
z-parameters of the basal oxygen atoms in the
tetrahedra thus show maximum deviations of 0.19 ± 0.03Å in margarite and
0.12 ± 0.03Å for muscovite. On the other hand, in trioctahedral micas, the
edges of the oxygen hexagons are almost the same length, with a maximum
deviation of 0. 05Å. The silicate layers in trioctahedral micas are
accordingly almost free from tilting of tetrahedra. The difference in
z-parameters in dioctahedral micas causes a
corrugation of layers and also causes a shift of interlayer
cations.

It is known that in trioctahedral micas, the direction of the OH bond is
perpendicular to (001), while in muscovite it is inclined to the
b-axis. Taking into account this asymmetrical
orientation of the OH bond, together with the above-mentioned interlayer
cation shifts, it is possible to show that a layer stacking by the operation
of the twofold axis in the space group of the 2M1
structure is no longer identical with that produced by rotations of ± 120°
about an axis perpendicular to (001). A more restricted number of operations
would therefore be possible in the generation of polytypes.

An index, D, has been defined that is a
direct measure of the misfit between octahedral and tetrahedral layers. It
will be shown that the layer silicates may be classified into three
categories with the aid of this index.
The Crystal Structure of Stilpnomelane Part I. The Subcell
Authors: Eggleton R. A. , Bailey S. W.
Published: August 2006

Ferric-iron stilpnomelane is triclinic, space group
Pl, a = 21.724 Å, b =
21.724 Å, c = 17.740 Å,
α = 124.14°, β =
95.86°, γ = 120,0°, Z = 16. The structure is dominated by a subcell for
which as =
1/4a, bs =
1/4b, cs =
1/4c, αs =
α,
βs =
β, γs = γ. The subcell
reflections have h-k =
3n, and have a trigonal intensity
distribution. The structure was determined from Patterson projections and by
trial and error. Three-dimensional refinement by least squares gave an it!
factor of 14.4 per cent for 296 reflections.

Stilpnomelane is a layer structure, having five anion and five cation
planes parallel to (001). An iron-rich octahedral sheet is flanked by two
tetrahedral sheets. The tetra-hedral sheets differ from those found in the
common layer silicates in that adjacent tetrahedra point in opposite
directions. Each tetrahedral sheet has 1.25 tetrahedra pointing toward the
octahedral sheet, and 0.75 tetrahedra pointing away. Detail in the
tetrahedral sheet cannot be determined from the subcell reflections
only.
The Torbernite Minerals as Model Compounds for the Hydrous Layer
Silicates
Authors: Ross Malcolm
Published: August 2006

A number of minerals and compounds of the torbernite
group are represented by the formula
A(UO2)(As,P)O4·3H2O
where A = K+,
NH4+ and/or
H3O+. Crystal-structure
analyses of
K(UO2AsO4)·3H2O,
NH4(UO2AsO4)·3H2O,
and
K0·45(H3O)0·55(UO2AsO4)·
3H2O recently completed by Ross and Evans (1964)
reveal the exact nature of their atomic arrangements. All three compounds
have interlayer structures formed by hydrogen bonding of water molecules
into infinite sheets composed of four- and eight-membered rings,
isostructural with the
[Si8O20]n8n−
layers of apophyllite. The interlayer K+,
NH4+, and
H3O+ ions, instead of entering
in between the
[UO2AsO4]nn−
layers co-ordinated by a hydration sphere of water molecules, are randomly
distributed over the water molecule sites. The formula of the interlayer
structure is written
[(H2O)3A]nn+.

