The Bonten bedded manganese oxide deposit of the Miyazaki Mine, Miyagi Prefecture occurs in the montmorillonitized tuff of middle Miocene age. The ore minerals of this deposit consist mainly of manganite, lithiophorite and hollandite with a small quantity of psilomelane. In this report, lithiophorite (new find in Japan) was examined by X-ray diffraction, chemical and differential thermal analyses. This mineral occurs as bluish black aggregates of very fine crystal. Its chemical composition is, Mn0₂ 53.11%, MnO 6.55%, CoO 1.18%, CaO 1.44%, MgO 2.69%, BaO 3.99%, Na₂0 1.00%, K₂0 0.94%, Li₂0 0.57%, Si0₂ 5.87%, Al₂0₃ 8.56%, Fe₂0₃ 1.19%, H₂0(+) 10.59%, H₂O(-) 2.46%, total 100.14%. The X-ray diffraction patterns shown good agreement with those of lithiophorite from White Oak Mt. reported by Fleischer and Richmond (1943). The differential thermal analysis curve is characterized by a single endothermic peak at approximately 490°C which is due to the transformation to hausmannite.

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Thermal transformation of manganophyllite in air has been studied in the temperature range up to 1200°C, using the differential thermal, thermogravimetric, and X-ray analyses. A correlation of the thermal data with the phase determinations shows that manganophyllite pursues the reaction process shown in the following schema with increasing temperature, and transforms into two phases, i. e. olivine and leucite, at high temperature.
partial dehydration main dehydration
Manganophyllite olivine leucite
braunite
increasing temperature

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Two groups of rocks in the Oki metamorphics, in Dogo Island were distinguished in 1961. The older consists mostly of regionally metamorphosed biotite gneiss and granitic migmatite, and the younger of augen gneiss.
Special attention was given to the alumino-silicate-bearing rocks which occur as melanocratic bands within the biotite gneiss. The granitization process of the melanocratic band differs from that of leucocratic layer, which was activated by the propagation of replacement fronts, i. e. basic front, alkali-Al front, and SiO2-K20 front associated with hydration successively.
These rocks belong to the sillimanite zone in general sense of meta-morphic grade. It is important to note that sillimanite does not occur uniformly in this zone, but only in a very limited rock facies.
Younger augen gneiss has been transformed definitely from preexis-ting metamorphics by the addition of quartz-potash-feldspar materials under the hydrous condition accompanied by intense mylonitization.
It is concluded that the two stages of metamorphism in the Dogo district correspond well to the older and the younger (Funatsu) stages of plutonism distinguished in the Hida metamorphic complex.

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The average chemical compositions of all rock types of the Aso volcano are calculated by chemical analyses, as shown in Table 3 with their norms.
From the comparison of these chemical compositions with the average compositions of Japanese effusive rocks, it is noted that the contents of Al₂O₃, Na₂0 and K₂0 are high, while those of CaO and FeO+Fe₂O₃ are low.
The alkali-lime index of the Aso volcano is 59.4 showing its alkalic nature.
In spite of the low contents of Si02 of the these rocks normative olivine is calculated only in IVb-c type rocks of Kishima-dake group. Normative C and Hm rarely are present in acidic rocks. Normative feldspars of the rocks of Neko-dake are to Ab side slightly lower in Or molecule than the other rocks, as seen in Fig. 2. Normative pyroxenes of Neko-dake are characterized by the high content of En, and these of Eboshi-dake group are very low in Wo content. As a whole, normative pyroxenes of this volcano are poor in Wo, owing to the presence of abundant hypersthene in mode.

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