Ohya-ishi is Miocene tuff breccia occurring in Ohya district, Utsunomiya, Tochigi Prefecture, Japan. The matrix of the Ohya-ishis mainly composed of clinoptilolite, a kind of zeolite. It also contains many kinds of fragments, among which so-called “miso” is the most conspicuous. This is composed of intimate mixture of iron-rich saponite and iron-poor montmorillonite-beidellite.
Physical properties of powders of Ohya-ishi, miso and heated miso were investigated by the DTA method, etc. Their adsorption capacity was determined by methylene blue and ammoniacal nitrogen, and also relations between the adsorption capacity and composition of the contained minerals were investigated by the X-ray powder diffraction method.
As a results, methylene blue is much more adsorbed by miso than by the powder of Ohya-ishi, and ammoniacal nitrogen is more adsorbed by the powder of Ohya-ishi than miso. It seems that the clay minerals contained in the powder of Ohya-ishi and miso is mixture of montmorillonite and iron-saponite, and since miso contains more iron, it seems that miso contains more iron-saponite. After heating miso, adsorption of both methylene blue and ammoniacal nitrogen is reduced. Both powder of Ohya-ishi and miso have a higher decoloration of an aqueous methylene blue solution and can be used well as a commercial adsorbent.

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Four kinds of regularly interstratified 25Å minerals, paragonite-beidellite, Ca, Sr and Ba brittle mica-beidellite, were purely synthesized and examined mineralogically. These specimens show similar characteristics to rectorite (regularly interstratified mica-smectite) on X-ray diffractometry, thermal analyses and electron microscopy. Basal spacings of them depend on ionic radii of interlayer cations of non-expansible layers. Chemical analyses and infrared absorption spectra show that Ca-brittle mica-beidellite has a large Al-for-Si substitution in the tetrahedral sheets of 2: 1 silicate layers.

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We analyzed the clay mineralogical composition of twelve samples of weathered granitic rocks collected at Saga, Fukuoka and Kumamoto Prefectures. Halloysite was a principal mineral accompanied by mica and vermiculite. A “high-charge” smectite was found in the two of twelve samples but in small quantities. This mineral shows a basal spacing of 18 Å on Mg-saturation and glycerol-solvation and of 10 Å upon K-saturation and air-drying.
The 53-200pm of the samples having “high-charge” smectite did not contain vermiculite, different from the other samples. Mica dominating them was a dioctahedral mineral. Thus, some dioctahedral mica may be transformed into “highcharge” smectite and not into vermiculite.

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Thermogravimetric studies on the St. Jean Vianney clay from Quebec, Canada, have indicated four major thermal events. These events are best presented by means of the Derivative Thermogravimetric (DTG) curve which, until now, has been presented primarily as a histogram DTG plot. However, the tangent DTG plot gives greater distinction between thermal events and locates nine thermal events; the original four as well as five sub-events. A comparison of two quickclays, the St. Jean Vianney clay and a Norwegian clay, using the tangent DTG plot shows the complex mineralogical nature of the Canadian quickclay, while the Norwegian clay appears to have a relatively simple mineralogy.

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Fig Tree shale, one of the early Archean sediments occurred in the Swaziland System in South Africa, was examined for clay minerals. These minerals found in the shale are chlorite and illite with chlorite predominance. The chlorite is a typical Mg-, Fe-chlorite and is likely the IIb polytype. The illite could not be specified as to its polytype. An examination by an analytical electron microscope of individual particles reveals that the chlorite is fairly uniform in chemical composition, whereas the illite may vary to phengite. The chlorite and illite are probably formed during the burial diagenesis, considering the shale's age 3 billion years old. These two clay minerals are perhaps the oldest terrestrial clay minerals that are identified and characterized chemically.

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