A similar structural scheme may apply to the expanding layer silicates,
such as the montmonllonites and vermiculites. For these minerals,
particularly those with low to moderate cation-exchange capacity, the
potassium and ammonium analogs usually do not fully contract to the 10 Å
basal spacing on immersion in K+ or
NH4+ solutions, but rather
obtain a spacing of 11–14 Å. In these structures it is proposed that a
single or double layer of water molecules, arranged in a manner related to
one of the silica or ice polymorphs, enters between the 2: 1 layers, the
charge being balanced by random distribution of K+,
NH4+, and perhaps
H3O+ ions over the
H2O sites. The formula of the interlayer structure
is written
[(H2O)b-yAy]nny+
where A = K+,
NH4+, and/or
H3O+ and
ny+ is the charge
required to balance that on the 2: 1 layer. Other Group IA or Group IIA
cations may also be randomly distributed over water-molecule sites.
Structure of Pyrophyllite
Authors: Rayner J. H. , Brown G.
Published: August 2006

Pyrophyllite gives a diffraction pattern consisting
of sharp and diffuse reflections. The unit cell for all the reflections is
monoclinic with a = 5.17 Å,
b = 8.92 Å, c =
18.66 Å, β = 99.8°. From the absences, the space
group is either C2/c
or Cc but there are additional absences of
hkl reflections with
k ≠ 3n and
l even. The additional systematic absences
show that the structure is partially disordered, the disordered state being
based on a small subcell defined by the sharp reflections. This subcell is
monoclinic with a′ = a
= 5.17 Å, b′ = b/3 =
2.97 Å, c′ =c/2 = 9.33
Å, β′ = β = 99.8° and
belongs either to the space group Cm or
C2/m. Co-ordinates
have been found in the space group
C2/m by Fourier
and least-squares methods, which give R = 0.180
for h0l reflections
and R = 0.148 for hkl
reflections with h = 0, 1, 2. The Si—O tetrahedra
are twisted 10°–10.5° from the “idear” arrangement, leading to a ditrigonal
array of oxygens on the surfaces of the layers. The average Si—O bond length
is 1.610 Å and the average octahedral site—O distance is 2.025 Å. The
surfaces of the layers can come together in three ways; the O—O contacts for
any pair of layers are either approximately parallel to (010) with contacts
2.890 Å and 3.028 Å alternately or approximately parallel to planes making
angles of ±120° with (010) with contacts 3.009 Å, 3.066 Å, 3.009 Å, 3.343 Å
sequentially.
Observations on the Origin of Endellite in Kentucky, and Their Extension
to “Indianaite”
Authors: Keller W. D. , McGrain Preston , Reesman A. L. , Saum N. M.
Published: August 2006

Endellite is being formed south of Stanford,
Kentucky, in an acid environment (pH 3.0-3.7; acidity at source, p. 1).
Parent materials are principally a weathered residuum, derived presumably
from the Brassfield Limestone that lies between the illitic, Devonian New
Albany (Chattanooga) Shale and illitic, Ordovician Richmond Shale, and added
Si and Al dissolved from the New Albany Shale. The source of the acid is the
weathering iron sulfide in the New Albany Shale.

Apparent standard free energies of formation, calculated from aqueous
solution data measured from the shales, endellite, and residual clays,
indicate that essentially equilibrium conditions developed between the
endellite, the illite of the New Albany Shale, and the permeating solution.
Illites yield a range of values in
Ff,
owing presumably to variation in chemical composition and physical disorder
in the crystals, which also may be polymorphic; hence, illites likewise vary
in susceptibility to alteration and/or conversion of kaolin
minerals.

It is suggested that Indiana endellite (“indianaite”) was formed at the
Mississippian-Pennsylvanian unconformity in an environment similar to that
(Ordovician-Devonian) yielding the Stanford, Kentucky, endellite.
X-Ray Diffraction Automation and Its Use in Clay Mineralogy
Authors: McCaleb Stanley B.
Published: August 2006

The standard Philips X-ray Diffraction equipment has
been fully automated for continuous unmonitored operation. Modifications of
the equipment include a sample-changing device, goniometer-driven divergence
slits, pulse motor drive with eight-speed option, selective scan speed as a
function of hkl intensity, range change device,
and electronic programming of the complete operation. In addition,
simultaneous readout on the Brown Recorder strip chart and magnetic tape
provide records for visual and computer processing.

