Showing papers in "Clays and Clay Minerals in 1973"
TL;DR: A preliminary survey of electronic absorption spectra of clay minerals reveals the utility of u.v. spectroscopy in the elucidation of structural, physical, and chemical properties of such systems as mentioned in this paper.
Abstract: A preliminary survey of electronic absorption spectra of clay minerals reveals the utility of u.v.-visible spectroscopy in the elucidation of structural, physical, and chemical properties of such systems. Spectra, which were obtained in the suspension, film, and single crystal states (where applic- able), are interpreted in terms of iron-associated transitions. Microcrystalline clay minerals typically show Fe(lll) in octahedral oxo-ligand geometry whereas mica-type minerals may show a range of iron species, including octahedral Fe(III), tetrahedral Fe(IlI), and octahedral Fe(I1). Iron affects the local site geometry and in "high iron" minerals may dictate layer geometry and subsequently the crystalline form.
146 citations
TL;DR: The crystal structure of a sample of talc from Harford County, Maryland, has been deter-mined by least squares refinement from X-ray diffraction photographs as mentioned in this paper, where the layers of the structure have almost monoclinic symmetry but the nearly hexagonal rings of oxygen atoms on the surfaces of the layers, formed by the bases of the silica tetrahedra, are not held in register by interlayer ions as they are in micas but are partly displaced so that the stack of layers forms a triclinic crystal.
Abstract: The crystal structure of a sample of talc from Harford County, Maryland, has been deter- mined by least squares refinement from X-ray diffraction photographs. A triclinic cell with a = 5.293, b = 9.179, c = 9.496A, a = 90'57 ~ = 98-91 ~ y = 90.03, space group cT is adopted. The layers of the structure have almost monoclinic symmetry but the nearly hexagonal rings of oxygen atoms on the surfaces of the layers, formed by the bases of the silica tetrahedra, are not held in register by inter- layer ions as they are in micas but are partly displaced so that the stack of layers forms a triclinic crystal. The hexagons of surface oxygens are distorted by a 3.4 ~ twist of the tetrahedra so that the b axis is 0.2 per cent shorter than in a structure with regular hexagons, and the twist brings the oxygen ions a little closer to the octahedral magnesium ions.
123 citations
TL;DR: X-ray diffraction patterns of garnierites indicate that most samples resemble serpentine-group minerals or a talc-like mineral, or a mixture of these forms, and give respectively 7 A and 10 A basal reflections.
Abstract: X-ray diffraction patterns of garnierites indicate that most samples resemble serpentine-group minerals or a talc-like mineral, or a mixture of these forms, and give respectively 7 A and 10 A basal reflections. From a survey of some 40 garnierites, four of predominantly serpentine type and seven of predominantly talc-like type were selected for detailed study. The talc-like garnierites exhibit little variation of the 10 A basal spacing with low-temperature heating or with immersion in liquids, though some may contain a small proportion of expandable layers. Chemical analyses show considerable deviations of octahedral/tetrahedral cation ratios from the values 3/2 and 3/4 for normal serpentine and talc minerals, and may be interpreted in terms of mixed 1:1 and 2:1 layer types, either as separate phases and/or as interstratifications, or as defect structures of various kinds. The H2O + contents of the talc-like forms of garnierite are considerably greater than that of normal talc and point to a mineral of composition 3(Mg, Ni)O·4SiO2. 2H2O or [(Mg, Ni)3Si4O10(OH)2]H2O—a talc mono-hydrate formula. The green color of garnierites is related to the NiO weight per cent and a color index is derived based on the Munsell color charts.
92 citations
TL;DR: The ammonia electrode serves as the basis of a simple, accurate method for determination of cation exchange capacity of small (ca. 50 mg) samples of clays as discussed by the authors, which is also capable of accurate measurement of CEC values on the order of 0·01 m-equiv/100 g if larger samples are used.
Abstract: The ammonia electrode serves as the basis of a simple, accurate method for determination of cation exchange capacity of small (ca. 50 mg) samples of clays. The technique is also capable of accurate measurement of CEC values on the order of 0·01 m-equiv/100 g if larger (ca. 500 mg) samples are used. The procedure, which requires saturation of the exchange sites with ammonium as in the usual methods, utilizes the electrode in the determination of ammonia released by treatment of the ammonium clay by strong base. For a Wyoming bentonite, the technique gave a CEC of 86 m-equiv/100 g with an S.D. (four determinations) of 0·83 m-equiv/100 g. Duplicate runs on the same sample by the conventional Kjeldahl method gave results of 86·0 and 85·5 m-equiv/100 g.
