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Several kaolinite samples were selected for x-ray diffraction studies on the basis of their paper-coating ability. The evaluation of the kaolin clay for paper coating was based on a series of empirical tests including viscosity, resistivity, brightness, and particle-size distribution. The crystallinity of the kaolinites was determined by use of x-ray powder diffraction patterns. In all samples that were good paper coaters, the crystallinity was well developed. Other samples which were poor paper coaters either had poor crystallinity, or, if they had good crystallinity, contained montmorillonite. Crystallinity is not a function of the size fraction. Generally, if the crystallinity is good in the raw sample, then the crystallinity is also good in the < 0.25 micron fraction. Suitability of kaolinite clay for paper coating varies directly with the perfection of crystallinity and indirectly with the montmorillonite content. Both of these variables can be determined by use of x-ray diffraction data.

Calcium hydroxide was allowed to react with various clays and other silicates at slightly elevated temperatures for several months. The reaction products were examined by x-ray, DTA, and electron microscopy, and were shown to be poorly-crystallized calcium silicate hydrates of the tobermorite family and calcium aluminate hydrates. Quaternary phases were not detected, but some isomorphous substitution probably occurs. The extent of reaction was shown to be such that under appropriate conditions almost all of the clay mineral was decomposed. Electron micrographs of the reacted materials indicated that attack occurred from the edges of the particles, and in general the remaining unattacked portion of the clay did not suffer appreciable loss of crystallinity. It was postulated that the reaction involves progressive dissolution of the mineral at the 'edges of the particles in the strongly basic environment maintained by calcium hydroxide solution, followed by separate precipitation of the reaction products. In these experiments the calcium silicate hydrate generated by the reaction between lime and quartz was uniformly CSH(gel); reaction with kaolinite and montmorillonite produced either CSH(gel) or CSH(l) depending on the conditions of the reaction. At 60 C the alumina-bearing phase was tricalcium aluminate hexahydrate; at lower temperature the phase produced was a hexagonal material closely resembling 4CaO.Al203.3H20 but retaining a constant 7-6A. basal spacing regardless of its state of wetness or dryness. It was found that under appropriate conditions the formation of CSH(l) resulted in as effective a cementation as did the formation of CSH(gel).

This work was undertaken to study the effects of base paper structure on the coated surface characteristics by observing fiber interfaces of coating layers with a scanning electron microscope. In order to observe fiberinterfaces of coating layers, it was required to separate the coating layer from the base paper without destruction. The author applied the following techniques for kaolinite coated papers of various binder compositions. (1) The coated paper of which surface was backed with a polystyrene plate was placed in 72% sulfuric acid for 1.52-hr. The base paper dissolved out leaving the coating layer backed with the polystyrene plate. This technique was found satisfactory for the paper coated with latexstarch-PVA binder. (2) For the papers coated with latex-starch binders, coating layer were destroyed in some degree during 72% sulfuric acid.treatment. Instead of 72% sulfuric acid treatment., Celluase-CEDA treatment was found effective for these papers.(3) Scanning electron micrographs of fiber interfaces of coating layers were proved especially of value in studying the correlation between base paper structure and penetration of coatings.

We have been unable to confirm the recent report that kaolinite catalyzes the polymerization of aqueousd- andl-aspartic acid at different rates. In experiments wheredl-Asp was used, no induced optical rotation was found in the reaction solution. No evidence for polymer (or other product) formation was found whenl-Asp-2-14C was used, and products were searched by paper chromatography and X-ray film autoradiography. Asp is adsorbed by kaolinite, but no selectivity for one or the other enantiomer was observed.

From abstract: This paper is a continuation of the study of the kaolin minerals, in the first part of which, published in 1931, the kaolin minerals kaolinite, dickite, and nacrite were described. In that paper the application of chemical, optical, X-ray, and dehydration methods to the investigation of clay materials were discussed. The present study shows that halloysite is a fourth mineral of the kaolin group, closely related to but distinct from kaolinite. The chemical, optical, X-ray, and dehydration properties of a representative group of halloysites are recorded, all these being new data determined by the authors on separate portions of single samples whose purity has been carefully tested.

In the earlier papers (I and II, Frank-Kamenetzkij et al., 1966, 1968) data regarding the structural and facial changes in kaolin group minerals under conditions of interaction with hydrothermal chloride solutions of K, Na, Ca, Mg at P = 900 kg cm−2. T = 200–500°C were dis- cussed. In the present paper the results of these investigations are summed up. The diffractometrical, electronographic and electron microscopic investigations of initial, intermedial and final phasis mainly of layered silicate and aluminous silicates show a cristallographic inheritance of structures during the transformation of kaolinite into montmorillonite, micas and mixed layered facies (rectorit, tosudit etc.) This is seen in the retention of the main features in the basal plane, in the character of population of the octahedral positions, in the tendency to retain the sequence of alternation and imposition of layers (polytype), and in the processes of deformation that the structures of the initial minerals undergo during such changes. The wide participation of ordered and disordered mixed-layered structures in these reactions is the result of structural changes by transformatical means. At the same time, the chemical nature of the medium exerts considerable influence on the course and nature of the resulting structures. Thus, the mechanism of transformational thermal changes of aluminium silicates, which is already known for “dry-systems”, is observed to a great extent in the case of complex polycomponental systems under H2O pressure and is characterised by the specific individual features discussed in this paper. [Russian text ignored].