Computer programs have been developed for the processing of the digital
output that is in the form of cumulative pulse counts for the angular
position and the intensity of the reflection. These data are converted to
hkl spacings in angstroms and intensities
after removal of the background count. An identification program has been
developed that identifies the minerals and prints out the spacings and
intensities used for the identification. Solvation and heat treatment data
are utilized to aid in the identification of the clay minerals.

Selected data from sediments are used to illustrate the output of the
automated instrument and the increased resolution and speed of the
equipment.
Ordovician K-Bentonites of Iowa
Authors: Mossler John H. , Hayes John B.
Published: August 2006

Thin beds of altered volcanic ash, called
K-bentonite, are distributed widely in Ordovician strata of the eastern
United States. This study reports the mineralogy and stratigraphy of eight
such beds found in limestones and shales of the Decorah and Galena
formations (Middle Ordovician) of northeast Iowa and adjacent parts of
Minnesota, Wisconsin and Illinois.

The clay-size material of the Iowa bentonites consists almost entirely
of randomly interstratified illite-montmorillonite, with a range of illite:
montmorillonite ratios from 4:1 to 7:3. Thus, they are similar to Ordovician
K-bentonites reported by others from eastern states. The mica polytype is
dioctahedral 1Md to 1M of low temperature origin. In
contrast, the predominant clay mineral in the normal marine limestones and
shales is well-crystallized, 2M1, dioctahedral illite.
The contacts between bentonites and limestones or shales are distinct; in a
few exposures a thin zone of finely laminated, reworked bentonite is
observed directly above the bentonite. The bentonites themselves are
unlaminated.

Accessory sand-size mineral grains from bentonites consist of euhedral
apatite, euhedral zircon, sanidine, pyrite, biotite and hornblende, whereas
those from shales are organic apatite, quartz and calcite. The bentonite
assemblage is suggestive of volcanic origin, and is similar to Ordovician
K-bentonites east of Iowa.

Differential thermal analysis reveals that the clay mineral of
bentonites altered at low temperatures through a montmorillonite stage and
became more micalike by K fixation. In contrast, DTA indicates that the
illite of shales originated as mica and is slightly weathered toward a
montmorillonitelike phase. Laboratory saturation of clays from adjacent
bentonites and shales with K+ demonstrates similar
relationships.

The usefulness of bentonites as key horizons for correlation within the
Ordovician is limited by several difficulties. Removal of ash by
contemporaneous reworking, the probable multiple centers of volcanic
activity in the Appalachian region and the great number of essentially
identical bentonites within a stratigraphic interval are major problems.
A Disordered Kaolinite from Concepcion de Buenos Aires, Jalisco,
Mexico
Authors: de Pablo Liberto
Published: August 2006

A random-layer disordered kaolinite from Conception
de Buenos Aires, Jalisco, Mexico, gives an X-ray diffraction pattern
resembling that of halloysite but has a kaolinite morphology. The mineral
was located in a lignite deposit and, apparently was formed by alteration of
volcanic rocks from the Cenozoic, with rapid cooling and sedimentation in
lacustrine deposits. It is associated with plagioclase, quartz,
cristobalite, montmorillonite, goethite and organic material. The analysis
of purified material (44.84 per cent SiO2, 40.36 per
cent Al2O3, 0.30 per cent
Fe2O3, 0.31 per cent CaO, and
13.99 per cent ignition loss) corresponds to the formula
(Si3·88 Al0·11
Fe0·01) (Al3·99
Fe0·01)O10
(OH)8. X-ray diffraction indicated a
d001 of 7.56 Å, an
intense 020, and displaced and nonsymmetrical reflections corresponding to a
bi- and tridimensional diffracting system closer to halloysite than to
kaolinite. Computed cell edges were a = 5.18 Å,
b = 8.97 Å, and c
= 7.45 Å. Electron micrographs showed anhedral rounded particles averaging
0.22 µ in size, while infrared absorption indicated some displacement in the
absorption bands. The relationships of the mineral to kaolinite, halloysite
and disordered kaolinites are discussed in terms of the 7°38′ twist of the
tetrahedra, the intensities of the reflections, and the calculated
AlIV substitution.
Swelling Properties of Synthetic Smectites in Relation to Lattice
Substitutions
Authors: Harward M. E. , Brindley G. W.
Published: August 2006

