The writer proposed a hypothesis concerning the manner of orientation of quartz crystals in tectonites ; and it has been found that this hypothesis, though a rough one, is very helpful in understanding qualitatively various facts as to the manner of orientation of quartz crystals., That is ; the writer assumed that the quartz crystal has crevices running parallel to (1010), and that the presence of the crevices brings about the strain-hardening.,

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Hydrozincite, as a white powder crusting brown-coloured drusy hemimorphite, has been analyzed., The Sample was obtained from the Nakatatsu Mine, Fukui Prefecture, one of the famous zinc-lead mines in Japan., It consists, under the microscope, of minute fibrous crystals, lining perpendicular to the surface of the crust., The optical properties are : straight extinction, elongation positive, possibly biaxial negative, with α=1., 649, γ=1., 704, Sp., gr., 3., 59 (26°C)., The result of the chemical analysis follows : ZnO 66., 70%, CaO 2., 69, Al₂O₃ 1., 17, Fe₂O₃ tr., CO₂ 16., 26 Insol., 0., 26, H₂O (+) 11., 75, H₂O(-) 1., 55, Total 100., 38., These may be expressed by the formula Zn₅(CO₃)₂(OH)₆·H₂O., An X-ray powder photograph taken with Cu K_α compares favorably with that of hydrozincite from Deming, New Mexico.,

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The purpose of this study was to determine the stratigraphic relation between Lepidocyclina limestones exposed at Simosiraiwa and Ono, 5 km., E and NE respectively of Syuzenzi, Izu, and the Yagasima Group which from the foundation of Izu penisula., Tertiary rocks exposed in the area studied consist of a complex of pyroxene-andesites and dacite tuffs., In the latter complex are included flows of pyroxene-andesites and dacites., The limestones occur in the apparently upper horizon of the dacite tuff complex., Generally speaking, the dacite tuff complex overlies that of pyroxene-andesites., At the junction of the two complexes, andesitic and dacitic pyroclastics grade to one another., Again, layers of dacite tuff are sometimes intercalated between lavas and pyroclastics of the andesite complex., These facts, taken in conjunction with the similarity of the nature of hydrothermal alteration of the rocks of the two complexes, strongly indicate that the andesite and dacite complexes were deposited successively., In the limestones we found fossils listed in Table 2, from which the age of the dacite tuffs is determined as older Miocene, or F₁ according to the "letter nomination" recently proposed by N., IKEBE, K., KANEHARA, and K., HUZIWARA., The andesite complex may also belong to the same general age., The andesite complex resembles closely the Yugasima Group exposed at the type locality Yugasima, 9 km., S of Syuzenzi, especially in that the rocks suffer propylitization., There is no doubt that the andesite complex of the area studied belong to the same group., The age of the Yugasima Group is therefore olderMinocene or F₁/

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