The Ohmine granitic rocks of Miocene age (14 Ma) intrude into sedimentary rocks of the Chichibu, Shimanto and Kumano Groups in the central Kii peninsula, southwestern Japan. These granitic rocks occur as small high-level plutons in a N-S direction, namely from north to south, Dorogawa, Shirakura, Kose, Asahi, Tenguyama, Shiratani and Katago-Mukuro masses. Petrography and chemistry of these granitic rocks reveal I-type with north (Dorogawa and Shirakura masses) and S-type with south (Kose, Asahi, Tenguyama, Shiratani and Katago-Mukuro masses); the former characterized by the presence of hornblende and by low mole Al₂O₃/(CaO+Na₂O+K₂O) ratio, whereas the latter containing muscovite and the ratio higher than 1.1.
The I-type, Dorogawa mass consists of fine-grained porphyritic granodiorite and granite, with phenocrysts of euhedral to subhedral plagioclase, hornblende and biotite set in groundmass composed of quartz and orthoclase micrographic intergrowth and plagioclase. The I-type, Shirakura mass is made up of fine-grained porphyritic hornblende granite. The Dorogawa mass is distinguished from the Shirakura mass by the absence of orthoclase phenocryst and high MgO/(MgO+FeO^t) ratio. The I-types, especially the Dorogawa rocks, have higher CaO/FeO and Na₂O/K₂O ratios than the Southwest Outer Zone-type granitic rocks. The I-type, Shirakura granite is intruded by the S-type, Kose granite.
The S-type, Kose, Asahi, Tenguyama and Shiratani masses consist of porphyritic granite, while Katago-Mukuro masses are composed of granite porphyry accompanying a small amount of quartz porphyry. These S-type rocks commonly contain orthoclse phenocryst and muscovite, and rarely contain quartz-orthoclase micrographic intergrowth. The well known “Kumano acidic rocks” occurring to the southeast of the studied area are considered deroofing equivalent of the S-type granitoids.
The S-type, Tenguyama and Shiratani masses characteristically include clots of sillimanite (including fibrolite), andalusite, garnet, cordierite, orthopyroxene, biotite, corundum and green spinel. However, these minerals are absent in the country rocks and xenoliths. High-grade metamorphic rocks containing these minerals are also absent in the surface exposure of the central Kii peninsula.

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The granitic rocks in the Tsukuba area are divided into the following seven bodies from north to south, namely, coarse-grained granite, fine-grained granodiorite, medium-grained granodiorite, Kabasan fine-grained granite, Yamanoo fine-grained granite, porphyritic granodiorite and two-mica granite (Takahashi, 1982). Mineralogical characters of these granitic rocks are as follows:
(1) Plagioclase in the coarse-grained granite has a rim in the composition range, An 4-21. The composition range of plagioclase in the porphyritic granodiorite is An 28-42 in its tonalitic facies and An 20-30 in granodiorite to granite. In the other five bodies, the rim composition of plagioclase mostly ranges from An 20 to An 21 and the core composition generally ranges from An 20 to An 30.
(2) The Mg/(Mg+Fe+Mn) ratio of biotite in the coarse-grained granite ranges from 0.15 to 0.24, whereas it ranges from 0.23 to 0.38 in the other six bodies. The Si of biotite in the coarse-grained granite is up to 5.64, whereas it in the other six bodies ranges from 5.20 to 5.57.
(3) Amphibole in the coarse-grained granite is ferro-hornblende and its Na/(Na+K) ratio is 0.771.
(4) The features described above suggest that the coarse-grained granite is similar to that of the Sanyo zone and the granitic rocks in the other six bodies are similar to that of the Ryoke zone.

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Hydrohetaerolite, Zn₂Mn₄O₈. H₂O, was found in the oxidation zone of Maruyama copper-lead-zinc-manganese mine, southwestern Hokkaido. This is the second occurrence reported in Japan.
The mineral is brownish black. X-ray powder diffraction pattern shows that it is tetragonal with a₀ 5.72, c₀ 9.09Å, and space group I4₁/amd. Wet chemical analysis gives an empirical formula of (Zn_1.62Mg_0.56)_2.18Mn_3.88O_8.00• 1.13H₂O.

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