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Dohira River

Minami-Nomaki, Shimonita city, Kanra county, Gunma pref., Japan

Occurrence

Alkaline metasomatic rocks of Wairakite-Albite zone

The late Miocene (6.0 Ma) andesitic dike intruded in the Motojyuku Formation of the same age. The Motojyuku Formation is composed of andesitic tuff breccia and andesitic-dacitic dikes filling the late Miocene-Pliocene Motojyuku Caldera. Ages of volcanic rocks were determined by K-Ar radiometric dating.

Dohira River

Outcrop of an andesitic dike intruded in the Motojyuku Formation. The grayish-green host is andesite dike with fine white spots of anorthite phenocrysts. The white to pale brown vein is composed of calcite and wairakite. The white parts are wairakite, and the pale brown parts are calcite. The wairakite crystals are up to 1/3 of the scale coin.

Reported Minerals

Mineral Assemblages

  • Wairakite - Calcite

Localities

Related Occurrences

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