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Rhyolite Vesicules

Chemical Process (Vapor-phase Growth) - Closed system under ground

Required Geological Setting

Island arc volcanoes, Intra-oceanic arc volcanoes


Minerals in vesicules of rhyolites. Gas components in rhyolite magma is released in the cooling process of lava, and they form open spaces as vesicules in rhyolites. Minerals are observed in vesicules as euhedral crystals grown from gas or liquid in vesicules. As rhyolites have low viscosity, vesicules are usually flat elongated to the direction of the flow.

Rhyolite Vesicules

Distribution of vesicule-producing rhyolites described in this site. Yellow lines are volcanic fronts.

Early stage (Host sides) >> Late stage (Center of visicules)

Tridymite (Wedged) >> Tridymite (Platy)+Fayalite >> Tridymite (Platy)+Osumilite >> Fayalite

Tridymite (Platy) >> Quartz >> Garnet (Almandine-Spessartine)


  • Kiyomizu (Lava, Osumilite)
  • Kozu Island (Lava, Osumilite)
  • Tsukigase (Lava, Osumilite)
  • Wada Pass (Lava, Spessartine)

Related Occurrences

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