Aluminous clay minerals such as pyrophyllite, dickite, sudoite, tosudite, rectorite, and sericite were found in a drillhole which was sunk near the Kamikita mine, Aomori Prefecture, Japan. These minerals display a zonal arrangement as follows: pyrophyllite (±diaspore±dickite)→sudoite (±sericite)→tosudite (±sudoite±rectorite)→rectorite (±tosudite±sudoite) from the central part of alteration envelopes to the marginal part in the Miocene Wadagawa formation.
The structure formula of sudoite was calculated as (Mg_1.76Al_2.88Fe²⁺_0.16Mn_0.01Ti_0.04Na_0.06K_0.01Ca_0.01) _4.93 (Si_3.26Al_0.74) O₁₀ (OH) ₈from electron microprobe analysis, though it contains a small amount of expandable layer. The material has a II_b polytype and 1.507 Å of d (060) value. Tosudite intergrew intimately with sudoite. Two kinds of interstratified mica/smectites (M/S) containing 30 and 40% of expandable layers (%Sm) were identified; they showed large intergrain chemical variation. The interlayer cation composition of rectorite is variable with respect to different depths of a drillhole and to different drillholes. K-rectorite occurs interrelatedly with M/S having 30 and 40%Sm, pyrophyllite, sericite, and sudoite. The spatial and chemical relations of these minerals indicated that the reaction series, pyrophyllite→M/S (30-40%Sm) +pyrophyllite→K-rectorite±sericite, proceeded from pyrophyllite zone to the out-ward as the result of increase in activities of Na, Ca, and K in hydrothermal solution. At the same time, elemental distribution reaction took place with the formation of the above minerals; Fe, Mg, and K were selectively accomodated in sericite and Na, Ca, and Al were in rectorite.

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A powdered sample of natural sepiolite from Turkey was sintered by a hydrothermal hot-pressing technique. Density and compressive strength of the sintered samples were increased with the amount of water added and the reaction temperature. However, excess water did not increase them notably. Fibrous crystals of the sepiolite wereeffectively rearranged and sintered at temperatures above 280°C. The sintered samples were not crumbled in boiling water. Profiles of X-ray powder diffraction were not significantly changed by this treatment. Values of specific surface area of the sintered samples were more than 150m²/g, which suggested that the tunnel structure in the sepiolite was not modified by this treatment.

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The present paper reviews the interaction of synthetic and natural iron oxides withclay surfaces in terms of the charge characteristics of iron and clay minerals, and therole of iron oxide in the clay soil behaviour. The association of iron oxide particleswith clay surfaces in the synthesized iron oxide-clay complexes was due to coulombicattraction. For natural clay soils the specific adsorption of anions on iron oxides affectedthe association between iron oxides and clay minerals. Addition and extraction of ironhydroxides and oxides in clays indicated that iron minerals contribute to a decreaseof sensitivity and an increase of Bingham yield stress.

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Montmorillonite-acrylamide intercalation compounds were prepared by treating sodium montmorillonite with acrylamide aqueous solutions, the concentrations of which were varied from 4% to 20%. The basal spacings of the compounds prepared from 4% and 20% acrylamide aqueous solutions were ca. 15 Å and 20 Å, respectively. These values suggested that acrylamide was intercalated as monomolecular and bimolecular arrangements in the interlayer space of montmorillonite with the molecular plane perpendicular to the silicate sheet. After the removal of excess acrylamide by washing with nonpolar organic solvents, the intercalated acrylamide was polymerized to form montmorillonite-polyacrylamide intercalation compounds. These compounds absorbed more water than raw sodium montmorillonite.

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Nickel aluminum double hydroxides, Ni_1-xAl_x (OH) ₂ (CO₃) _x/2·mH₂O, were prepared from a hexaamminenickel (II) complex solution by the addition of mixed solutions of aluminum nitrate and sodium hydroxide. The crystallinity of the products was better than that of the double hydroxides prepared by a conventional coprecipitation method. Based on the relationship between the layer spacing and the atomic fraction Al/(Al + Ni) in the products [=R (pro)], the range for the formation of the single phase products was determined to be 0.19≤R (pro)≤0.33. In this range the layer spacing diminished with the increase in R (pro). IR and DTA results also indicated the variation in the layer charge caused by the aluminum substitution. The anion exchange capacity was 1.5-2.6 meq/g within the solid solution range. The thermal behavior of the products was also investigated.

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