Chemical analysis of takanelite a new manganese dioxide mincral from Nomura mine, Ehime Prefecture gave; MnO₂70.39, MnO 13.06, MgO 0.22, CaO 2.66, BaO none, Na₂O 0.05, K₂O 0.05, Fe₂O₃ 1.34, Al₂O₃ 1.70, TiO₂ trace, SiO₂ 3.61, H₂O(+) 4.92, H₂O(-) 2.22, sum 100.22%. After deducting Al₂O₃, SiO₂, Fe₂O₃, H₂O(-) and a part of H₂O(+) (present as halloysite, goethite and quartz), it corresponds to (Mn⁺²_0.89 Ca_0.23 Mg_0.03)_1.15 Mn⁺⁴_3.94 O_9.00 1.3H₂O as O=9, or ideally (Mn⁺², Ca) Mn₄⁺⁴O₉•nH₂O with Mn⁺²⟩Ca and n=1.3. This is the Mn⁺² analogue of rancieite, (Ca, Mn⁺²) Mn⁺⁴₄O₉•nH₂O with Ca⟩Mn⁺² and n=3. Electron microprobe analyses of five different grains, using analysed rancieite, nsutite and todorokite as standards, gave Mn 60.5-62.3 and Ca 2.0-2.4, and Fe, Al and Si were not detected. These results validate the above analysis and deduction of impurities. Analyses of some other materials suggest the possible existence of a continuous solid solution series between rancieite and this mineral.
X-ray powder data are very similar to those of rancieite by Sorem and Gunn (1967) and by Richmond, Fleischer and Mrose (1969), and includes the strongest lines 7.57 (100) (1010), 4.43 (10b) (0002, 1120), 3.76 (25) (2020), 2.462 (15) (1123), 2.349 (20) (2023), 2.065 (10) (2133), 1.754 (7) (2243, 1015), 1.420 (17) (5052, 4260, 1126). The indexing is based on the hexagonal cell with a₀=8.68Å, c₀=9.00Å, Z=3.
Colour steel gray to black, luster submetalic to dull, streak brownish black, sp. gr. 3.41 (measured on impure material); 3.78 (calculated). Cleavage not observed. Vickers' hardness (load 100g) 480kg/mm²(average). In reflected light, yellowish gray, reflection pleochroism weak with yellowish white to yellowish light gray, anisotropism moderate with polarization colour of yellowish gray to light brownish gray. Etch reactions: HCI (conc.), HNO₃(conc.) and H₂SO₄ (conc.) tarnish slightly grayish brown, H₂SO₄ (conc. ) +H₂O₂ (20%) and SnCl₂ (sat.) quickly stain black.
The mineral occurs as irregular-shaped nodules, 1-15cm across, composed of a microscopic intergorwth with a small quantity of braunite, halloysite, goethite and quartz, in the oxidation zone of the braunite-rhodochrosite-caryopilite bedded deposit at the Nomura mine, Ehime Prefecture, Japan, in low grade metamorphosed cherts of Permian age.
The name is for the late Dr. Katsutoshi Takane (1899-1945), the former Professor of Mineralogy, Tohoku University, Sendai, Japan. Type material is preserved at Tohoku University.
The mineral and name were approved before publication by the Commission on New Meinerals and Mineral Names, IMA.

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The Ryugamori mass is one of the pre-Tertiary basement formations exposing at some places, in the Green Tuff Region of northcastern Japan. The mass is composed of the Paleozoic meta-slate and banded chert intruded by composite granitic pluton. According to the field observation, the pluton is divided largely into two groups: the older granitic rocks including schistose quartzdiorite (A₁ facies) and massive granodiorite (A₂ facies), and the younger (Tertiary) quartzdiorite to granodiorite (B₁ to B₂ facies). The latter develope mainly along the boundaries between the basement and the Tertiary formations.
Petrochemically the granitic rocks of this district are characterized by lower Al₂O₃ and higher MgO in comparison with the average granitic rocks of Japan. On the other hand, the younger granitic rocks can be discriminated by higher Fe₂O₃/Fe₂O₃+FeO and lower MgO/Fe₂O₃+FeO from the older granitic rocks. The chemical nature of the younger granitic rocks are generally in accord with the tertiary granitoids of northeastern Japan.

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The Akita-Komagatake volcano (1637.4m above sea level), located on the border between Akita and Iwate prefectures, northeastern Japan, crupted suddenly on September 18th, 1970. The eruption consisted of small amounts of lava flow and volcanic ejecta and occurred at the summit crater on the Medake central cone inside the Akita-koma-gatake, a Glen Coe-type caldera. Petrographically, the rock consists of phenocrystic plagioclase (An_94-62), olivine, hypersthene, augite and magnetite set in the groundmass of plagioclase, augite, hypersthene, pigeonite, magnetite and brown glass. There are conspicuous difference between this new lava and all of the previous lavas from this volcano. Namely, the new lava belongs to the Kuno's hypersthenic rock series (calc-alkaline series) and is intermediate andesite in composition, whereas the previous lavas belong to the pigconitic rock series (theoleiitic series) and are basalts and mafic andesites.

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