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Obora Path

Toi, Izu city, Shizuoka pref., Japan




Alkaline metasomatic rocks of Laumontite-Albite zone

Vesicules of the andesitic to basaltic tuff breccia of the upper part of the early Pliocene (4.0 Ma) Shirahama Group. Tuff breccia is a part of pillow lava and hyaloclastite. Andesite and basalt of the upper Shirahama Group are tholeiitic, and have been subjected to propylitization alteration. The Shirahama Group unconformably overlies the Miocene Yugashima Group. Ages of sediments were determined by microfossils and K-Ar radiometric dating.

Obora Path

Outcrop of andesitic to basaltic tuff breccia of the Shirahama Group. The grayish-green host is tuff breccia composed of lapilli smaller than the coin. It turned greenish by propylitization alteration. The group of tabular white crystals is yugawaralite in the open space of the tuff breccia.

Reported Minerals

Mineral Assemblages

  • Chabazite - Wairakite - Mordenite
  • Yugawaralite
  • Stilbite


Related Occurrences

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