87 citations
TL;DR: In this article, an attempt to differentiate among some of the multiple frequencies due to OH groups was made based on the information obtained from dehydration and deuteration experiments, which indicated the presence of silanol groups.
Abstract: Infrared absorption spectra show important changes in the positions and form of the absorption bands of a film of attapulgite after it has been pumped out. An attempt to differentiate among some of the multiple frequencies due to OH groups is based on the information obtained from dehydration and deuteration experiments. The 1198 cm -~ shoulder, characteristic of attapulgite, is assigned to a Si-O vibration. When attapulgite is refluxed with 5N HCI for 5 hr the octahedral layer is dissolved. The acid attack causes the disappearance of the Si-O-Si absorption bands from attapulgite giving rise to a characteristic vibration at 1090 cm -~, as well as another absorption at 960 cm -1. The latter indicates the presence of silanol groups.
85 citations
TL;DR: The origin of these high-magnesium clays has long been attributed to either alteration of volcanic ash or the structural transformation of smectite clays as discussed by the authors, however, many of the large sedimentary deposits are more probably the result of direct crystallization adjacent to areas undergoing tropical or subtropical weathering.
Abstract: Marine and non-marine palygorskite-sepiolite deposits are found throughout the world and occur interbedded with chert, dolomite, limestone, phosphates and other non-detrital sedimentary rocks. The origin of these high-magnesium clays has long been attributed to either alteration of volcanic ash or the structural transformation of smectite clays. More recently, others have argued origin by direct crystallization (neo-formation). Recent laboratory studies support this latter concept, particularly in environments where the concentration of alumina is low, the silica concentration high, and the pH alkaline. Such an origin is proposed for the Georgia-Florida deposits in southeastern United States, since major obstacles exist against formation by alteration of volcanic ash or by transformation of smectites. Lateritic weathering during the Miocene would have favored direct precipitation of these clays in the shallow, marginal seas. The basinward increase in the MgO: Al2O3 ratio is further support. Deep weathering of crystalline rocks in northern British Honduras and Guatemala would have produced similar high silica, low alumina conditions on the adjacent submerged Yucatan Platform during the late Tertiary. The seaward increase in the MgO: A12O3 ratio, the lack of associated detrital constituents, and the absence of associated smectites strongly indicate a similar origin by direct crystallization of these Yucatan palygorskite-sepiolite clays. Some occurrences of palygorskite and sepiolite may well be related to the alteration of smectite clays or volcanic ash. However, many of the large sedimentary deposits are more probably the result of direct crystallization adjacent to areas undergoing tropical or subtropical weathering.
81 citations
TL;DR: In this article, a vesicular texture was found in the core and IP at the mar- ginal parts of each vesicle, which strongly suggest the existence of the iron analogue of saponite.
Abstract: Clayey fragments colored deep bluish-green are widely found in glassy rhyolitic tufts at Oya, Tochigi Prefecture. In room-air the color changes to black or gray within one hour and finally to brown in a few weeks. The fragments are composed of an intimate mixture of two kinds of smectite: a ferrous iron-rich smectite (IR) with bo : 9.300 ~; and an iron-poor smectite(lP) with bo = 9.030 A. Microscopic examination shows a vesicular texture and that IR occurs at the core and IP at the mar- ginal parts of each vesicle. Analysis by EPMA gave the following structural formulas: IR, (Na0,60- Ko.04Ca0.44) (Mg~.04Fe 2+ A1o02) (Sir.36All.64)O20(OH)4; IP, (Na0.~2K0.08Ca0.26) (Mgog0Fe2+.A1254) 3"98 " ' O'9a ' (SiT.66A1o.~4)O20(OH)4. IR has a much larger amount of iron in trioctahedral sites than that found in any earlier data. Acid-dissolution data, infrared absorption spectra, Eh-values, and DTA and TG curves are also given. Ferrous iron in the structure is easily oxidized in room air with loss of protons from the clay hydroxyls and with contraction of the lattice. We call the IR before and after oxidation the ferrous and ferric forms, respectively, of iron-rich saponite. They strongly suggest the existence of the iron- analogue of saponite. On exposed weathered surfaces in the field, brown fragments tend to be differ- entiated into two parts: one light yellow montmorillonite-beidellite; the other a brown incrustation due to hisingerite.
