Cretaceous Taiheizan composite granitic pluton occurs in the Taiheizan mountains, central Akita prefecture, Northeast Japan. The rocks are divided into the East and West masses by the Kyowa-Hitachinai mylonite zone, which resulted in right lateral movement. The East mass is composed of mainly weakly foliated medium to coarse-grained hornblende biotite granodiorite and tonalite. They contain magnetite, but these magnetic susceptibilities average 8.08 × 10−3 SI units, which are relatively lower than those of typical magnetite-series Kitakami granitic rocks. On the other hand, the West mass is composed of mainly foliated granodiorite and tonalite, which belong to the ilmenite-series due to the absence of magnetite. Both rocks have different chemical features. The magnetite-series East rocks have lower contents of Al2O3, Na2O and higher contents of MgO, K2O than the ilmenite-series West rocks. Trace element contents show that the East rocks have higher contents in Cr, Ni, V, but lower in Zr. However, the chemistries of both rocks resemble those of Abukuma granitic rocks as compared with those of Kitakami rocks. The reported K-Ar ages of the East and West masses also show the same ages from Abukuma rocks. Therefore, I conclude that the Taiheizan granitic rocks belong to the Abukuma belt, and the Kyowa-Hitachinai mylonite may coincide with the boundary of low magnetic susceptibility magnetite series rocks and ilmenite series rocks in the Abukuma granitic rocks.
High temperature volcanic sublimates including so-called “molybdenum blue” sampled around the high-temperature fumaroles at Iwodake volcano, Satsuma-Iwojima, Kyushu, Southwestern Japan, were characterized by X-ray powder diffraction, X-ray micro-diffraction, Raman micro-scattering, electron microprobe and X-ray photoelectron spectroscopic analyses. The identified minerals are molybdenite, sphalerite, tugarinovite, molybdite, hematite, halite, sylvite, anglesite, wulfenite, quartz, tridymite, cristbalite and potassium alum. Occurrences of both tugarinovite and molybdite are observed in Kudriavy volcano, too, and the coexistence of their minerals is characteristic of high-temperature volcanic sublimates. The molybdenite and sphalerite from Iwodake are exceedingly rich in Re (up to 0.77 wt%) and In (up to 1.69 wt%), respectively, distinguished from those of a different origin by chemical composition. The molybdenite consists of both of 3R and 2H1 polytypes. Sublimates from Iwodake and Kudriavy volcanoes are similar in mineralogy. Although the difference in the host rock arises between the Iwodake (rhyolite) and the Kudriavy (basaltic andesite) volcanoes, their volcanic gases resemble each other in F and Cl contents. This resemblance might cause the similarity in sublimate mineralogy between these volcanoes.