Showing papers in "Clay Minerals in 1971"
TL;DR: The plastic properties of clays are sufficiently variable to offer a simple but practical aid to identification as discussed by the authors, which can be done by using their Atterberg 'plastic limit' and "plasticity index' values as parameters for an identification chart.
Abstract: The plastic properties of clays are sufficiently variable to offer a simple but practical aid to identification. This can be done by using their Atterberg 'plastic limit' and 'plasticity index' values as parameters for an identification chart. The advantages and disadvantages of the technique are discussed, and results for a wide variety of clay minerals, particularly industrial clay types, are illustrated. A brief summary is also given of the effect of non-clay impurities, and reference is made to the correlation of Atterberg limit values with other physical properties of clays.
93 citations
TL;DR: In this paper, the authors studied the effect of different cations on the yield of Laponite clay at a standard level of flocculation and found that the break in the yield value curve occurs when enough clay is present to form a card-house structure.
Abstract: Dispersions of Laponite clay in various electrolyte solutions have been studied. In the total absence of electrolyte the synthetic clay forms a sol at 2 ~ con- centration. All cations cause gelling and flocculation. It has been found that for any given clay concentration the yield value of the dis- persions at equivalent flocculation level is the same for all electrolyte solutions, making it possible to study all types of dispersions at a standard level of flocculation. At standard level of flocculation, the yield values have been found to follow exponen- tial relationships with clay concentration with a break in the curves occurring at about l '6 ~ clay concentration. It is postulated that the break in the yield value curve occurs when enough clay is present to form a card-house structure. The plastic viscosities show a linear relationship with concentration and indicate high effective dispersed volume fractions at low clay concentrations. When comparing the flocculating effects of different cations at fixed clay concen- tration, an empirical relationship has been found between cation concentration giving standard flocculation level, cation valency and radius.
38 citations
TL;DR: More than twenty new organic complexes of halloysite have been prepared and one hundred and twenty-seven compounds were tested as discussed by the authors, and the best explanation of the existence of these metastable complexes seems to lie in the ability of some organic molecules to form hydrogen bonds with the halloy site structure, about which insufficient knowledge is available to allow quantitative evaluations to be made.
Abstract: More than twenty new organic complexes of halloysite have been prepared and one hundred and twenty-seven compounds were tested. Results are compared with those of earlier studies and use is made of recent findings concerning particle morphology and interstratification effects to interpret the results. The compounds which form complexes with halloysite are polar, and are usually either acids or bases. Their molecules usually contain two functional groups (preferably —OH and/or —NH2), are relatively small and have one functional group per two carbon atoms, but do not usually include cyclic or aromatic types. The best explanation of the existence of these metastable complexes seems to lie in the ability of some organic molecules to form hydrogen bonds with the halloysite structure, about which insufficient knowledge is available to allow quantitative evaluations to be made.
31 citations
TL;DR: A variety of slevensite was collected at the Obori mine, Yamagata Prefecture, Japan as mentioned in this paper, where the structural formula is (Fe0.04 Mgs.0.20) Si8.01 020.4.
Abstract: A variety of sl~evensite was collected at the Obori mine, Yamagata Prefecture, Japan. Analysis shows close agreement with published data for stevensite. Chemical composition : SiO2 52' 76 ~; A1203 trace; Fe203 0"38 ~; MgO 23'67 ~; MnO 1"57~o; CaO 2.19~; Na20 0"37~; K20 0"00~; H20 + 6'52~; H20- 12"38~; Total 99.84~. The structural formula is (Fe0.04 Mgs.31 Mn0.20) Si8.01 020.00 (OH)4.00'Ca0.36, Na0q0. This specimen shows an interstratified structure of dehydrated and hydrated layers, the former caused by dehydration of the interlayer water, although stevensite essen- tially contains a non-swelling layer and shows interstratification. The intensities and spacings of the 00l reflections change successively with changes in humidity. When treated with water andglycerol, the 00l reflections are similar to those of montmorillonite. The DTA and TG curves are similar to those of stevensite and an interstratified mineral of talc and saponite.
29 citations
TL;DR: In this article, X-ray powder diffraction patterns of kaolinites have been studied with especial reference to the region of the 02, 11, 11 band with a focus on the region in which the disorder between and within layers of a kaolinite can be detected.
Abstract: X-ray powder diffraction pattern_s of kaolinites have been studied with especial reference to the region of the 02, 11, 11 band. Satisfactory correlations with calculated patterns based on the layer structure of dickite can be achieved for a range of kaolinites if account is taken of disorder between and within layers. Some indication of the amount of disorder within a kaolinite can be obtained.
