Clay minerals obtained from the weathering product of Ohya-ishi were examined by high resolution electron microscopy and selected area electron diffraction. Some mica crystals showed a unique morphology, They were very thin along the b-axis compared with c-axis. A high resolution electron micrograph showed a microstructure reflecting the arrangement of the tetrahedra in the unit layers of mica. Montmorillonite flakes showed a crossed lattice image of 4.5 Å spacing. A local ordering of unit layers in montmorillonite flakes was discussed.

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The kaolin deposits of the Seta mine, Hokkaido were formed by hydrothermal kaolinization of tuffaceous rocks. The kaolin of the Taisei-1 deposit replacing fine-grained rhyolitic tuff is of the highest quality, composed of about 60 percent kaolinite, 30-40 percent quartz and about 5 percent pyrite. Kaolinite may be classified into two types, A and B, by slight differences in crystallinity ; A is a well crystallized type with a triclinic cell, while B is a more disordered type, probably a “b-axis disordered kaolinite”. Kaolinite in the peripheral and basal parts of the deposit is of type A usualy accompanied by a minor amount of alunite, whereas kaolinite in the central part is mainly of type B. Micas are absent in this deposit, except for a small amount of a mixedlayer mineral of mica-montmorillonite. Mineral assemblages, represented by quartz-kaolinite-alunite in the fine-grained tuff and kaolinite-quartzmontmorillonite in propylite, show that the alteration took place at high activity of H⁺ relative to activities of metal cations.

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A chemical model for the structure of the double layer in the presence of organic ions and molecules in the vicinity of clay surfaces is postulated. The validity of this model is examined in the light of known literature on the interaction between clay minerals and organic compounds. The probability of the penetration of organic ions and molecules into the inner Helmholtz layer is discussed.
The effect of migrating water on the migration of hydrophilic and hydrophobic organic compounds through a rock is discussed. The rate of migration of organic compounds depends on their chemical nature as well as the nature of the rock. From the model on the stability of the double layer it may be concluded that amphipathic molecules (soaps) are carried with migrating water from pores where their surface density is low to pores where their surface density is high. There is a probability of a complete saturation of several of the pores with organic ions or polar molecules. Such a pore is defined as an “organo-pore” and is shown to be hydrocarbon permeable. Organo-pores may become the paths for primary migration of hydrocarbon in the argillaceous source rock.

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Iron-sepiolite occurs in a dolomite deposit of the Kasuga mine, Gifu Prefecture, Japan. This sepiolite shows a dark brown colour on newly exposed surfaces, which, however, easily turns to brown when exposed to the air. It is pleochroic with brown to yellowish brown, and the refractive indices α=1. 508 and γ=1. 525, which are higher than those of magnesium-sepiolite. The lattice parameters of iron-sepiolite are a₀=13.74Å, b₀=26.97Å and c₀=5.28Å. The X-ray powder pattern consists of well-defined peaks. The thermogravimetric curve of iron-sepiolite shows a continuous weight loss with the removal of zeolitic water and of hydroxyl groups leading to formation of a completely dehydrated phase. The peaks on the differential thermal analysis and the derivative thermogravimetric curves due to the removal of the bound water and dehydroxylation are extremely weak. The weight loss of iron-sepiolite resulted from the removal of both zeolitic water and bound water is close to that of magnesium-sepiolite, whereas the weight loss due to dehydroxylation is smaller in iron-sepiolite than magnesium-sepiolite. This is probably due to secondary oxidation of iron in the former. A reasonable structural formula of iron-sepiolite was obtained by converting all ferric iron to ferrous iron.

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Electrophoretic mobility of binary mixtures of imogolite and montmorillonite, kaolinite, hydrated halloysite and allophane was measured using a microelectrophoresis technique.
In acidic media, the negative electrophoretic mobility of the crystalline clays decreased to zero by the addition of imogolite with the positive electrophoretic mobility, and these two oppositely charged clays were flocculated. Montmorillonite required a larger amount of imogolite to complete flocculation than the 1: 1 type clays. When the imogolite content exceeded a neutralization point, the mixtures dispersed in the acidic media and they showed a positive electrophoretic mobility, where imogolite behaved as a protective agent. This effect was more marked for the mixtures containing the 1: 1 type clays than montmorillonite. The allophane-imogolite mixture showed, however, an electrophoretic mobility similar to that of allophane itself.
In alkaline media, the negative electrophoretic mobility of allophane and crystalline clays was decreased by the addition of imogolite. This decrease was more marked when imogolite was subject to the ultrasonic treatment for a longer time. The flocculation of other clay minerals in alkaline media by imogolite appeared to relate with the network formation of imogolite.

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Particle association between imogolite and some other clay minerals in aqueous suspension was investigated by electron microscopy using a freeze etching technique. Electron micrographs of the mixtures of montmorillonite-imogolite and allophane-imogolite in slightly acidic media revealed the association between imogolite and montmorillonite or allophane.The fine morphological feature of kaolinite-imogolite mixtures suggests that imogolite associates with kaolinite in acidic and alkaline media.The fine morphological features of the mixtures of imogolite and other clay minerals are discussed in relation to their electrophoretic behavior reported in the preceding paper.

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A nickeliferous fuchsite occurs in the Setogawa group, Shizuoka Prefecture in association with quartz, magnesite and chromite. The fuchsite contains 5.49 percent Cr₂O₃ and 2.00 percent NiO, and consists of only 1M polytype with the following lattice parameters: a=5. 275 (5)Å, b=9.045 (5)Å, c=10. 291 (5)Å and β=101.80 (10)°.

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