80 citations
TL;DR: In this article, the nature of freshly-precipitated and aged hydrated ferric oxides prepared by the addition of ferric chloride to KOH was investigated by the use of scanning and transmission electron microscopy, X-ray diffraction, i.r. absorption, and pH 3·0 ammonium oxalate extraction.
Abstract: The nature of freshly-precipitated and aged hydrated ferric oxides prepared by the addition of ferric chloride to KOH was investigated by the use of scanning and transmission electron microscopy, X-ray diffraction, i.r. absorption, and pH 3·0 ammonium oxalate extraction. The results show the fresh material to be essentially non-crystalline hydrated ferric oxide, which when aged at 60°C C and high pH rapidly crystallizes as goethite, without any indication of coexisting hematite. The various methods were evaluated as indices of crystallinity for aging materials. The acid ammonium oxalate method was shown to extract selectively only the non-crystalline portion of such mixtures. The use of X-ray diffraction analysis for estimating aging stage requires elimination of the preferred orientation of the goethite crystals. While both the oxalate and X-ray methods can detect as little as 2 per cent crystallinity, the oxalate method is probably superior for quantitative determinations as it depends directly on an inherent difference in the solubility of the crystalline and non-crystalline materials, rather than on a technique dependent intensity measurement. The use of the intensity of the O-H bending vibrations of the infrared absorption spectra can also potentially detect as little as 2 per cent crystallinity, but the procedure is probably less useful for quantitative determinations than the oxalate or X-ray methods because of the problem of evaluating the area under the peaks.
79 citations
TL;DR: In this article, a soil of Attica (Greece) has been studied by M6ssbauer spectroscopy and magnetization measurements in order to ascertain the nature and form of iron oxides present in it.
Abstract: A soil of Attica (Greece) has been studied by M6ssbauer spectroscopy and magnetization measurements in order to ascertain the nature and form of iron oxides present in it. The room tempera- ture spectra consist of a paramagnetic doublet and a small magnetic sextet. At liquid nitrogen tempera- ture the magnetic component increases considerably at the cost of the paramagnetic component. This behavior is typical of superparamagnetism exhibited by ultrafine magnetic particles. From the values of hyperfine parameters extracted by computer fits of the spectra, the particles can be identified mainly as a-Fe203. The theory of superparamagnetism, in conjunction with M6ssbauer and magnetiza- tion data, is discussed in detail. Application of this theory to the data for the clay fraction of the soil leads to the conclusion that the oxide particles have a size distribution with a mean particle diameter of 131 A and a width of 14 A.
69 citations
TL;DR: A simple electrostatic model has been used to demonstrate that the inner surface hydroxyls in kaolinite, dickite and nacrite are responsible for the interlayer bonding in these minerals.
Abstract: A simple electrostatic model has been used to demonstrate that the inner surface hydroxyls in kaolinite, dickite and nacrite are responsible for the interlayer bonding in these minerals. The contribution to the interlayer bonding of an individual hydroxyl hydrogen depends on the orientation of the hydroxyl group relative to the 1: 1 layer since this orientation determines the H—O interlayer distance. If this distance is much greater than the sum of the van der Waals radii, 2·60 A, there is essentially no bond. As the distance becomes less than 2·60 A, the strength of the interlayer bond increases.
65 citations
TL;DR: In this paper, the influence of crystal-chemical composition on the ease of transformation of micas to vermiculite or more smectite-like minerals is emphasized, and the swelling test, with glycerol, of Mg-saturated mineral is used to characterize the degree of transformation.
