An interstratified chlorite-montmorillonite mineral was found as an alteration mineral of tuff and tuffaceous sediments in the Neogene Tertiary “Green Tuff” near the Yamakata-machi, Kuji-Gun, Ibaragi Prefecture.
The <2μ fraction obtained by the sedimentation method contains about 3.2% quartz as an impurity. Chemical composition: SiO₂ 37.82%; TiO₂ 0.22%; Al₂O₃ 14.72%; Fe₂O₃ 6.47%; FeO 8.90%; MgO 14.36%; MnO 0.37%; CaO 1.81%; Na₂O 1.10%; K₂O 1.10%; H₂O (+) 7.10%; H₂O (-) 6.44%; total 100.41%. After subtracted 3.2% quartz from the chemical analysis, the structural formula was obtained as (Ca_0.357Na_0.391K_0.258) (Al_1.563Fe⁺³_0.895Fe⁺²_1.369Mg_3.938) (Si_6.371Al_1.629) O₂₀ (OH)₁₀. nH₂O.
X-ray examination of the natural material shows a reflection at about 31Å and its higher orders, but they make an irrational series. The montmorillonite-like layers expand with ethylene glycol and contract with heat treatment similar to montmorillonite. X-ray analysis revealed that the interstratification is produced by two component stacking of about 60% chlorite-like layers and about 40% montmorillonite-like layers. DTA and I. R. data are also described in this paper.

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Petroblastesis resulted from the coarsening of the constituting minerals is significant in the gabbros of the Hidaka metamorphic belt. Particularly plagioclase shows the change of crystal habit which is signified by the ratio of the length [001]/[010], in due corse of the petroblastesis. The fine grained facies which has the plagioclase of lath shape, otherwise of granoblastic, recrystallizes to columner plagioclase indicating gabbroic igneous texture, and then the coarse facies is produced by porphyroblastesis. It seems reasonably that there is a discontinuity between the formation of fine facies and petroblastesis. There might be an episode of metamorphism in between.

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Mineral composition and optical properties of the constituent minerals of beach sands in some sea-coasts in Kagoshima Prefecture, south Kyushu, are given in this paper. The relationship between gelogy of the provenance and the mineral composition of the beach sands is also discussed on each sea-coast area.
On the mineral composition, beach sands at Fukiagehama and Shibushi sea-coasts are characterized by the material which was derived from so-called “Shirasu” (pyroclastic flow deposits), those at Uchinoura sea-coast by the material which was drived from granodiorite, and those at Ibusuki sea-coast by the material which was derived from basic volcanic rocks, respectively. In short, the characteristics observed in both the mineral composition and the optical properties of the constituent minerals of beach sands reflect remarkably geology of the original source area of the material.

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