This paper was prepared for the Society of Petroleum Engineers of AIME Symposium on Formation Damage Control, to be held in New Orleans, La., Feb. 7–8, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Many hydrocarbon producing formations contain clays that can influence primary production as well as stimulation primary production as well as stimulation results. The clays that have frequently been found in these horizons are montmorillonite, mixed layer, illite, kaolinite and chlorite. A correlation has been developed that indicates the types of clays that may be expected in certain areas and depth of burial in the Gulf Coast region. All of the above noted clays are capable of migrating and causing permeability damage when a formation is permeability damage when a formation is contacted by a foreign water. Normally, waters foreign to a formation alter the ionic environment which is responsible for the clays being dislodged from their original positions. A change in the swelling or water retention of montmorillonite and mixed layer clays enhances their probability of migrating. Thus, any time a clay is present, it can be assumed that permeability damage may occur if the proper precautions are not observed. The degree of damage will depend upon the concentration and types of clays present, their relative position in the rock and the severity of the ionic environmental change. Clay problems should be considered by the well operator in the initial planning of the well. Muds and cement planning of the well. Muds and cement slurries can be treated with potassium chloride to minimize damage when fluid is lost to the formation. The selecting of the correct perforating fluid is also important. Stimulation treatments should be redesigned to fit formation conditions as nearly as possible. Chemicals such as potassium chloride or ammonium chloride may be added to water to minimize total environmental changes when water is used in fracturing procedures. Surfactants are present in most stimulation fluids and these chemicals are capable of being adsorbed by clays and other silicate surfaces which may influence the effectiveness of a treatment. The kind of surfactant to use in any stimulation procedure should be of the type that leaves all procedure should be of the type that leaves all silicate surfaces water wet. An oil wet formation can trap water in the pores to greatly reduce the flow of oil or gas.

The present paper presents the mineralogical composition of sediments from the Spanish Wealdian facies, selected from four stratigraphic sections of several regions in the Southern Cordillera Iberica. Three of these sections show an irregular alternation of kaolinite rich sandy and silty-clay beds. The fourth section which contains calcareous layers, is very important from a geological point of view, because it is located where the structures of two ranges, the Iberian and the Betics, converge. The clays of about 80 samples from these sections always consist of illite, kaolinite and interstratified clay minerals. The sandy layers also Contain quartz, as well as potash and calcic-sodic felspars. The fine fraction (< 2 #m) is composed of kaolinte, between pM and T types, swelling illite and randomly interstratified clay minerals of the t~)pe (10r14~), richer in 10 A layers. From the mineralogical and crystalchemical data and field observations, it is deduced that these sediments are mainly detrital. This and the layer alternation suggest, for the Upper Jurasic and Lower Cretaceous (Wealdian facies), a climate alternating from biostatic to rhexistatic. Alternating laterization and erosion might supply the materials to the Wealdian sedimentary basin.

Numerous workers have examined the weathering products of soil minerals and have proposed empirical weathering sequences. The present paper outlines the development of a thermodynamic model that predicts in a systematic way several mineral transformations that can occur in soils. According to this model, the stability of primary minerals increases in the order: Na-glass, K-glass, pyroxene, analcime, anorthite, low albite, muscovite, microcline, and quartz. The stability of secondary clay minerals depends on soluble silica. At pH 6 with high silica (≃ 10⁻³M) the order of increasing stability is: chlorite, halloysite, gibbsite, illite, dickite, beidellite, kaolinite, and montmorillonite; at low silica (≃ 10⁻⁵M) the order is: chlorite, halloysite, illite, beidellite, montmorillonite, dickite, kaolinite, and gibbsite. The stability of both primary and secondary minerals increases with pH. The observed weathering of volcanic ash agrees well with the predictions of this model. The model makes use of important thermodynamic data accumulated for soil minerals and helps to pinpoint deficiencies in these data. The need to examine the kinetics of mineral transformations in soils in greater detail also becomes obvious from this model.

All MDO-polytypes (i.e. regular polytypes) of trioctahedral, dioctahedral and monoctahedral 1:1 phyllosilicates are derived from their OD-character using the results of our preceding paper. The terms 'simple polytype', "standard polytype' and 'regular polytype' turn out to be synonyms of the term 'MDO-polytype" which has the advantage of being exactly defined. The method used to obtain the MDO- polytypes is also applicable to more complicated cases.

About 250,000 acres of soil with fragipan have been mapped in Nova Scotia. The fragipan horizons of two soils (Tormentine and Debert) reported in this paper are typical for the province. They have high bulk densities and low saturated hydraulic conductivity. They are also low in organic carbon and free oxides. They are high in fine sand and silt but low in clay, and the fragments of fragipan are readily slaked in water. Mica, chlorite, vermiculite, and kaolinite were found in the clay fractions of both soils throughout the two profiles. A moderate amount of smectite was found in the clay fractions of the Ae horizon of Debert but not in the Tormentine profile. A significant amount of clay increase in both fine and total clay fraction was found in the Bf horizon of the Tormentine soil and the Bmgj and Btx horizons of the Debert soil, and results from translocation or lessivage. The brittleness and other associated properties of the fragipans were attributed to clay bridges linking coarser particles, which were shown in the scanning electron microscope pictures.