Synthetic clays were prepared hydrothermally at 300°
to 350°C and 15,000 psi from gels with compositions calculated to give a
series of octahedrally and tetrahedrally substituted, 2:1-type layer
silicates with charges of 0.5N, 1N, 1.5N, 2N, 2.5N, and 3N, where N equals
the “normal” layer charge of montmorillonite. Besides montmorillonites and
beidellites, the products also contained other components, kaolinite,
saponite, paragonite and possibly amorphous materials, depending on the
initial gel compositions. Cation exchange capacities of
<2µ fractions treated for removal of
amorphous constituents were within the narrow range of 0.95–1.35 meq per g
rather than 0.45–2.70 meq per g as calculated from initial gel
compositions.

Comparisons between the expanding properties of these materials showed
that the beidellites expanded less readily than the montmorillonites upon
solvation with glycerol vapor and tended to give single interlayer
complexes. These differences were most pronounced when Mg was the saturating
ion, although they were also apparent with Ca.

The K-saturated montmorillonites gave greater expansion than the
beidellites on hydration at 100 per cent r. h. The montmorillonites also
exhibited greater rehydration than the beidellites after heating at
400°–500°C.

Beidellite exhibits properties of expansion that are intermediate
between those of montmorillonite and vermiculite. The results of this
investigation are consistent with the existence of somewhat stronger ionic
attractions in the beidellites than in the montmorillonites. The source of
the charge thus has an effect upon the properties of expansion.
Structural Charge Density as Indicated by Montmorillonite
Hydration
Authors: Jonas Edward C. , Roberson Herman E.
Published: August 2006

A sodium-saturated Texas bentonite was fractionated
into six particle-size ranges. The expansion of each fraction was observed
by X-ray diffraction under controlled humidity conditions ranging from 0–100
per cent r.h. At all humidities, the fine fractions expanded more than the
coarse. A single size fraction expands through a series 10 Å, 12.4 Å and
15.5 Å. The expansion from 10–12.4 Å occurs at progressively lower relative
humidities for smaller size fractions in the same way as the expansion from
12.4–15.5 Å. The gradation from high resistance to expansion in the coarse
fractions to low resistance to expansion in the fine fractions appears to be
continuous.

Interlayer cation density, which controls the resistance to expansion,
is dependent upon the structural charge density on the silicate layer. The
continuous variation of resistance to expansion that is a function of
particle size is interpreted to indicate a corresponding continuous
variation in structural charge with particle size.
Lithium and Potassium Absorption, Differential Thermal, and Infrared
Properties of Some Montmorillonites
Authors: Schultz Leonard G.
Published: August 2006

Investigations are underway concerning
inter-relations of X-ray analyses of chemically treated samples, infrared
absorption and DTA for a group of 28 montmorillonite samples. Results to
date generally support Greene-Kelly’s LiCl test for evaluation of the
proportion of tetrahedral and octahedral layer charge in montmorillonite.
Decrease in expandable characteristics of the montmorillonites owing to
K+-saturation is much more closely related to the
total layer charge than to charge distribution in tetrahedral or octahedral
layers.

As the tetrahedral charge increases and the octahedral charge decreases,
the infrared absorption band at 11.95µ is replaced by one at 11.35–11.5µ,
and the absorption band at 9.2µ decreases or disappears.

