TrekGEO > Mineral Trail > Tokai region > Shizuoka pref. > Onigasaki

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Hama, Kawazu city, Kamo county, Shizuoka pref., Japan



Phenocryst of rhyolite in the lower part of the late Miocene (7.0 Ma) Shirahama Group. The Shirahama Group unconformably overlies the Miocene Yugashima Group. Ages of sediments were determined by microfossils and K-Ar radiometric dating.


Width: 30 mm. Outcrop of weathered rhyolite o fthe Shirahama Group. Phenocrysts were etched out on the surface. Rounded gray grains are beta-quartz, and platy opaque white crystals are orthoclase.

Reported Minerals

Mineral Assemblages

  • Rhyolite(Host) - Orthoclase - Beta-Quartz


Related Occurrences

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