A new method of recording several layers of the reciprocal lattice simultaneously on a single photograph is proposed.
The method is a modification of the Weissenberg method with the film moving spirally on the surface of a cylindrical screen with several slits. The geometry of the diffraction patterns recorded by this method is, in general, different from those of the conventional one. The method is appreciably complicated in its mechanical aspect, but it has the great advantage of recording several reciprocal layers by a single exposure.

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Mineralogical data of sericite found near the Yoji pass, Ozawa-mura, Kanragun, Gumma Prefecture, are reported in this paper. The material is white powder with silky luster and occurs as a hydrothermal alteration product of quartz-diorite. Specfic gravity is 2.87 The result of the chemical analysis is SiO₂ 47.65, TiO₂ 0.10, Al₂O₃ 37.03, Fe₂O₃ 0.01, FeO tr., MnO tr., MgO 0.04, CaO tr., K₂O 9.02, Na₂O 0.76 H₂O(+) 4.97, H₂O(-) 0.73, P₂O₅ 0.02, total 100.33%, and this gives the structural formula of (Na_0•09K_0•76)Al_2•00(Al_0•87Si_3•13)O₁₀(OH)_2• The d. t. a. curve shows two endothermic peaks at 635°C. and 980°C.. X-ray studies of a pre-heated specimen revealed that the final destruction of the sericite lattice occurs at about 970° to 1, 000°C., mullite appears at 1, 000°C. and, that at 1, 100°C. sericite is completely transformed into mullite. The (060) spacing is 1.501Å., which indicates that the specimen is of the dioctahedral type.
Although the sericite leached by hot concentrated sulphuric acid displays X-ray powder lines different from those of original specimen, the results of acid treatment confirmed that the sericite is more durable than chlorite to acid attack.

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The areas of internal and surface X-ray reflexions on the precession photograph are theoretically derived for any crystal habit and are experimentally demonstrated as background patterns for two important cases. Considerations presented here seem to be useful for the estimation of absorption in precession photography.

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A white powdery clay mineral with 28.8Å. spacing was found in the kaolinite vein of the Uku mine, Yamaguchi Prefecture. The interplaner spacings of stronger X-ray powder diffraction lines of the mineral are as follows: 28.8±0.1, 14.5±0.1, 4.82±0.02 and 1.4893±0.0005Å.. The 14.5Å. line shifts to 15.4±0.2Å. and the 28.8Å. line is persistent in the temperature range from 20° to 300°C., but completely disappears above 400°C.. The 14.5Å. line is replaced by the 12.4Å. line at 400°C.. which is persistent up to 600°C. but disappears above 700°C. At 1200°C. the specimen is transformed to mullite.
It is considered that, as T. Sudo et al. have already pointed out, the unusually long spacing of 28.8Å. is the result of a regularly alternating stacking of two kinds of layer lattices; one is the ordinary montmorillonite lattice with the basal spacing of about 14.8Å. and the other is a hypothetical aluminium chlorite lattice with the basal spacing of about 14.0Å..

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Pyrosmalite, (Fe, Mn)₈ Si₆O₁₅ (OH, CI)₁₀, occurs abundantly as an important ore-forming mineral at the Kyurazawa mine, Tochigi Prefecture. It is hexagonal, with a₀=13.40Å. and c₀=7.135Å. The tabular or prismatic crystals are often found in vugs in the coarse granular aggregate of pyrosmalite and knebelite.
Basal cleavage is perfect, ω=1.671, ε=1.639, uniaxial negative; Sp. G.=3.14. More than 1500 tons of the manganese-iron ore containing 23-24% Fe and 24-23% Mn, and consisting of knebelite, pyrosmalite and the other manganese silicate minerals have been shipped from this mine for metallurgical uses since August, 1956.

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