Most DTA dehydroxylation peak temperatures are related to charge
distribution as follows:
Organoclays Bonded to Polyethylene by Ionizing Radiation
Authors: Nahin Paul G.
Published: August 2006

Exploratory experiments on irradiation of mixtures of
polyethylene and organo-montmorillonites with gamma rays indicated that the
polyethylene became crosslinked to the organoclays. Subsequently, 264
samples of 1:1 clay-polyethylene compositions were irradiated with 2 MeV
electrons and tested for tensile strength and weight fraction extractable in
toluene at 110°C. From statistical analysis of the variables of clay
lattice, clay surface, polyethylene type and radiation dose it is concluded
that: (1) polyethylene can be bonded directly to the clay surface by
ionizing radiation, and (2) at least one organoclay bearing a
“polyethylenelike” chain, polyvinyl alcohol, is more effective than wholly
inorganic clay for the purpose of radiatively linking polyethylene to clay
surface. The data below show the markedly increased solvent resistance of
polyethylene radiatively bonded to clay over that of equivalently irradiated
pure polyethylene.
Thermal Stability of Bentonites in Foundry Molding Sand
Authors: Vingas George J. , Zrimsek Arthur H.
Published: August 2006

The effects of heat on the behavior of sodium and
calcium bentonite in bonding foundry sands were studied.

Tests such as differential thermal analysis, viscosity, and melting or
vitrification temperatures do not indicate the suitability of a bentonite
for foundry use.

The deterioration temperatures of sodium and calcium bentonite are 1180°
and 600°F respectively.

Reactivities of bentonites with cereal as affected by temperature and
mulling were also studied. Flowability of sands, defined as mold
densification in this paper, is better with heated calcium than sodium
bentonite.

Heating bentonites alone does not simulate the conditions encountered in
heating bentonite-sand mixtures in a mold.
Particle Arrangements and Differential Imbibitional Swelling in Deformed
or Deposited Kaolinite-Illite Clay
Authors: Tressler Richard E. , Williamson William O.
Published: August 2006

A fine-grained kaolinite-illite clay, in which planar
particle orientation resulted from filtration or plastic deformation,
swelled differentially when liquid water was imbibed by test pieces already
in the plastic state. Swelling was greater perpendicular than parallel to
the plane in which the clay platelets tended to be arranged. Filtration, in
contrast to deformation, gave test pieces that swelled more rapidly and
extensively. The slipbands, present only in plastically deformed test
pieces, restricted the swelling. They were arranged diagonally to the plane
in which the clay platelets tended to lie. The plastically deformed test
pieces showed enhanced expansion perpendicular to this plane when they were
made successively thinner by compression under a cylindrical roller. This
was attributed to improved planar orientation of the clay
platelets.
New Amine Reagents for X-Ray Determination of Expandable Clays in Dry
Samples
Authors: Rex R. W. , Bauer W. R.
Published: August 2006

Quantitative X-ray diffraction analysis of minerals
can most readily be performed on dry powdered samples. Current methods for
determination of expandable clays require either wet oriented samples
treated with glycerine or glycol or dry, randomly oriented samples treated
with amines. Trimethylamine has been used to expand the montmorillonite
structure to a 13.3 Å basal spacing. Unfortunately, this spacing is subject
to considerable peak interferences.

We therefore undertook a review of amine-montmorillonite complexes for
more suitable reagents. The formate and acetate salts of tri-n-hexylamine
and of dimethyl-benzylamine meet our requirements. The peak positions are
the same as for glycerine complexes, while the physical properties are the
same as for trimethylamine.

Detailed studies of tri-n-hexylammoniura ion absorption suggest single
layers of ammonium ions lying parallel to the crystal basal plane, double
layers in similar orientation, and a single layer with molecules on end. The
most useful orientation is the latter, which occurs in the presence of an
excess of the ammonium salt and gives a montmorillonite spacing 18 Å in dry
powdered samples.

Linear calibration curves with a standard deviation of about 5 per cent
of the amount measured can be prepared using the conventional internal
standard techniques. Minimum detectable amount of montmorillonite with
rate-meter techniques is 0.4 per cent and 0.2 per cent with scalar
techniques.

