The estimation method of kaolin minerals with the DTG peak near 500°C and the ignition loss of the clay fraction was proposed, and was effective for estimating the minerals in soils by the following reasons. The content of kaolin minerals obtained here was almost proportional to their ratio in the artificial mixture with montmorillonite although their contents were slightly higher than the value expected from the mixed ratio, and the linearity of the XRD graph was inferior to that of DTG. The DTG peak of kaolin minerals was separated almost completely from the neighboring peaks originated in montmorillonite and chlorite. This separation was considerably difficult in the TG curve.
Kaolin minerals in six Amazon soils were estimated by this method, and their contents were from 230 to 820 g·kg^-1.

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The aspect ratios of rod-like and discoidal particles including six clay and two amphibole asbestos materials were evaluated by comparing the particle size distribution data derived from sedimentation measurements with those by a laser scattering method, following the techniques described by Jennings and Parslow (1988). The evaluated values were compared with the geometrical length ratios of individual particles which were determined independently by an image analysis made on transmission electron micrographs.
In the rod-like particles of halloysite and amosite, whose shapes are characterized by the two major and minor lengths of the particle, the aspect ratios evaluated from the two instrumental measurements were nearly consistent with the geometrical length ratios by the imaging method, though the consistency was not good exceptionally in crocidolite. On the other hand, the discoidal particles studied here showed significant deviations between the two ratio values. Their shapes are actually characterized by the three parameters of particle, i.e., the length, the width, and the thickness; the ratios of these three parameters all contribute to the divergence between the different particle size measuring instruments. Taking a geometrical mean of the length/thickness, the width/thickness, and the length/width ratios was satisfactorily consistent with the aspect ratio value evaluated from the instrumental measurements. It is conclusive that the divergence observed between the different particle size distribution measuring instruments is sensitive to the aspect ratio of the particle, as shown by Jennings and Parslow (1988). Nevertheless, if the particles have appreciably three different parameters required to characterize the geometries, the aspect ratio evaluated by instrumental measurements is related to all of the geometrical length ratios of individual particles.

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Species P has similar X-ray powder patterns to those for gismondine and phillipsite. As for polycrystalline zeolitic materials with low crystallinity, such as so called species P, the diffraction peaks from the different planes, whose d-spacing are closely resemble, overlap with each other, and show only a few broad lines. The structural differences between phillipsite and gismondine are discussed based on the reported space groups and X-ray powder data, and the sine qua non for the X-ray powder data for phillipsite was deduced.

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Intercalation reactions of water and ethylene glycol into the interlayer space of copper (II) montmorillonite have been investigated by means of X-ray diffraction, thermogravimetry, and infrared and electron paramagnetic resonance spectroscopies. Both of the guest molecules form a single-layer, a double-layer and a triple-layer (only with water) complexes between the silicate layers. In the single-layer complex copper (II) ions are co-ordinated octahedrally to six oxygen atoms, two of them being the silicate oxygen atoms and the others guest molecules co-ordinated to the cation, and the symmetry axis is perpendicular to the silicate layers. In the doublelayer complex copper (II) ions are in an axially elongated tetragonal field of six coordinated molecules with the symmetry axis inclined with respect to the layer surfaces at an angle near 45°. If there layers of water molecules occupy the interlayer region, the hydrated copper (II) ions are free in tumbling motion to almost the same extent as that in an aqueous solution. The interlayer copper (II) ions complexed with water and ethylene glycol were irreversibly hydrolyzed in contact with air.

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Montmorillonite was treated with a small amount of aliphatic alkyltrialkoxysilanes with different lengths of alkyl chains in dry air. The alkyltrialkoxysilane molecules were chemically bonded on to the edge surface of the silicate layers of montmorillonite. Rheological behavior of the aqueous suspensions of the products was investigated as a function of the number of carbon atoms in the alkyl chain. The viscosity of the suspensions considerably increased with the increase of the number of carbon atoms in the alkyl chain and the type of flow changed to a typical Bingham flow, whereas the original montmorillonite suspension exhibited a pseudoplastic or socalled shear-thinning flow. The Robinson's viscosity equation and the intrinsic viscosity model of an oblate ellipsoid given by Kuhn and Kuhn (Güven, 1992) were applied to the viscosity data of the aqueous suspensions for the explanation of the particle characteristics of montmorillonite treated with n-hexyltrimethoxysilane. An appreciable increase of the intrinsic viscosity of the montmorillonite treated with n-hexyltrimethoxysilane suggested the formation of a lamellar structure of developed edge-to-edge arrangement of particles, due to the hydrophobic bonding of the alkyl chains on the edge surface. The product is expected to be useful industrially as a rheology-controlling agent for various aqueous fluid products.

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Molecularly-resolved surface images of both octahedral and tetrahedral sheets of kaolinite have been obtained by atomic force microscope (AFM) observation of pressed kaolinite powder in air. Tetrahedral-sheet images were frequently observed with molecular-scale resolution. Another type of reproducible images with 0.3-nm spacing was also obtained and interpreted as a sheet of hydroxyl groups on the octahedral sheet.

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