Vesicular texture: Magma typically has some gas in solution. During eruptions, that gas effervesces out of solution, like CO2 bubbling out of a soda. As the magma freezes, these bubbles are preserved as vesicles, and rocks containing them are called vesiclular. Image: Scoria is a highly vesicular volcanic rock. It usually has a basaltic composition, but this is not a defining parameter. It just has to be very porous. Tenerife, Canary Islands. Width of sample is 7 cm. (from sandatlas.org)
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