A method of precipitation in homogenous solution has been used for the synthesis of kaolin minerals at room temperature. The method consists essentially in producing conditions for which a sufficiently slow rate of precipitation is maintained. In the particular case described in this paper, the conditions for homogenous precipitation are obtained by addition of an anion exchange resin in the OH form to an acidic solution (pH ≈ 4) of sodium silicate and aluminium chloride or acetate.The mineral species synthesized in each particular case depend on the kind of anions present in the original solution (chloride or acetate) and also on the nature of the exchange resin used.

Previous work has demonstrated that the degree of crystal perfection in kaolinite can be correlated with many physical properties. In this paper some further relationships are shown, including surface area, base exchange capacity, total percentage of iron and titanium, and high-temperature mullitization. Surface area, base exchange capacity, and the total amount of iron and titanium in the clay increase as the degree of crystal perfection decreases.

A possible structure for kaolinite was first put forward by Pauling (1930) in a paper dealing generally with the structures of layer-type minerals, chlorites, micas, &c. He suggested that the structure consisted of a sheet of Si–O tetrahedra arranged in a hexagonal network with a superposed sheet of Al–(O,OH) octahedra, the two together forming a layer of composition Al2Si2O5(OH)4 (fig. 2). Ross and Kerr (1931), from a detailed microscopic study of the kaolin minerals, concluded that the symmetry of kaolinite is ‘probably monoclinic’. The first attempt at a detailed structure analysis was made by Gruner (1932a) from X-ray powder photographs. The reflections, some 40 altogether, were indexed on the basis of a monoclinic cell with a 5·14, b 8·90, c 14·51Å., β 100° 12′.

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.

A colloidal aluminosilicate complex with a given composition becomes a fixed deposit in a certain environment in the weathering crust on the earth's surface, as a non-dispersive isoelectric precipitate, according to the acidity of that environment., The writer proposes that its distribution in nature can be summarized, in a general manner, by "Isosials" or "Equal Silica-Alumina Molecular Ratio Lines"., It is controlled by meteorological factors and hence there is a regular harmony among different climatic zones, the fullest developed being a laterite profile in the tropics., A laterite profile, in the arrangement of its component minerals, resembles the profile of a low temperature hydrothermal alunite deposit., Although the alunitization is caused by the heat from the earth's interior, or is controlled by the energy of an entirely different source, the similarity is due to the fact that the elements of the chemical reactions, above and below the underground water table on the earth's surface, closely resemble each other., It is also quite natural that there is again a striking similarity between the stability fields of those minerals in the hydrothermal syntheses of silicates, as conducted by Noll and others, and the environments of the formation in the above two profiles in nature., In view of its position with regard to the "ISOSLALS" a bauxite is, no doubt, the product of an extreme weathering, hill tops or cliff edges on a level land and a tropical monsoon being the optimum for its formation., Stratigraphically, the bed of a redeposited laterite can be reckoned as an abnormal facies of a basal conglomerate., It is because the laterite is an end product of weathering on a level land., The lenticular rich ore bodies of the bando-ketsugan (aluminous shale) are channel deposits on a lake bottom, being comparable with the U, V and Cu bearing clay lenses in the "Red Beds" in the western US., The bando-ketsugan (aluminous shale) and the Koshitsu-nendo (flint clay) beds, are reworked laterite materials in the Upper Paleozoic age in N., China, S., Manchuria and Korea., They reach 20m in their aggregate thickness in most coal-fields, and are the largest of all known ore beds of kaolinite and aluminous hydroxide in the world., This is due to the fact that this region, in the Upper Paleozoic era, formed an extensive sedimentary basin of an epeirogenic type with the gentlest crustal movement in the world., In contrast, the Mesozoic era, in the same region, witnessed the formation of many local sedimentary basins of an orogenic type., The character of those crustal movements accounts for the distinct types of coal ash and the composition of clay colloids deposited in both basins., That is, the coal ash, in the sedimentary basin of an orogenic type, are characterised by the montmorillonite series or the clay minerals in the juvenile stage of evolution, while those in the sedimentary basin of an epeirogenic type, by the kaolinite series or those in the mature stage of evolution., Further, the laterite materials of the bando-ketsugan are clay minerals in the senile stege, or the ones which have the least chance both of formation and preservation in the region of an orogenic movement., The writer, in the present paper, proposes the term and concept of "Isosials" which, representing a regular arrangement of soil colloids in the generalized soil profile covering the Frigid and Tropical zones, point to the "evolution" of clays., He has also illustrated that the types of coal ashes, when represented by clay minerals in different stages of the evolution, reflect different types of crustal movements to which the coal basins are due.

In part I of this series physico-chemical studies on the fixation phenomenon of the cations adsorbed on kaolinite caused by drying were carried out and a new theory of the fixation of adsorbed cations, being quite different from any current theories which have been introduced so far by soil scientists, was advanced by the authors.In the present paper the fixation phenomenon of adsorbed cations such as Li+, Na+, K+ and Ca++ on halloysite surface caused by drying was studied. it was confirmed that the mechanism of the fixation for kaolinite may also be applicable to halloysite.

The clays appear under many widely different aspects, and from one point of view must be studied as rocks. There are rock-masses alike of clay and of serpentine, both the result of important metamorphic processes. The basis, however, of most—probably of all—clays appears to be a substance of definite composition and well-marked characters, as much entitled to specific mineral rank as allophane or serpentine, or perhaps opal. In this paper I propose to consider clay as a rock and as a mineral.

