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

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


Hiraiso, Hiraiso Seashore


Alkaline metasomatic rocks of Heulandite-Analcime 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.


Outcrop of tuff breccia of the Shirahama Group. The outcrop consists of tilted alternating beds comosed of larger fragments and smaller fragments. The beds of larger fragments are composed of brecciated pillow lava, and the beds of smaller fragments are hyaloclastite. It turned greenish by propylitization alteration.

Reported Minerals

Mineral Assemblages

  • Heulandite-Ca - Mordenite
  • Dachiardite-Ca
  • Chalcedony


Related Occurrences

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