Abstract: This article emphasizes the influence of crystal-chemical composition on the ease of transformation of micas to vermiculite or more smectite-like minerals. The swelling test, with glycerol, of Mg-saturated mineral is used to characterize the degree of transformation. The main structural factors of this evolution are tetrahedral substitution of Si by Al, and total charge. There is a relation between these two factors, i.e. the lower the tetrahedral substitution, the greater can be the charge without affecting the smectite swelling behavior. In this respect there is a contrast between tri and dioctahedral micas. In the first, tetrahedral Al is so high (> 1·20 for Si4O10) that transformation into smectite must imply modification of the tetrahedral layer. For dioctahedral micaceous phyllites (illites, glauconites) where tetrahedral charge is lower, transformation can be easier. Only a lowering of total charge is needed and reduction-oxidation seems to play a very important role in this process.
TL;DR: In this paper, the diffraction patterns for mixed-layer kaolinite-glycerine-saturated montmorillonite were calculated, taking into account the differences of scattering power of the different layers.
Abstract: X-ray diffraction patterns for mixed-layer kaolinite-glycerine-saturated montmorillonite were calculated, taking into account the differences of scattering power of kaolinite and montmorillonite layers. The data were compared with the experimental results for two kaolinite-montmorillonite mixed-layer minerals. The probability parameters and the total number of layers in crystals were established. IN THE case of a mixed-layer structure consisting of layers with essentially different scattering powers, the diffraction curves must be calculated taking into account the structure factors of each type of layer. This study was concerned with an analysis of mixed-layer kaolinite-montmorillonite structures. For such structures diffraction patterns were cal- culated using the Kakinoki and Komura method (1952). The complete scattering intensity of X-rays in the reciprocal space along the axis C by the mixed-layer crystals consisting of N layers and 2 types of layers, can be expressed as follows:
TL;DR: In this paper, the adsorption of benzidine and aniline from aque- ous hydrochloride solutions by Na-, Li-, and Ca-montmorillonite and of the displaced inorganic ca- tions are determined.
Abstract: Quantitative measurements are made of the adsorption of benzidine and aniline from aque- ous hydrochloride solutions by Na-, Li-, and Ca-montmorillonite and of the displaced inorganic ca- tions. From these data, the ionic states of the adsorbed organic species are determined. Under condi- tions of controlled pH, the adsorption of benzidine increases as the pH increases, and involves mainly divalent species at pH 3.2. With aniline, monovalent and neutral species are adsorbed, and hydrogen ions also appear to participate in the reactions. Color developments of benzidine and aniline complexes of montmorillonite and hectorite are considered qualitatively in relation to the adsorption data, to various experimental conditions including the nature of the inorganic exchangeable cations, the pH, and the presence or absence of oxygen in the system, and to relevant previous work. It is hypothesized that the blue color of the benzidine com- plex is due to semiquinone formation by oxidation on montmoriUonite by the clay itself, and on hectorite by dissolved oxygen or H202, and that the yellow color under acid conditions arises from reversible formation of quinoidal cations from semiquinones. The color developments of the aniline complex are due probably to oxidation of aniline by atmospheric oxygen.
TL;DR: In this paper, it is proposed that vermiculite derives from a series of reactions whose relative rates often result in an abundance of vermiculate, and that these relative reaction rates are slow for mica dissolution, rapid for K removal, and slow for vermicule dissolution.
Abstract: Stability determinations were made by solubility methods on two trioctahedral mica-derived vermiculites. The phlogopite-derived vermiculite was found to be unstable under acid solution conditions, where stabilities of montmorillonite, kaolinite and gibbsite had previously been determined. An attempt was next made to locate a possible montmorillonite-vermiculite-amorphous silica triple point. This triple point involved conditions of alkaline pH, high pH4SiO4 and high Mg2+. These are conditions where phlogopite and biotite-derived vermiculites are most likely to control equilibria if they are stable minerals. The montmorillonite-vermiculite-amorphous silica samples went to the montmorillonite-magnesite-amorphous silica triple point, leaving no stability area whatsoever for the vermiculites. These large particle-size, trioctahedral, mica-derived vermiculites appear to be unstable under all conditions of room T and P. Arguments are presented indicating that micas are unstable in almost all weathering environments. A hypothesis is proposed that mica-derived vermiculites result from the unique way in which unstable micas degrade in these environments. It is proposed that vermiculite derives from a series of reactions whose relative rates often result in an abundance of vermiculite. These relative reaction rates are slow for mica dissolution, rapid for K removal and other reactions pursuant to vermiculite formation, and slow for vermiculite dissolution. In chemical terms, mica-derived vermiculites may be considered fast-forming unstable intermediates.
