Tobermorite rich in Al and with the basal spacing of 11Å was synthesized by treating zeolite (clinoptilolite)-lime mixtures under saturated steam pressure and at temperatures of 90-180°C. The synthetic tobermorite was found anomalous in the thermal behavior; the basal spacing of 11.4-11.7Å is not changed significantly by heating for 24 hours at 300°C or for 14 days at 700°C, until conversion to wollastonite occurs at 800°C. About 16% of Si in the synthesized tobermorite is substituted by Al from clinoptilolite. This substitution causes the increase of the basal spacing. The main Si-O lattice vibration indicated by the infrared spectra does not shift as the result of such substitution, but the bands at 1220 and 1065cm^-1 of Al-free tobermorite are found to shift to lower frequency region. The synthetic tobermorite is platy with a cleavage after (001) and is elongated parallel to b.

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A structure gap found in the natural lead-bearing barite was also observed indirectly on the precipitated BaSO₄-PbSO₄ solid solutions by the measurement of i. r. spectra, heat of precipitation, dissolution, rate of lead and co-precipitation of strontium and calcium with the solid solutions. The system may then be in a metastable state.

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Two-dimensional regular aggregates of thin flakes of some layer-silicates and gold were studied under the electron microscope, and those of SiC crystals by optical microscopy and X-ray diffraction. The results of the observations were interpreted in terms of the concept of compound tessellation, and some examples of ‘pseudo compound tessellation’ were presented. It was concluded that when crystals of layer structure come into contact with each other, they prefer to have their basal planes in common and to take mutual crystallographic orientations in which as many lattice points as possible per unit area in the basal plane of one of crystals fall into exact or approximate coincidence with those in the adjacent crystal.

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