Tendo em vista um estudo genético da série Guamium, foram analisados três perfis de solo de Piracicaba, SP. A série Guamium é um Latossolo Vermelho Escuro orto, proveniente de um siltito do Grupo Tubarão, de origem glacial. Os perfis P1 e P2 apresentaram variações: a) nos teores de mica, os quais diminuem, da rocha para os horizontes superiores, de 28% a 2% no P1 e de 22% a 0% no P2; b) nos teores de caulinita, os quais aumentam, no mesmo sentido, de 54% a 87% no P1 e de 50% a 73% no P2; c) nos teores de gibbsita, os quais aumentam, no mesmo sentido, de 0% a C,6% no P1 e de 0% a 8,9% no P2; d) nos teores de alofana, os quais decrescem, no mesmo sentido, de 15% a 1,2% no P1 e de 22,5% a 14,0% no P2. O perfil P3 apresentou variação na composição mineralógica, em profundidade, não significativa, indício de que o seu material de origem foi previamente meteorizado e, ao ser transportado ao local que ocupa atualmente, foi homogenizado. Os perfis P1 e P2, ao contrário, provêm de um material de origem alterado in situ. Com base nos dados mineralógicos obtidos para os perfis P1 e P2 foi constatada a seguinte seqüência de meteorização: siltito -> caulinita e alofana -> gibbsita, que vem à ser a mesma encontrada na alteração de rochas básicas, rochas alcalinas, ardósia (de Brasília) e arenito Bauru. This paper presents results of studies on the genesis of three soil profiles, which has been classified as series Guamium. This is an Ortho Dark Latosol which has developed from a siltstone of the Tubarão Group (Carboniferous period). Samples studied are from Piracicaba, SP. Statistical analysis of the sand fraction were performed, as well as, quantitative mineralogical analysis of the clay fraction. According to the sorting coefficient data, the two profiles (Pt and P2) are poorer sorting than the third one (P3). Both profiles, P1 and P2, have similar mineralogical features. The mean contents of kaolinite and gibbsite of Ap to R horizons, decreased from 87 to 50% and from 89% to zero, respectively, while the mica and allophane contents increased from 0 to 28% and from 1.2 to 22.5%, respectively. The profile P3 almost did not present any variation in the mineralogical analysis on depth. The kaolinite content presented an average of 74.8% and the others minerals presented the following averages: gibbsite 6.8%; mica 0.6% and allophane 16.9%. According to both mineralogical analysis of the clay fraction and statistical analysis of the sand fraction, the profiles P1 and P2 are similar and belong to the series Guamium, while the profile P3 have different features and does not fit in that series. The following weathering sequence were found from the mineralogical data of the profiles P1 and P2: Siltstone -> Kaolinite and Allophane -> Gibbsite.

This paper deals with the shear strength characteristics of saturated, remoulded, montmorillonite and Kaolinite clays as affected by changes in soil structure. The changes in soil structure were made by changes in initial moulding water content, stress history and type of cation and its concentration in the electrolyte system. Throughout the investigation, isotropically consolidated undrained tests with pore water pressure measurements were conducted. The experimental results show a definite cohesion intercept even for saturated normally consolidated clays, under certain conditions. The modified effective stress concept, which takes into consideration the electrical attractive and repulsive forces appears to explain satisfactorily the strength mechanism. The qualitative analysis of the test data brings out the dire need for quantitative evaluation of electrical attractive and repulsive forces in order that a realistic determination of strength parameters could be made. The manifestation of components of shear resistance has also been discussed briefly.

In succession to the investigation on the crystallization of mullite needles in large feldspar particles this paper concerns on the microstructure of the bodies consisting of coarse feldspar grains embedded in kaolinite powder.Complicated Becke's lines were observed at the boundary between the molten feldspar grain and the matrix phase suggesting that there was diffusion between the two phases.The photomicrograph (photo 2) indicates that the molten feldspar showed the trend of approaching each other by forming the veins in the matrix, or by the deformation of the grains.During these processes the pores included in the grains joined together to become larger (photo 2, 3). At higher temperatures the reduction of viscosity made the reaction more and more rapid until the bubbles suddenly open. This may be a mechanism of the formation of bubbling in over-fired bodies.Feldspar grains locating next to cracks indicate that the molten mass pushed into the cracks through the veins by the pressure of expansion of feldspar with melting and pores in the grains.It was thus observed that the pores near the cracks are larger than ordinary size, suggesting that the bubbles in the molten feldspar had the potential power of further expansion puhsing out the matrix, changing the shape of the grains to promote the intrusion of molten feldspar through the veins.If the body was heated further after the cracks had closed the expanding gases found their way in the weak points to form large pores in the feldspar grains locating near the cracks. It is highly probable that a part of pores in porcelain bodies were formed in this way.The needle crystals came out earlier and far greater in number in feldspar melts being sandwiched in the crack.In a few specimens fired at as high as 1450°C it was observed that the needle crystals were concentrating at the surface of large bubbles showing that they were pushed back by expanding gases after the deposition of the crystals. It was also observed that the crystals were accumlating at the surface which was pushed back by expanding gases enclosed in the crack. This is the positive proof of the author's conclusion that the needle crystals in feldspar appears in the heating up period.Moreover, it was concluded that the deposition of the crystals in molten feldspar begins in the heating up period when the expansion of gases and the penetration of feldspar into the crack have just come to an end.