TL;DR: In this paper, the sorption of anisole and some related aromatic ethers on the interlamellar surfaces of Cu(II) hectorite has been investigated by i.r.s.r, spectroscopy.
Abstract: The sorption of anisole and some related aromatic ethers on the interlamellar surfaces of Cu(II) hectorite has been investigated by i.r. and e.s.r, spectroscopy. In addition to physical adsorp- tion, anisole forms two distinct types of Cu(II) complexes which are analogous to the type 1 and II species previously reported for benzene-Cu(II) smectite systems. These complexes can be trans- formed to type I and II complexes of 4,4'-dimethoxybiphenyl. Possible mechanisms are proposed for the oxidation process. Butyl phenyl ether formed a type II complex with Cu(II)-hectorite, no dimerization reaction was noted in this system. Phenyl ether and benzyl methyl ether form a type I ~r complex with Cu(II)-hectorite. type II analog was noted. E.S.R. spectra of each of the type II ether-Cu(II)-hectorite systems showed a sing/e, narrow band with g near the value expected for a "free spinning" electron. The type I phenyl ether and benzyl methyl ether complexes also exhibited this e.s.r, band. Ag(I) hectorite adsorbs anisole by forming exclusively a type I complex. Na(I) and Co(II) hectorite adsorb anisole by physical means only, indicating association with the silicate surface.
TL;DR: In this article, the authors used the equality of the refractive indices of the sample and of the matrix for AChr to determine some points of the anomalous dispersion curve in the neighborhood of the hydroxyl stretch- ing band (3678 era-t).
Abstract: The Christiansen effect appears in the i.r. spectrum of powders embedded in a solid, liquid or air matrix as an apparently anomalous transmittance (Christiansen peak) of the incident elec- tromagnetic radiations. The peak appears at wavelengths for which the refractive index of the sample and the refractive index of the matrix are equal (Christiansen wavelength: Ach,). On account of the great variation of the sample refractive index in the immediate neighborhood of the absorption bands (anomalous dispersion curve), one often observes the occurrence of a transmit- tance peak or of a band deformation in this spectral range. A change in the position of this transmission peak with the value of the matrix refractive index is indicative of the Christiansen effect. The equality of the refractive indices of the sample and of the matrix for AChr has been used to determine some points of the anomalous dispersion curve in the neighborhood of the hydroxyl stretch- ing band (3678 era-t). Spectral distortions caused by the Christiansen effect can be reduced by preparing the sample in such a manner that the width at half-maximum (Av~2) of the Christiansen peak is several times greater than this of the absorption band itself. Clarke's theoretical formula, which gives an estimation of Avl~2, has been qualitatively verified and thus gives an appropriate guide in the choice of the parameters which one can optimize during the sample preparation. One can reduce the Christiansen effect spectral modifications, without running the risk of modifying the sample itself, particularly by overly severe grinding.
TL;DR: In this paper, the authors examined 26 smectite samples with varying compositions and processing and found that the oxidative power increases with decreasing Li-fixation and increasing cation exchange capacity.
Abstract: The oxidative power of a smectite can be measured quantitatively by oxidation of hydro- quinone to p-benzoquinone in a clay slurry. Oxidation takes place in the presence of 02 (air) but not N2 unless Fe 3§ or Cu 2+ are the exchangeable cations. This study examined 26 smectite samples with varying compositions and processing. The oxidative power increases with decreasing Li-fixation and increasing cation exchange capacity. Li-fixation does not depend upon the tetrahedral A1. The cation exchange capacity can decrease markedly by mere storage in water. The oxidation proceeds principally on the surface by adsorbed oxygen molecules or radicals. A mechanism is proposed. With Fe 3§ or Cu z§ present, even under N2, oxidation occurs via electron transfer. With smectites containing Fe z§ both the Fe and the hydroquinone are oxidized in the same reaction.
TL;DR: The structure of 2M2 mica was defined by high voltage electron diffraction as mentioned in this paper, and the cell parameters are: a = 8-965, b ~ 5-175, c = 20.31 A, fl = 100 ~ 40', Z = 4, space group C2/c.