23 citations
TL;DR: In this article, it is suggested that large amounts of A1, Fe and Si carried in solution by fresh water are chemically precipitated as hydroxide gels in the brackish water environment of estuaries and deltas, and these gels are subsequently deposited in the neighbouring seas, where they become parental material for the neoformation of clay minerals and various other silicate and iron minerals.
Abstract: It is suggested (1) that large amounts ofA1, Fe and Si carried in solution by fresh water are chemically precipitated as hydroxide gels in the brackish water environment of estuaries and deltas, and (2) that these gels are subsequently deposited in both the brackish water environment and in the neighbouring seas, where they become parental material for the neoformation of clay minerals, and various other silicate and iron minerals. The types of neoformed minerals will depend upon both the com- position of the parental gels and the physico-chemical milieu of their crystallization. Evidence is discussed supporting this hypothesis from the following sources (1) the concentrations of A1, Fe and Si dissolved in fresh water and in sea-water, (2) experi- mental work on the crystallization of alumino-siliceous gels, and (3) a study of the precipitation of Si from the waters of the Mississippi River delta. Because of the unusual sediment pattern of present times, this source of neoformed clay minerals and other minerals contributes only a small proportion of the sediments of the brackish parts of estuaries, deltas and the adjacent seas, which are dominated by fine-grained continental detritus. In earlier geological eras, when the world's river systems carried only relatively minor amounts of fine-grained continental detritus, this source of neoformed minerals is likely to have contributed a considerable proportion of the fine-grained sediments of these areas of sedimentation. Three possible examples are discussed.
20 citations
14 citations
TL;DR: In this article, the authors studied the possible arrangements of the amino acid molecules in the interlayer space and derived the basal spacings of the complexes, based on the assumption that the electropositive groups NH4a penetrate into the holes formed by the basal oxygens of the silicate.
Abstract: A B S T R A C T: Vermiculite single crystals immersed in aminoacid solutions of varying concentration and pH, form complexes characterized by discrete basal spacings. Organic molecules enter in the interlayer space as cations and as dipolar ions through mechanisms of ion exchange and dipole adsorption. The basal spacings of the complexes were recorded. Based on these results the possible arrangements of the aminoacid molecules have been discussed.The main assumptions used are: (a) the electropositive groups NH4a penetrate into the holes formed by the basal oxygens of the silicate; (13) the C-N bonds are perpendicular to the silicate sheets; (c) the hydrogen atoms of the ---CH2 groups are directed towards the sheet surfaces; (d) the ---COO- and --COOH groups are located in the middle plane of the interlayer space, halfway between the negative structural charges; and (e) double hydrogen bonds are formed between --COOH groups belonging to organic cations adsorbed onto opposite surfaces. In solutions of higher concentration the crystals swell to the gel state. This phenomenon is due to: (a) the different nature of interlayer cohesion after substitution of the inorganic cations by the aminoacid cationic form; and (b) the appearance of repulsive forces between --COO- groups of adsorbed dipoles, that overcome cohesive forces.
14 citations
TL;DR: In this paper, the authors investigated the properties of straight chain, primary, aliphatic alcohols from methanol to n-decanol with Ca-mineral and Na-montmorillonite from the liquid and vapour phases.
Abstract: Complexes formed by straight chain, primary, aliphatic alcohols from methanol to n-decanol with Ca- and Na-montmorillonite from the liquid and vapour phases, have been investigated by X-ray techniques. Satisfactory complexes are formed more readily by the Ca-mineral and from the liquid phase rather than from the vapour phase. Molecular configurations of the adsorbed molecules are suggested consistent with the experimental data. The importance of cation-dipole interactions for the lower members of the series is stressed.
11 citations
TL;DR: In this article, the orientation ratio of platy particles in a clay is defined by an orientation ratio which can be derived analytically from optical birefringence as well as from X-ray diffraction data Measurements on kaolin slurries consolidated by increasing loads were used to verify that orientation ratios obtained experimentally by these two methods are in fact equivalent.
Abstract: The spatial arrangement of platy particles in a clay is defined by an orientation ratio which can be derived analytically from optical birefringence as well as from X-ray diffraction data Measurements on kaolin slurries consolidated by increasing loads were used to verify that orientation ratios obtained experimentally by these two methods are in fact equivalent In contrast it was found that particle orientation cannot be assessed objectively from electronmicrographs alone A combined optical-X-ray study of two natural clays (London Clay and Lias Clay) revealed that the kaolinite crystals are oriented only slightly more than the illite crystals, and showed that the correspondence between optical and X-ray measurements is also valid for natural clays
10 citations
TL;DR: In this article, the authors measured the amount of swelling by measuring by X-ray diffraction the separation of the elementary silicate layers in the gel-like crystals and then applied pressure on the gels along the swelling direction to obtain a direct measure of the swelling pressure.