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.

Stephanite has been the subject of two important memoirs. Schröder examined minutely the crystals from Andreasbcrg ; Vrba has described fully the character of the stephanite from Przibram and other localities, and has given at the same time a summary of the observations of previous mineralogists, so that his memoir constitutes a monograph of the mineral. By neither of these observers, however, nor elsewhere, has it been stated that stephanite is hemimorphic, although it has been suspected of being possibly hemihedral. It is the object of the present paper to establish the hemimorphism of stephanite upon evidence similar to that which has been employed in the case of pyrargyrite.

Summary Several studies (e.g. Bolt et al., 1963; Beckett, 1964a) of the exchange equilibria between K and Ca on soil colloids or pure clay minerals have drawn attention to the presence of sites with different affinities for K. There is so far no evidence to indicate the location of sites with the highest affinity, though several workers (e.g. van Schouwenburg and Schuffelen, 1963) have assumed that they lie on the edge-faces of stacks of clay plates, or in the spaces between the expanded leaves of partially weathered stacks of clay plates. Earlier work has resolved the K: Ca exchange isotherms of soils and clays into a curved part at low values of aK/√aCa, attributed to exchange at sites with a high specific affinity for K, and an upper linear part commonly described by the Gapon equation and attributed to non-specific sites. The present work on soil clays and clay minerals shows that Na hexametaphosphate or changes in pH affect the curved but not the linear part; cetyl trimethyl ammonium bromide and changes in the amount or charge of exchangeable Al affect the linear but not the curved part of the isotherms. At low pH, the linear but not the curved part of the kaolinite isotherm obeys Schofield's Ratio Law. Grinding has more effect on the curved than on the linear part. So the specific sites are attributed to the edges or peripheral interstices of stacks of clay plates, and the non-specific sites to their planar surfaces. The specific sites take up K more slowly from solution than the non-specific sites. The isotherms of completely dispersed bentonites have no curved part. The specific sites are attributed to the wedge-shaped interstices opened between clay plates by weathering, from which exchange is diffusion-controlled. Added organic cations reduce the numbers of both kinds of site; peroxide treatment increases them. This paper confirms that the exchange sites with highest affinity for K are indeed associated with the edges, rather than the faces, of stacks of clay plates.

In the first part of this paper the formation processes of pure octahedral hydroxides are investigated. Conditions of synthesis of aluminum, magnesium, iron and mixed Al-Mg, Al-Ca, Al-Fe systems are successively reviewed. In every case crystal growth in deionized medium allows one to figure out genetic conditions. The second part deals with the conditions required for the development of the octahedral layer in the presence of silica, i.e. the clay mineral synthesis. Experimental conditions remain always as nearly as possible to those observed naturally. Trioctahedral minerals are rather easily obtained at ordinary temperature and pressure. The evolution of the magnesium-silica system is described. Synthesis of dioctahedral layer lattices, such as those of the kaolin minerals, appears more difficult to perform under the same conditions. Initial organization of the starting materials plays an important role in this case and procedures are described. Finally, interactions of octahedral and silica layers are studied. The study of infrared spectra in the 9–11μ region permits such observations. Characteristic changes in the spectral region of Si-O stretching allows one either to follow the octahedral destruction (by acid attack or dehydroxylation) or the octahedral layer formation in kaolinite synthesis.

In this paper, we have investigated on the packing characteristics of the clay bodies which are affected by the burning shrinkage in the course of the sintering proces from ordinary temperature up to the temperature of 1000°C.Such clay bodies contain absorbed humidity, crystallization water, carbonlike or organic matters, and these combustible matters are gastified in the process of burning, and consequently these bodies are contracted remarkably.The change of the packing arrangement of clay bodies is intricate and some observations were made to analyze these phenomenon.First we took up the Kaolinite clays containing “sericite” as the components, only poor packing densities, comparing to their large contraction, were obtained when they were exposed on the burning schdule.When, on the other hand, we took up the Kaolinite clays containing no “sericite” as the components, the resulted packing properties were dense.The samples containing known amounts of carbon powder (graphite powder used) as the combustible constituent, were also observed, and their packing densities fell significantly in the burning process, and there were intimate relations between these carbon contents (Combustible constituent) and loosening characteristics of the packing arrengements. Consequently, we may say (ex-emx) values1) for the clay bodies containing carbon were affected by the heating loss or contraction of the bodies and raw clay itself.

On the Mineralogical Composition of Swedish Quaternary Clays. The literature direetly deseribing Swedish Quaternary clays from a mineralogical point of view is very scanty. To some extent, supplementary data may be found in papers treating other clay problems and quite different geological questions, respectively. On the basis of such an incomplete material and some new data, the author gives a short account of the subject. As in Finland and Norway, illite appears to be the dominating clay mineral in Swedish Quaternary clays, both in Glacial and Post-Glacial types. Fur. thermore, kaolinite seems to occur. In western Seania (southernmost Sweden) montmorillonite minerals, derived from Triassic sediments, are probably to be found in Quaternary clays, while in eastern Scania kaolinite from Cretaceous deposits is supposed to play a greater role. The data available support the assumption by some earlier authors of the material of Quaternary clays of Fennoscandia consisting largely of Tertiary and, to s...