Abstract: The structure of a dioctahedral 2M2 mica was defined by high voltage electron diffraction. The cell parameters are: a = 8-965, b ~ 5-175, c = 20.31 A, fl = 100 ~ 40', Z = 4, space group C2/c. Despite the peculiar character of the layer dispogition (or 4 as ~r~ as) , the oxygens of the layers are packed according to the cubic law. Consequently, the interlayer cations K have a trigonal prismatic coordination. The angle of tetrahedral twist is 11 ~ 20'. The interatomic distances T-O indicate ordered replacements of AI for Si.
TL;DR: In this paper, the initial degree of supersaturation with respect to amorphous iron(III) hydroxide is the key factor governing particle size distribution, which in turn governs the appearance, stability and crystallinity of the hydrolyzed product during aging.
Abstract: Fe(ClO,)3 solutions of different concentration and acidity were studied to search for the factors governing their appearance and stability during aging and to elucidate the mechanisms for the formation of amorphous and crystalline iron(III) hydroxides from slow hydrolysis. It was found that dilute solutions (0.001M or lower) rapidly hydrolyzed to clear sols after a brief induction period. With an increase in iron(III) concentration, one could notice gradual increases in the induction period, tur- bidity and particle size. Thus, solutions 0.006M to 0.01M in iron(III) developed into dense, cloudy, yellow suspensions impervious to light. The polymeric iron(III) species in the aged 0-02M solution were primarily large particles that settled under gravity, resulting in a suspension of low turbidity. It was also observed that in dilute solutions, the initial polymerization product was amorphous iron(III) hydroxide which yielded X-ray diffraction peaks for FeOOH only after prolonged aging or not at all. In 0.01 and 0.02M solutions, however, crystalline FeOOH was the major product from the very beginning of polymerization. The results suggest that the initial degree of supersaturation with respect to amorphous iron(III) hydroxide is the key factor governing particle size distribution, which in turn governs the appearance, stability and crystallinity of the hydrolyzed product during aging. The addition of HCIO, to dilute Fe(CIO,)3 solutions decreased, whereas the addition of NaOH to concentrated solutions increased, the degree of supersaturation and, thus, induced changes in induc- tion period, appearance, stability and crystallinity of the hydrolyzed product accordingly.
TL;DR: In this article, the cation exchange process between trisethylenediaminecobalt(llI) and Na + on montmorillonite was studied by atomic absorption spectrophotometry, X-ray diffraction, differential thermal analysis, and nitrogen sorption at 78~.
Abstract: The cation exchange process between tris(ethylenediamine)cobalt(llI) and Na + on mont- moriUonite was studied by atomic absorption spectrophotometry, X-ray diffraction, differential thermal analysis, and nitrogen sorption at 78~ The exchange of Co(en)33+ for Na § was found to be extremely favorable, with a tendency toward segregation of the two kinds of cations in the mixed clays studied. Small amounts of Co(en)a § were found to lower the nitrogen sorption capacity of Na § mont- morillonite while clays with high Co(en)3 +a content had greatly enhanced sorption. An explanation is offered in terms of a dual role of the Co(en)3 +~ in determining the kind and amount of nitrogen sorption in the exchanged montmorillonite.
TL;DR: In this paper, X-ray diffraction analysis of mixed alkylammonium-exchanged smectite revealed segregation of different ion species into randomly ordered layers, which is explained by the hydration properties of cations as well as the energy requirements of layer expansion.
Abstract: X-ray diffraction analysis of mixed alkylammonium-exchanged smectite revealed segregation of different ion species into randomly ordered layers. Vermiculite, however, showed segregation into crystallites, a behavior attributed to clay inhomogeneity. Ion segregation is explained by the hydration properties of cations as well as the energy requirements of layer expansion. Quaternary ammonium ions of different size were used to exchange ethylammonium-clays, and the effectiveness, as well as steric hindrance, of cation size in ion exchange was demonstrated. Layer charge density was related to the degree of ease of large cation adsorption. Basal spacing in suspension was found to be important in determining the preference of vermiculite for certain cations, while more freely-expanding, lower layer charge smectite did not demonstrate this phenomenon.
TL;DR: In this article, the < 1 µm size fraction of one sample of corrensite-like material has been studied in detail and X-ray diffraction data and chemical analysis indicate that this specimen is a regular or nearly regular interstratification of chlorite and dioctahedral smectite.
