Imogolite was studied by the scanning electron microscope. Imogolite which examined was separated from Kurayoshi pumice beds. The samples were dried successively in the sealed vessel at critical point of CO₂. This drying method exceeds in preservation of natural surface of imogolite than that of air-drying.
The form of imogolite was observed as fibres-like threads. The threads were curled and entangled forming nets which were piled up one above the other. The diameter of these threads ranged from 0.03 to 0.06 μm.

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In order to investigate the genesis of stevensite and “hydrated talc” experimentally, naturally occurring wollastonite and pectolite were treated hydrothermally with MgCl₂ solution for temperatures ranging from 100°C to 200°C. The products were examined by means of X-ray diffraction, thermal analysis, infrared absorption spectroscopy and electron microscopy.
Both wollastonite and pectolite alter to “hydrated talc” +chrysotile (200°C-350°C) and then talc+chrysotile (≥400°C). Below 150°C is formed the poorly crystallized silicate having a trioctahedral layer structure. The formation of stevensite can not be recognized under the present experimental conditions.
Some considerations are made on the mechanism of the conversion of wollastonite and pectolite.

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The adsorption of N₂, CO₂, CH₄, C₂H₆ and C₃H₈ in cation exchanged clinoptilolite was examined. Clinoptilolite tuff from Futatsui, Akita Pref., was used as a starting material, from which Na-, K-, Ca-and NH₄-clinoptilolite were prepared by cation exchange treatment.
Na-clinoptilolite adsorbs considerable amount of small molecules such as N₂ and CO₂ slowly, whereas it is able to adsorb a small amount of large molecules such as CH₄, C₂H₅ and C₃H₈rapidly. This result indicates that Na-clinoptilolite has two kinds of voids with different opening size. The apparent diameter of small aperture seems to be less than 3.7Å and that of large one more than 4.3Å. It is estimated that specific surface area of the smaller void accounts for nearly 2/3 of the whole surface area.
K-clinoptilolite adsorbs a large amount of CH₄ and C₂H₆ very slowly, and NH₄-clinoptilolite is able to adsorb them rapidly. These results indicate that the apparent diameter of the small pore is enlarged from 3.7Å to 3.8Å depending on cation exchange.
⁺Studies on Utilization of Zeolite Tuff (V)

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