Recognition of the fact that clays exhibit both viscous and elastic response characteristics has led to the use of the theory of viscoelasticity for describing their mechanical behavior. This paper presents a brief outline of pertinent concepts from this theory to establish a framework for the presentation and interpretation of the experimental results. The experimental program was conducted on a water-washed Georgia kaolin at nominal moisture contents of 50%, 75%, and 100%, and included a series of oscillatory shear tests over a frequency range of two decades. These tests were performed on a Weissenberg Rheogoniometer with a cone-and-plate sample holder; this arrangement produces essentially homogeneous shear strains throughout the specimen.

The present paper deals with the micro-structure of a kaolin clay compacted in accordance with JIS *** A 1210. The methods used for investigation are the scanning electron microscopy using samples impregnated with polyethylene glycol, the X-ray diffraction, and the permeability test method. From this series of experiments, it is recognized that the micro-structure of the compacted kaolin clay mainly consists of block structures which are almost independent of the inner particle arrangement and are of the three-dimensional structure. The two-dimensional feature, therefore, varies depending upon the direction and position to be observed. It is also recognized that the parallelism as a soil mass increases more or less according to the molding moisture content as indicated by the results of X-ray analysis and fcoS2 from the Kozeny-Carman equation, and the change of this parallelism may be caused not by the change of each particle arrangement but by flattening and/or deforming of block structures.

Beginning with the work of Ladd in 1898, much has been written about the kaolins of the Southeast, with maximum coverage on the deposits of greatest economic value. Early studies were, of necessity, general in nature but also contain excellent detailed descriptions. In the past 15 years increased demands for kaolins to meet specific requirements have resulted in a large amount of detailed research, much of it unpublished. This paper attempts to review the available information placing emphasis upon the geologic and mineralogical data and the interpretation thereof with respect to the occurrence, detailed character and variability, and probable origin of the clay deposits. The commercial deposits of kaolin clay discussed herein lie throughout the sands of the Upper Cretaceous Tuscaloosa formation and are localized in a narrow belt along the southeast edge of the “fall line” from Macon, Georgia, to Aiken, South Carolina. The kaolin lenses are irregular in shape, size and purity, ranging from a few feet to a mile in length, and up to 50 ft in thickness. Variability within the lenses is a function of (1) the concentration and localization of non-clay materials (quartz, mica, gibbsite, pyrite, lignite; Fe2O3, TiO2, MnO), (2) the montmorillonite content, (3) the particle size and X-ray crystallinity of the kaolinite, and (4) the texture of the clay aggregate. These mineralogical, chemical and textural variables are not homogeneously distributed but reveal and help to explain differences between samples, layers, pits and the important hard and soft clay types of the region.

The relationships between the shapes of kaolinite and dickite differential lhermal curves are described. The slope ratios of dickite are distinctly greater than those of kaolinite of equivalent particle size for the endothermic peak at about 550~ and the same effect is observed for the exothermic peak at about 980~ especially in diluted samples. The packing density of dickite does not differ markedly from that of kaolinite and the curve obtained for weight vs. area of the endothermic peak is in agreement with this. The dickite samples, however, give slightly lower areas than those of kaolinite, an effect that is dependent on the shape of the particles. The exothermic peak is shown to be influenced considerably in shape and size by thermal gradients. INTRODUCTION Although considerable research has been carried out on the less well-ordered kandites, not so much attention has been paid to dickite and nacrite, especially as regards the m a t h e m a t i c a l relationships and shapes of the curves resulting from differential thermal analysis. In view of the restricted natural occurrence of these members of the group, the smaller amount of attention is not surprising. In this paper comparison is made between dickite and kaolinite and the relative shapes of the curves are utilised to gain an insight into the actual mechanism of the dehydroxylation reactions occurring on heating. EXPERIMENTAL The apparatus used had a temperature rise of 10~ nickel block and cover, chromel-alumel therrnocouples, and recording was by means of electronic recorders. The samples investigated were those used as standard clay samples by Kerr 0951) and were as follows, the number in brackets referring to the A.P.I. number: dickite, on U.S.550, near Red Mountain Pass, south of Ouray, Colorado, U.S.A. (No. 14); dickite, Bull Valley, 40 miles north-west of St. George, Washington Co., Utah, U.S.A. (No. 16); kaolinite, from Twin Knobs, Murfreesboro, Pike Co., Arkansas, U.S.A. 17 18 R. J. W. McLAUGHLIN (No. 1); kaolinite, from O'Neal pit 8.8 miles south-east Macon railway station, Georgia, U.S.A. (No. 4). The 2-20/z equivalent spherical diameter (e.s.d.) fraction was separated from the samples by centrifugal means, this fraction comprising almost the entire sample in the case of the dickite samples. X-ray examination and chemical analysis of these fractions revealed no foreign minerals and f rom the figures for the latter (Table 1) it will be seen that chemically the specimens are almost identical, so that any differences in behaviour must be largely due to morphological effects. The general chemical relationships between these and other kandites have been reported elsewhere (McLaughlin, 1959). TABLE 1--Chemical analyses of 2-20~ e.s.d, fraction of various kandites (in .per cent.)