Abstract: Corrensite or ‘corrensite-like’ minerals occur in dike-intruded shales and siltstones of the Montana Group and Colorado Group (Early Cretaceous) in Western Montana. The < 1 µm size fraction of one specimen of this “corrensite-like” material has been studied in detail. X-ray diffraction data and chemical analysis indicate that this specimen is a regular or nearly regular interstratification of chlorite and dioctahedral smectite. Also described are other samples, which contain corrensite and additional phases. These samples were taken at several localities where basic dikes have intruded these shales and siltstones.
TL;DR: In this article, the authors show that the distribution of effective negative charges (tetrahedral negative charges less positive octahedral charges) is also at least partially ordered, and demonstrate a two-dimensional organization of the compensating cations and of the water molecules in the interlamellar layer.
Abstract: Abnormal scatterings of X-rays take place between Bragg spots. Their study in hydrated Mg- and Ni-vermiculites shows that they appear in reciprocal space in the form of modulated lines, elongated along the Z* axis. These scatterings demonstrate a two-dimensional organization of the compensating cations and of the water molecules in the interlamellar layer. In such ordered domains, the cations are situated at the nodes of a biperiodic centered lattice with parameters 3a,b. The distribution of compensating cations must conform with the charge distribution which they neutralize; it can therefore be concluded that the distribution of effective negative charges (tetrahedral negative charges less positive octahedral charges) is also at least partially ordered. Ненормальное рассеивание рентгеновских лучей происходит между брэгговскими пятнами. Их исследование в гидратированном М§ и № вермикулитах показало, что они появляются в сопряженном пространстве в форме модулированных линий, удлиненных по оси Z*. Это рассеивание демонстрирует двухмерную организацию компенсирующих катионов и присутствие водяных молекул в интерламинарном слое. В таких хорошо организованных владениях катионы находятся на узловых точках двуякопериодически центрированной решетки с параметрами За, Ь. Распределение компенсирующих катионов должно согласоваться с распределением заряда, который они нейтрализуют; поэтому можно заключить, что является необходимым распреде¬ление эффективного отрицательного заряда (тетраэдральные отрицательные заряды минус октаэдральные положительные заряды).
TL;DR: In this article, the adsorption sites are of two types: lattice hydroxyl groups located at crystal defects and edges, and organic matter adsorbed by the clay.
Abstract: The adsorption of trace quantities of Cu (3·89 × 10−6 to 3·00 × 10−4 M) by a bentonite clay from calcium acetate solution was studied over the range of pH 4·27–5·87. The data were fitted to an existing adsorption equation and the ‘best’ values of the adsorption parameters were calculated. The proton, cupric ion and mono (hydroxy) cupric complex were found to be the adsorbed species. The adsorption sites are of two types. It has been postulated that the majority of sites are lattice hydroxyl groups located at crystal defects and edges. The remainder arise from organic matter adsorbed by the clay and are the more important in the adsorption of Cu at very low metal concentration and at pH <5·4. The implication of the results on the potential use of bentonite clay to remove trace amounts of Cu from mine waste waters is considered briefly.
TL;DR: In this paper, the growth of order with increasing ferric iron content has been assessed by comparison with theoretical calculations for random and most ordered interstratified structures, and the depression in rates of K release due to oxidation has been confirmed.
Abstract: Artificial weathering of biotites, which contain various levels of structural ferric iron, by NaCI and NaBPh4 solutions produces minerals and structures similar to those described for naturally weathered biotites. Oxidation of structural iron leads to K removal from alternate layers and develop- ment of hydrobiotite. The growth of order with increasing ferric iron content has been assessed by comparison with theoretical calculations for random and most ordered interstratified structures. There is evidence for the existence of two layer types in biotite prior to oxidation. The depression in rates of K release due to oxidation has been confirmed.
TL;DR: In this paper, the X-ray powder diffraction was used to examine the serranine and talc-like gamierites and to identify the mixed crystallizations possibly existing in the initial minerals.
