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Earth Materials
Minerals | Rocks

Volcanic Products
Pyroclastic Rocks

Pyroclastic rocks are composed of fragmented volcanic products ejected from explosive volcanic eruptions of viscous silica-rich magmas. Individual eruptive fragments are called pyroclasts ("fire or hot fragments"). Once pyroclasts have fallen to the ground they remain as unconsolidated tephra unless hot enough to fuse together or lithify through compaction and cemetation into a pyroclastic rock, a tuff.

Gas content of magmas
Lava Flows