苗場,鳥甲火山のカルクアルカリ安山岩中のはんれい岩,ドレライト,玄武岩ゼノリスは地球化学的に大きく3つのグループに分けられる.第1のグループの苗場のはんれい岩Aは, MgO, Niに富み,アルカリに乏しく,一ノ目潟(2232), 箱根 (HKG1,KHG2)のはんれい岩ゼノリスと似て, REEに乏しいパターンを示す.このことと単斜輝石の高いAl^lV含量に基づくと,このはんれい岩Aは上部マントルの部分溶融により生成された初成マグマからの沈積相と考えられる.第2のグループの海川,一の目潟のはんれい岩はREEパターンから,第一のグループのような物質が取り除かれることにより生じた低アルカリソレアイトマグマから由来したものであろう.第3のグループの苗場のドレライト,玄武岩ゼノリス,鳥甲のはんれい岩ゼノリスは第1のグループよりMgOに乏しく,アルカリに富み,高アルカリソレアイトのそれに似たREEに富んだパターンを示し, Al^IVに乏しい単斜輝石を含むことから浅所での高アルカリソレアイトマグマの分化物と考えられる.
第1のグループのはんれい岩Aの同位体はεNd-₈₇Sr/₈₆Srダイアグラム上では, MORBよりインコンパチブル元素に富んだ北部フォッサマグナの浅間,妙高火山のそれに近く,それらとおなじマントル物質から由来したことを示している.

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Strontium isotope compositions were determined for 1 dacite, 2 low-silica rhyolites, 1 high-silica rhyolite and 2 phenocrystic hornblendes from Hime-shima volcano, Southwest Japan. The whole rocks increase in Rb and ⁸⁷Sr/⁸⁶Sr and decrease in Sr with increasing SiO₂. The high-silica rhyolite composition can be closely reproduced in terms of Rb, Sr and ⁸⁷Sr/⁸⁶Sr by model calculations of assimilation-fractional crystallization of the dacite magma: the material to be assimilated is granodiorite which is presumably spread beneath the volcano. The low-silica rhyolites have compositions close to a mixing line between the dacite and high-silica rhyolite in a Sr-⁸⁷Sr/⁸⁶Sr relation diagram, suggesting that they are mixing products of the dacite and high-silica rhyolite magmas. Hornblende phenocryst and its host dacite have virtually identical ⁸⁷Sr/⁸⁶Sr. On the other hand, hornblende in the low-silica rhyolite has ⁸⁷Sr/⁸⁶Sr between its host rock and the dacite. It is likely that the hornblende was derived from the end-member dacite magma and on the way to be in re-equilibrium with the melt phase of mixed rhyolitic magma when the magma erupted. Because the hornblende in rhyolite shows no sign of re-equilibration with respect to chemical composition, the tracer diffusivility of ⁸⁷Sr/⁸⁶Sr is likely to be higher than the chemical diffusivility.

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Two types of magmas exist at Nishiyama volcano, Hachijojima Island. One is plagioclase-controlled and the other is differentiated magma. The bulk chemistry of the first magma type is controlled by abundance of plagioclase phenocrysts with a constant liquid composition. That of the second type is possibly controlled by fractionation of plagioclase and mafic minerals from a basaltic magma.
Predominant is the plagioclase-controlled basalt at Nishiyama volcano. Summit eruptions invariably tap the plagioclase-controlled magma. Flank eruptions supply not only the plagioclase-controlled basalt, but rarely the differentiated basaltic andesite. These phenomena are similar to those observed at Izu-Oshima volcano. There must be something in common between the magma plumbing systems of Nishiyama and Izu-Oshima volcanoes.

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Some primary ore-textures which are composed of rhodochrosite or caryopilite were observed in manganese ores from the Sagadani mine, where locates in the northern Chichibu Belt, Japan. The rhodochrosite ore shows lenticular form, which consists of spherulites representing cross extinction between crossed nicols. The textures of caryopilite ores are classified to three types. The first is isotoropically massive between crossed nicols, being the most common texture. The second is drop-like in mossaic quartz grains. The drops show homogeneous birefringence without internal textures. The third is a texture resembling peas in a pod or a fine string-like texture, which is inferred to be biogenic origin.
All the textures composed of rhodochrosite or caryopilite are presumed to be formed by diffusion of manganese ions into gelatinous materials of siliceous or muddy sediments.

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