Abstract: Serpentine- and talc-like gamierites described in Parts I and II were heated at various temperatures up to about 1000~ and after each treatment were cooled and examined by X-ray powder diffraction. The serpentine-like garnierites at about 550~ the temperature at which rapid dehydroxy- lation begins, formed a highly disordered phase. When the NiO content was low (approximately < 20 wt%), the disordered phase transformed directly to an olivine phase around 800~ but when the NiO content was higher, various transitional phases were formed before an olivine phase appeared around 1000~ A sepiolite-like phase was obtained with one sample around 800~ and several samples showed face-centered cubic modifications between 900 and 1000~ The talc-like garnierites with low NiO content formed an enstatite phase around 800~ directly following the dehydroxylation reaction, but with high NiO contents an olivine phase became increas- ingly prominent between 850 and 1000~ Identification of the mixed crystallizations possibly existing in the initial minerals is scarcely feasible on the basis of the products formed up to 1000~
TL;DR: In this article, the authors presented new information relating to the hydrothermal stability, lattice parameters, and adsorptive, electrical, and catalytic properties of synthetic and natural faujasite.
Abstract: New information is presented relating to the hydrothermal stability, lattice parameters, and adsorptive, electrical, and catalytic properties of synthetic and natural faujasite. Present concepts concerning the nature and relationship of synthetic and natural faujasite are restated to be consistent with the experimental evidence and the developed physical model. The major structural and physicochemical properties reflect the close similarities and smooth gradations expected of substitutional members of a continuous series. The existing division of the range (2–6) of SiO2/Al2O3 mole ratios (S/A) at 3 into two compositional subranges is shown to be unjustifiable and rather misleading. Individual compositions from these two subranges do not represent distinctly different zeolite species; instead, it is demonstrated that they are members of a continuous series with smoothly changing properties over the studied range of SiO2/Al3O3. Some of the properties of the natural mineral faujasite are found to be very similar to those of the synthetic analogs with the same SiO2/Al2O3 mole ratio.
TL;DR: Wiewiora and Brindley as mentioned in this paper investigated the relationship between the different hydration states of halloysite-water complexes which were formed by washing various intercalation complexes of the mineral and compared with the drying behavior of naturally hydrated haUoysite.
Abstract: INTRODUCTION MANY alkali ynetal salts of short chain fatty acids have a strong affinity towards the formation of interlayer complexes with kaolin minerals (Weiss et al., 1963). The complexes of kaolin minerals with potassium acetate, KOAc, in particular have been the subject of much investigation: e.g., Wada (1959, 1961, 1965); Deeds et al. ( 1966); Wiewiora and Brindley (1969). One of the observations made in these studies is that the removal of intercalated KOAc by washing results in different products for the different kaolin minerals. Halloysites have the spacing of the fully hydrated form (10.1 A) restored when intercalated KOAc is removed in this way, regardless of whether they had been intercalated with the salt while in this form (Wada, 1961). Nacrite also forms a water complex as a result of the washing of its KOAc complex (Wada, 1965; Deeds et al., 1966). The nacrite hydrate formed in this way has a basal spacing of 8.4 A. Kaolinite and dickite do not form water complexes following intercalation with KOAc and the subsequent removal of the salt by washing, although it has been observed that the original structural order of kaolinite may not be preserved by these treatments (Wiewiora and Brindley, 1969). This report concerns a part of an investigation of the relationship between the different hydration states of halloysite (Churchman et al., 1972). The behavior on drying of halloysite-water complexes which were formed by washing various intercalation complexes of the mineral were compared with the drying behavior of naturally hydrated haUoysite.
TL;DR: The basal spacings of long chain n-alkanol complexes of nontronite saturated with Li +, K + Mg ~+, Ca ~+, Sr 2+ and Ba ~+ were measured for temperatures increasing from--70~ up to 130~ as mentioned in this paper.
Abstract: The basal spacings of long chain n-alkanol complexes of nontronite saturated with Li +, K + Mg ~+, Ca ~+, Sr 2+ and Ba ~+ were measured for temperatures increasing from--70~ up to 130~ With rising temperatures the complexes rearrange from a low temperature form into a high temperature form. In the low temperature form the alkyl chains of the alkanol molecules form bilayers with their chain axes perpendicular to the silicate layers. The chains may not be in all cases in the planar all trans conformation but in special 'kink'-conformations. The transition into the high temperature form is explained by cooperative transition from a form with a low number of ~jogs' to one with a high number of 'jogs' and 'kinks'.