Several thousand analyses using tri-n-hexylammonium ion have
demonstrated its effectiveness for expanding a wide variety of
sediments.
The Status of Clay Mineral Structures
Authors: Bailey S. W.
Published: August 2006

The basic outlines of most of the hydrous layer silicate structures were determined during the 1930’s. Present escalating interest in obtaining additional detail is indicated by (a) publication of over twenty structural refinements (2-D or 3-D) during 1954-64, (b) publication of at least nine structures in 1965 or early 1966, and (c) personal communication that at least fifteen additional refinements are in progress. Points of especial interest in these recent studies follow.

1.

Octahedral cation order is common, but tetrahedral cation order is confirmed in only three cases. Because ordering of Si, Al does not significantly affect the statistical tests for centrosymmetry, centrosymmetric space groups that do not permit order should be avoided during refinement.

2.

Oversize tetrahedral sheets articulate with smaller octahedral sheets by tetrahedral rotation and, for dioctahedral species, by tetrahedral tilting around vacant octahedra. The latter mechanism influences the type and regularity of layer sequences. Undersize tetrahedral sheets articulate with larger octahedral sheets by tilting plus octahedral contraction or by inversion of some tetrahedra.

3.

The amount and direction of tetrahedral rotation and tilt, length of T—O, M—O, and O—O bonds, sheet thicknesses, and relation of cell dimensions to composition can now be predicted with some confidence.

4.

Variation in layer stacking (polytypism) is common. In some cases the stabilities of different polytypes can be explained by the relative amounts of repulsion and attraction between the ions in the structures. The stabilities can be correlated with the energy available in the environment of crystallization.
Layer Charge Relations in Clay Minerals of Micaceous Soils and Sediments
Authors: Raman K. V. , Jackson M. L.
Published: August 2006

Micaceous clays (“illites”) of a number of sediments, subjected to quantitative mineralogical analysis, ranged in different samples from 58 to 65% of a dioctahedral mica of muscovite type, from 3 to 8% vermiculite, from 0 to 10% montmorillonite, from 2 to 12% quartz, from 0 to 4% feldspars, from 1 to 2% rutile and anatase, from 0.3 to 1.2% free iron oxides, and from 16 to 30% chlorite. The soil clays contained less mica (13 to 35%) but more vermiculite (13 to 16%), montmorillonite (6 to 14%) and chlorite (30 to 33%), besides kaolinite (3 to 8%) and amorphous material (6 to 15%). The presence of the various minerals was verified by X-ray diffraction. When the interlayer K of these micaceous clays was replaced by hydrated Na ions through treatment with 0.2 n sodium tetraphenylboron in 1 n NaCl, the analytically determined vermiculite and montmorillonite contents increased. The freshly produced vermiculites had an interlayer charge of 177 to 198 me/100 g. During this replacement of interlayer K in a 1 N salt solution, the pH of the equilibrium matrix solution was observed to increase instead of decreasing as would be expected if oxonium (OH3+) ions were associated with K in the interlayer space, thus precluding the possibility of interlayer ONz+. The calculated stoichiometric equivalent of the pH rise established a significant uptake of protons by the lattice as K was released.

Thermal analyses of vermiculites show 0.5 to 0.7% higher OH water content than the parent micas. Oxidation of ferrous iron in the silicate structure, suggested as a possible mechanism for lowering of layer charge during weathering of mica to vermiculite, accounted for about 66% of this in samples high in iron (16.0% FeO) and only 30% of this in samples fairly low in iron. The rate of extraction of K from muscovite with no ferrous iron was found to be pH dependent, increasing at lower pH values. The data indicate proton incorporation with structural oxygens of the silicate sheet to form OH as a charge reduction mechanism in weathering of mica, independent of and additional to that involving the oxidation of ferrous iron.
Susceptibility of Interlayer Potassium in Micas to Exchange with Sodium
Authors: Scott A. D. , Smith S. J.
Published: August 2006

Interlayer K in muscovite, biotite, phlogopite, illite and vermiculite-hydrobiotite samples was replaced by cation exchange with Na. The rate and amount of exchange varied with the mineral and the level of K in solution.