This paper discusses petrographic and mineralogic features of kaolinite and associated minerals from a certain kaolin deposit near Spokane, Wash. Here the kaolin occurs in dikes, veinlets cutting a sandy material, and has field relations and mineral associations that are not in harmony with the usual conception of residual deposits due to weathering. The evidence points strongly to endomorphic action or perhaps even direct primary origin from highly aqueous magmatic solutions.

x-ray diffraction traces were made of oriented aggregates of artificial binary mixtures containing approximately equal, weighed amounts of samples of illite, montmorillonite, mixed-layered combinations of illite and montmorillonite, and of kaolinite samples having different degrees of crystallinity. Measurements most suitable for quantitative purposes were obtained from the 7 a kaolinite peaks and from the 10 a peaks of illite and collapsed montmorillonite and collapsed mixed-layer clay. In this paper the sum of five height measurements at half-degree intervals across the peak are considered to be a measure of the area of the peak. Fireclay-type kaolinites gave 7 a peak areas about equal to the area of the 10 a peak of an equal amount of illite, montmorillonite, or mixed-layer clay, whereas well-crystallized kaolinites gave 7 a peak areas generally about twice that of the 10 a peak of an equal weight of the illite-montmorillonite minerals. Kaolinite samples having intermediate degrees of crystallinity gave 7 a/10 a peak area ratios intermediate between 1: 1 and 2: 1. The shape of the 7 a kaolinite peak was used to evaluate the crystallinity of the kaolinite. x-ray diffraction characteristics of the chlorite minerals from the different groups of sedimentary rocks studied vary considerably, and no uniform method has been found for their evaluation.

This paper documents the first report of flint clay in Mexico, located at Estola, Guerrero, 199 km south of Mexico City, on Mexico Highway 95. It is the first report (known to the writers) of flint clay formed by hydrothermal alteration. It describes the in-situ alteration of a calcareous, silty shale to flint clay (well-ordered kaolinite).

Active kaolinization of middle Tertiary obsidian and rhyolitic breccia in the San Andres range is effected by sulfurous hot waters and hydrous vapors emitted as springs, fumaroles, and geysers. The alteration preserves original rock textures and forms conspicuous aureoles around the hydrothermal vents, which shift about with slumping of the saturated clay. Systematic exploration by 87 test pits with maximum depth of 45 ft permitted inspection of the kaolin in place, and furnished bulk samples for laboratory work. Besides kaolinite, the clay contains unevenly distributed cristobalite and alunite, and traces of mercury. The natural brightness of the pure kaolinite approaches 90 if unstained by weathering, but little of it is pure. The yield of paper-coating fraction is small, and the composition and behavior in slurries are nonuniform. Most of the kaolinized material in the hydrothermal deposits is soft. Some, however, is hard and rock-like. Similar material occurs in clastic sediments of late Tertiary age, suggesting that the hydrothermal activity began at least as early as the Pliocene.

This paper deals with a series of soil-clay minerals which have a widespread distribution in the north-east of Scotland. The original member is a biotite-like mica which breaks down readily in the soil into (i) a vermiculite or (ii) a montmorillonite, depending on the soil-forming conditions operating. Apart from this 'clay biotite' and its decomposition products, the main crystalline constituents of the Scottish soil-clays are a member of the kaolinite group and illite (' clay muscovite'). Iron and aluminium oxides are present in all the clays in the amorphous condition, but crystalline varieties are scarce. The distribution of the minerals and their relationship to the various soft-forming factors will form the subject of a separate communication; here, the nature of the clay minerals and their interrelationships are considered.

This paper deals with the one-dimensional volume change behavior of kaolinite, momtmorillanite and black cotton soil, when soaked in the partly saturated state. These clays were compacted in a partly saturated state to different densities with different initial moisture contents in oedometer rings loaded to different pressures ranging from 0.0625 to 8.0 tons/sq.ft and then soaked with distilled water at these pressures. Futher, consolidation was then carried out on these soaked samples, in the conventional manner. The results were analysed in the light of the modified effective stress concept together with the physical mechanisms involved. The results obtained clearly indicate that the volume change behavior of these clays during soaking is controlled basically by two mechanisms which are governed by the modified effective stress concept which takes into consideration the electrical, attractive and repulsive forces at particle level. In mechanism I, the volume change behavior is controlled by the shearing resistance at interparticle level and in mechanism II, by the long range electrical repulsive forces. Although these effects operate simultaneously, mechanism I parimarily controls non-expanding clays like kaolinite, and mechanism II the expanding lattice type of clays like Montmorillonite.

