Lava balloon
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A lava balloon is a gas-filled bubble of lava that floats on the sea surface. It can be up to several metres in size. When it emerges from the sea, it is usually hot and often steaming. After floating
Lava balloons during the 2011–12 El Hierro eruption, floating on discoloured water
Lithophysa
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A lithophysa is a felsic volcanic rock with a spherulitic structure and interior cavity with concentric chambers. Its outer shape is spherical or lenticular. They vary in size from very small up to tw
Lava balloon
…the Canary Islands are on top of a hotspot. Furthermore, it has been proposed that lava balloons might be proof of shallow-water volcanic eruptions. Lithophysa Pumice raft…
A lithophysa from France
A collection of lithophysae "thundereggs"
Lithophysae from Richardson Ranch near Madras Oregon. 1, 2. Displaying typical plates and "sutures". 3, 4. A cluster with three spheroid centers. 5, 6. Example of slow fill structure layers with a large opal layer at the bottom. Expansion is controlled by where the water was located in the structure. 7. "Dimple" and "pimple" where expansion began on an inner shell. 8. Fortification agate
Spheroids form in high silica magmas