bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Gelation on the Properties of Water in Clay Systems
Authors: Leonard Ralph A. , Low Philip F. 
Published: August 2006

AbstractParticle 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

AbstractClay-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

AbstractThe 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.
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

AbstractClays 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

AbstractThis 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

AbstractSamples 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

AbstractThe 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

AbstractX-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

AbstractDistinction 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.