THE OBJECTIVES OF THIS PAPER IS TO PRESENT FLOW SHEETS FOR A SYSTEM OF QUANTITATIVE MINERALOGICAL ANALYSIS OF CLAYS OF SOILS AND SEDIMENTS AND TO SHOW REPRESENTATIVE RESULTS. SELECTIVE DISSOLUTION ANALYSIS YIELDS THE QUARTZ AND FELDSPAR CONTENTS /0 TO 63 PERCENT/ AND DIFFERENTIATES FELDSPAR K FROM MICA K. THE NAOH-THERMAL SYSTEM OF SELECTIVE DISSOLUTION YIELDS THE ALLOPHANE PLUS GIBBSITE, KAOLINITE PLUS HALLOYSITE, AND DICKITE CONTENTS /0 TO 84 PERCENT FOR THE SEDIMENTS 1 TO 25 PERCENT FOR SOIL CLAYS/ MICA CONTENTS /0 TO 92 PERCENT FOR THE ROCK SPECIMENS, 7 TO 43 PERCENT FOR SOIL CLAYS/ ARE DETERMINED BY NONFELDSPATHIC K /AND NA/ VERMICULITE CONTENTS /1 TO 97 PERCENT OF SPECIMENS, 3 TO 21 PERCENT FOR SOIL CLAYS/ ARE MEASURED BY BLOCKING OF INTERLAYER CEC BY DRYING AT 110 DEGREES C WHILE K SATURATED AND REPLACING WITH AMMONIUM CHLORIDE. MONTMORILLONITE /AND PALYGORSKITE/ CONTENTS /0 TO 85 PERCENT OF SPECIMENS, 3 TO 36 PERCENT OF SOIL CLAYS/ ARE DETERMINED BY THE CEC NOT BLOCKED BY THE K AND AMMONIA SEQUENCE FOR VERMICULITE. CHLORITE CONTENTS /0 TO 85 PERCENT FOR SPECIMENS, 0 TO 37 PERCENT FOR SOIL CLAYS/ ARE DETERMINED BY THERMAL GRAVIMETRIC ANALYSIS, AFTER ALLOCATION OF OH WATER LOST BETWEEN 300 AND 950 DEGREES C TO OTHER HYDROUS MINERALS DETERMINED. THE BEST EVIDENCE OF THE ACCURACY OF THE SYSTEM OF ANALYSIS LIES IN THE CONSISTENT TOTAL RECOVERY OF 24 STANDARD MINERAL SAMPLES AVERAGING 100.4 PLUS OR MINUS 1.3 /PLUS OR MINUS STANDARD ERROR OF MEANS/ AND OF 22 SOIL CLAY SAMPLES AVERAGING 99.5 PLUS OR MINUS 0.8. THE DIFFERENT CONSTITUENTS WERE PRESENT IN WIDELY DIFFERENT PROPORTIONS IN THE VARIOUS SAMPLES, AND WERE DETERMINED BY INDEPENDENT METHODS. THE COMPLEMENTARY TOTAL OF NEAR 100 PERCENT /MAXIMUM RANGE 95 TO 105 PERCENT FOR SPECIMENS, 95 TO 103 PERCENT FOR SOIL CLAYS/ FOR THE ANALYSES IS A SIGNIFICANT MEASURE OF THE SPECIFICITY OF THE SEVERAL DETERMINATIONS. /AUTHOR/

THE nature of the particle–particle interactions in clay suspensions is of great technological importance since these interactions determine the flow properties of suspensions used in, for example, ceramic manufacture and paper making, and as oil drilling fluids. They also influence profoundly the structure and behaviour of soils. Clay particles are of a plate-like morphology and thus exhibit two types of surface, the edges and the basal faces. Consequently, a variety of different types of particle–particle interaction are possible in aqueous clay suspensions1,2. For example, structures consisting of individual particles coagulated in an edge–face or an edge–edge arrangement have been proposed as well as face–face (or ‘card–pack’) aggregates which may themselves be coagulated in edge–face or edge–edge modes2.

From 1945 to 1949 clay-mineral studies in Belgium were connected with the Comite Belge pour l’Etude des Argiles, In 1947 this group organized the C. I. P. E. A., which in turn helped to form active national groups of clay workers. Clay-mineral research is now pursued in five laboratories in Belgium. Projects in Brussels include industrial problems, study of reactions of silicates and the oxides of Al, Ca, and Mg; quantitative determinations by x-ray spectrometry; and the use of a differential thermobalance and electron microscopy. Basic clay-mineral problems involving agriculture are being studied at Heverlee, where investigations include studies of fixation of iron on kaolinites and examination of the topography of kaolinite minerals attacked by different reagents. A group at Tervuren has been concerned with formation, deferrization, and determination of oxides by D. T. A. The Laboratoire National des Silicates at Mons is investigating creep phenomena in refractories. The activities of the Ghent group are described in a separate paper.

Among the factors that influence the amount of water held in clayey sediments under overburden pressures between 0 and about 50 kg per cm are particle size, clay minerals, exchangeable cations, and interstitial-electrolyte concentration. The amount of water held in clayey sediments varies inversely with particle size through a wide range of pressures and chemical conditions. The influence of different clay minerals on water content is related mainly to their particle size. The influences of exchangeable cations and electrolyte concentration also vary with particle size: in fine-grained clays (montmorillonite, for example), water content varies inversely with the valence of exchangeable cations and the concentration of monovalent electrolyte; in coarse-grained clays (kaolinite, for example), water content varies directly with the cation valence and the electrolyte concentration. Under overburden pressures greater than about 50 kg per em ll' the major influences on the water content of clayey sediments seem to be particle size, clay minerals, and temperature. As temperature increases, less pressure is needed to compact the clay. Variations in exchangeable cations and in electrolyte concentration do not seem to influence the water content under higher pressures, but they do affect the clay-particle fabric. Although preferred and turbostratic orientations of claymineral particles can be produced by compressing clays in the laboratory, there is little evidence to show that they are formed readily during natural compaction. Experimental evidence suggests that preferred orientation of particles, normal to overburden pressures, would be most likely to form in sediments that have large clay-mineral particles, low concentration and low acidity of interstitial electrolyte, and low valence of exchangeable cations. The formation of a preferred orientation also seems to be favored by the presence of organic material and the existence of a partly oriented fabric at the onset of compaction. The formation of a turbostratic fabric (particles oriented in domains which are oriented at random with respect to other domains) instead of generally preferred orientation might be favored by high electrolyte concentration and high