Large amounts of illite/montmorillonite mixed layer minerals occur in Miocene tuffaceous sediments in Waga-Omono district in Akita Prefecture, Northern Japan. It was clarified by mineralogical and chemical examinations of subsurface samples obtained from drilling cores that authigenic minerals of hydrothermal origin are arranged zonally around a Cu-Pb-Zn deposit. The illite/montmorillonite minerals are distributed in the intermediate position between the sericite-chlorite zone and the montmorillonite-zeolites zone.
The mineralogical properties of the illite/montmorillonite minerals change successively with the change in the content of expandable layer. Judging from x-ray patterns, the interstratification of the two minerals may change from random when the content of expandable layer exceeds 60%, to ordered when it is of 25-40% and less than 15%.
The chemical composition of the mixed layer mineral varies systematically in concord with the variation in the content of expandable layer. In the course of the transformation of montmorillonite to illite through their interstratification, Mg is expelled from the octahedral layer, while Al is added to the tetrahedral layer of the minerals.
In the studied area, the above transformation has occurred in the range of about 100 meters. According to Eberl and Hower (1976), the geothermal gradient at the time was estimated to be 20-30°C/100m.

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Effects of adsorbed ions on the viscosity of dilute allophane and imogolite clay suspensions were studied. The specific viscosity of allophane and imogolite which have the net positive charge depended on the anion species used for saturation but not on the cation species. On the contrary, the specific viscosity of allophane with the net negative charge did not depend on the anion species.
Effects of anions on the viscosity of allophane and imogolite with the net positive charge were inferred to be due to their effect on the total volume of particles in the suspension. The increase in the total volume of particles was caused by the increase in the amount of hydration water for the clays saturated with monovalent Cl^- and NO₃^- and by the increase in the amount of enmeshed water for the clays saturated with divalent SO₄^2-.

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Examination of asbestos fibers by analytical electron microscope enables to distinguish fiber types by morphological, structural and chemical characteristics. An attempt was made to use the ternary diagram of system MgO-total iron+MnO-CaO+Al₂O₃+Na₂O+K₂O, for the characterization and identification of asbestos types. The particulate materials present in lungs have been investigated. The results of energy dispersive X-ray analysis for mineral compositions of these particulate materials are comparable to those obtained by X-ray diffraction study on the lung dusts extracted from the same lung tissues.

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Changes in the pore structure of kaolin mineral due to dealumination by treating with sulfuric acid were studied. From the nitrogen adsorption-desorption isotherm, pore size distribution, and external and internal surface areas were measured. The mechanism of dealumination from kaolin mineral was discussed.

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To understand the pore structure and the surface properties of the dealuminated kaolin mineral, adsorption studies of ammonia and benzene were made, and the distributions of acid strength of these samples were measured by using an amine-titration method.
Isomerization of 1-butene was chosen as the test reaction. The products distributions were measured and the characteristics of acid site of the dealuminated kaolin mineral were discussed.

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