Essentially, all the K in muscovite, biotite, phlogopite and vermiculite was exchangeable when the mass-action effect of the replaced KT was reduced by maintaining a very low level of K in solution. The time required for this exchange varied from < 10 hr with vermiculite to > 45 weeks with muscovite. Only 66% of the K in the illite was exchangeable under these conditions. When the replaced K was allowed to accumulate in the solution, the amount of exchange was determined by the level of K in solution required for equilibrium. These levels decreased with the degree of K-depletion and with the selectivity of the mica for K. The order of selectivity was muscovite > illite > biotite > phlogopite > vermiculite. Decreasing the K in solution from 10 to 7 ppm increased the exchangeable K in biotite from 30 to 100%. A K level of only 0.1 ppm restricted the exchange of K in muscovite to 17%.

A decrease in layer charge was not required for K exchange, but a decrease did occur in K-depleted biotite and vermiculite. Muscovite with the highest layer charge (247 meq/100 g), least expansion with Na (12.3Å), and least sensitivity to solution pH had the highest selectivity for K and the slowest rate of exchange. The K in vermiculite was the most readily exchangeable.
Mechanical Force Fields in a Clay Mineral Particle System
Authors: Geuze E. C. W. A. , Rebull Peter M.
Published: August 2006

Electrical double layer theory is used to analyze an idealized model unit of a clay particle system with the purpose of describing the mechanical stability in terms of an equilibrium of attractive and repulsive forces. Restricting the analysis to two dimensions, a symmetrical parallelogram formed by four typical clay mineral particles is taken as a representative unit of a flocculated clay and the interactions of mineral faces and associated electrolyte is investigated. The distortion energy of the system thus found is then directly related to the mechanical stability of the model unit’s structure as it varies from parallel to perpendicular orientation. The general pattern of behaviour of the model unit will be shown to be compatible with the mechanical behavior of the clay mass.
Equilibrium Theory of the Kaolinite-Water System at Low Moisture Contents, with Some Remarks Concerning Adsorption Hysteresis
Authors: Sposito Garrison , Babcock K. L.
Published: August 2006

A microscopic theory of the kaolinite-water system is presented, based upon the assumption that the clay-water interaction may be envisioned as partly hydration of the exchangeable cations and partly adsorption by the oxygen and hydroxyl surfaces. The theory treats exchangeable cation hydration quantum-mechanically as an ion-dipole phenomenon and considers water adsorption by the mineral surface as a problem in hydrogen bonding. A statistical mechanical model incorporating the quantum-theoretical results is then invoked to find the contribution of each component interaction to the initial portion of the adsorption isotherm for homoionic kaolinite. Good agreement between the theoretical calculations and available experimental data is achieved for water vapor adsorption by Li-, Na-, K-, and Mg-kaolinite, without the use of ad hoc empirical parameters. The concordance, in turn, is used to suggest that the basis for adsorption hysteresis in kaolinite-water vapor systems is the irreversible transition: mineral surface water → cation hydration water.
Kinetics of Decomposition of Cobalt Coordination Complexes on Montmorillonite Surfaces
Authors: Fripiat J. J. , Helsen J.
Published: August 2006