Abstract: Vermiculite single crystals swell to the gel state as a consequence of treatment with concentrated solutions of 7-aminobutyric acid. The amount of swelling was determined, by measuring by X-ray diffraction the separation of the elementary silicate layers in the gel-like crystals. By application of pressures into the gels along the swelling direction, a direct measure of the swelling pressure is obtained. The relation between swelling pressures and equilibrium interlayer distances is a function of both cationic concentration and dielectric constant of the solution. Measured swelling pressures are consistent with a model based on formation and interaction of diffuse doable layers of aminoacid cations around the silicate particles, these having a Stern layer of an approximate thickness of 5 A. The specific chemical adsorption potential of the system has been estimated as q~ = 3"3 + 0.2 Kcal/mol.
TL;DR: In this paper, the Stafford Clay marker bed from the Middle Coal Measures of North Staffordshire and the Woolhope Bentonite from the Silurian, Wool-hop Limestone near Woolhop in Herefordshire are described.
Abstract: Two clay deposits, the Stafford Clay marker bed from the Middle Coal Measures of North Staffordshire and the Woolhope Bentonite from the Silurian, Woolhope Limestone near Woolhope in Herefordshire are described. These clays contain mixed-layer clay minerals which have been separated by sedimentation for mineralogical and chemical analysis. Both minerals are shown to be mica-montmorillonites with MacEwan stacking parameters PA = 0·59, PAA = 0·44 and PA = 0·56, PAA = 0·70 respectively. In both cases the average layer charge (1·22 and 1·46) is intermediate between that of montmorillonites and micas but the exchangeable cation layer charge (1·07 and 1·27/montmorillonite layer) and fixed cation layer charge (1·32 and 1·63/mica layer) of the component layers are higher and lower respectively than the normal range of montmorillonites and micas. Some chemical data are given for the raw material which yielded these minerals and for associated and related rocks. In particular K, U and Th determinations permit a discussion of the natural gamma-ray flux which is sufficiently more intense than that of the associ~.ted sediments to permit its detection by scintillation counter in the field.
TL;DR: Partial molal voltmae of Ca-montmorillonite, apparent molal volume of silica gel in water and of Ca -montmoroniite in ethanol-water mixtures, were determined using pycnometer density measurements as discussed by the authors.
Abstract: Partial molal voltmae of Ca-montmorillonite, apparent molal volume of silica gel in water and of Ca-montmorillonite in ethanol-water mixtures, were determined using pycnometer density measurements. No electrostriction of water was observed with silica gel but took place in Ca-montmorillonite thus indicating the principle role of surface charges in stricting water. In ethanol-water mixtures alcohol molecules were salted out at low alcohol concentration, but they started reaching inner zones near the clay surfaces when their mole fraction in solution was increased beyond the value of 0·55.
TL;DR: In this paper, the authors show that fixation of K by soil clays and selected reference clay minerals was induced by dry heat and hydrothermal procedures, at 100~ 200~ and 380~ respectively, at all temperatures.
Abstract: Fixation of K by soil clays and selected reference clay minerals was induced by dry heat and hydrothermal procedures, at 100~ 200~ and 380~ Appre- ciable amounts were fixed at all temperatures. In the cases of the samples treated hydro- thermally the amounts fixed increased with pressure. Fixation by dry heating at 380~ was significantly greater than at 100~ and 200~ respectively. Fixation under hydrothermal conditions increased in order 380~ > 200~ > 100~ Reductions in cation exchange capacities (and surface areas) were associated with fixation, indicating that some fixation was due to ion exchange. Changes in mineralogy in some of the samples also support the conclusion that ion exchange was partly respon- sible for fixation. Some of the fixation under hydrothermal conditions was due to the formation of insoluble K-compounds - as for example the synthesis of a new mineral when one sample was treated. The lattice-iron content of the clays may have influenced their hydrothermal behav- iour. Thus the Princes Town Clay (> 7"5 ~ lattice-iron) and three nontronites (~ 7.5 lattice-iron) showed appreciable lattice collapse after hydrothermal treatment, while Wyoming bentonite and hectorite (< 3' 5 ~) lattice-iron) showed no collapse at all. The degree of crystallinity of the mineral may also have influenced its hydrothermal reaction. For example, the highly disordered soil kaolinite (St John's) was much more reactive than the more ordered Georgia kaolinite. Also, the more-ordered refer- ence clays fixed relatively less K at 380~ than the less-ordered soil clays.