Dacite Vesicules
Chemical Process (Vapor-phase Growth) - Closed system under ground
Occurrence
Minerals in dacite vesicules.
Required Geological Setting
Island arc volcanoes, Intra-oceanic arc volcanoes
Occurrence
Minerals in vesicules of dacites. Gas components in dacite magma is released in the cooling process of lava, and they form open spaces as vesicules in dacites. Minerals are observed in vesicules as euhedral crystals grown from gas or liquid in vesicules. Dacites form lava dome because of its high viscosity. Vesicules are distributed at the upper parts of domes, and are very few at the lower parts. Vesicules in dacites often exhibit bicone shape.
Distribution of dacite vesicules described in this site. Yellow lines are volcanic fronts.
Early stage (Host sides) >> Late stage (Center of visicules)
Tridymite (Wedged) >> Tridymite (Wedged)+Pargasite >> Tridymite (Wedged)+Fayalite >> Quartz >> Garnet >> Magnetite >> Laumontite+ Wairakite >> Stilbite
Localities
- Kajiya (Intrusive)
- Kami-Taga (Intrusive)