Montmorillonite may adsorb cobalt(III)hexammine and cobalt(III)chloropentammine cations, and the C.E.C. determined for these complex cations is of the order of magnitude of that obtained with ammonium. The infrared spectra of these coordination complexes adsorbed by the clay are similar to those observed for the corresponding chloride salts. However, when montmorillonite treated with these coordination complexes is dehydrated in vacuum or under moderate temperature conditions (<100°C) in a dry atmosphere, the infrared spectra are deeply modified. The complex cations decompose with NH3 evolution and ammonium formation. Cobalt(II)hydroxide is produced and ammonium cations balance the lattice electrical charge. The true decomposition rate was followed by IR absorbance of NH4 which showed that the complex decomposition followed that for the nomothetic decomposition of solid particles. The apparent activation energy of the decomposition was 20.5 and 43 kcal/mole for the CoCl(NH3)52+- and Co(NH3)68+-montmorillonite complexes respectively. An analysis of the combined chemical and IR data on the hexammine complex permitted calculation of the NH3 diffusion rate between collapsed montmorillonite sheets. When the interplanar gap approaches 1Å the diffusion coefficient is approximately 7 × 10-19 cm2/sec. In contradiction to their stability in solutions, the cobalt(III)hexammine cation is less stable than the cobalt(III)chloropentammine cation when absorbed on montmorillonite.
Infrared Study of the Thermal Decomposition of Ammonium Rectorite
Authors: Russell J. D. , White J. L.
Published: August 2006

Changes in the infrared absorption spectrum of ammonium-saturated rectorite on heating suggest that the ammonium cations are hydrogen bonded to water molecules when the mineral is hydrated. Further spectral changes above 300°C indicate that lattice OH groups are perturbed by protons liberated from the decomposition of ammonium ions giving rise to an absorption doublet at 3500 and 3476 cm-1. The doublet attains maximal intensity when decomposition of ammonium cations and dehydroxylation of the mineral is complete at about 550°C.

The perturbation effect occurs only for swelling dioctahedral minerals which derive their layer charge from Al-for-Si substitution.
Alteration and Formation of Clay Minerals During Cat Clay Development
Authors: Lynn Warren C. , Whittig Lynn D.
Published: August 2006

The natural tidelands sediments along the north shore of San Pablo Bay, California, are neutral in reaction and subjected to a wet, reducing environment conducive to ferrous sulfide accumulation. When the sediments are diked and drained, the environment rapidly becomes oxidizing and generally dry. Oxidation of the ferrous sulfide results in extremely acid cat clays within a year or two.

Undrained sediments from the area contain montmorillonite, chlorite, mica, and kaolinite that all give sharp X-ray diffraction patterns. Sediments drained for 6 years, although strongly acid, have virtually the same clay mineralogy as the undrained sediments. However, sediments drained for 60 years show a general deterioration of crystalline clay minerals, particularly chlorite. The deterioration decreases with depth until the deeper zones closely resemble the undrained sediments.

In separate laboratory experiments, chlorites were formed in an oxidized soil that was subjected to reducing conditions simulating the environment of the undrained tidelands sediments. The possibility exists, therefore, that chlorites in the undrained sediments may have formed subsequent to deposition.
Genesis of Refractory Clay Near Guanajuato, Mexico
Authors: Hanson Robert F. , Keller W. D.
Published: August 2006

Refractory clay, derived from hornblende chlorite schist that was hydrothermally altered along nearly vertical fractures and faults, occurs near Guanajuato, Mexico, a few kilometers south and east of the famous monument, El Cristo Rey. Part of the chlorite is expanding, i.e. probably mixed-layer vermiculitic chlorite or biotite. The most refractory clay is comprised chiefly of kaolinite, with variable amounts of finely crystalline quartz. Huge, thick “gossans” of silica have been deposited as surface-covers over the fractures; such silica gossans are fairly common over Mexican hydrothermal clay deposits and may be used as probable field guides to argillation.

The trend of mineralogical and chemical changes (analyses tabulated in the paper) during argillation of the Guanajuato material is traced in overlapping sequence, as follows:

(a)

bleaching of green ferro-ferric silicates accompanied by oxidation of part of the iron to “limonite”.

(b)

leaching of alkali and alkaline earths accompanied by

(c)

partial desilication of parent silicate minerals yielding kaolinite whose flakes are commonly oriented parallel with the chlorite of the schist, mobile silica, and finely divided quartz intermixed with the kaolinite

(d)

refinement (“purification”) of the clay by further kaolinization and removal of silica minerals and some iron oxide.

The final clay may run higher in silica than does its parent rock.