VESICULAR TEXTURE

'Vesicular texture' is a volcanic rock texture characterised by, or containing, many vesicles. The texture is often found in extrusive aphanitic, or glassy, igneous rock. The vesicles are small cavities formed by the expansion of bubbles of gas or steam during the solidification of the rock.
A related texture is amygdaloidal in which the volcanic rock, usually basalt or andesite, has cavities, or vesicles, that are filled with secondary minerals, such as zeolites, calcite, quartz, or chalcedony. Individual cavity fillings are termed amygdules (American usage), or amygdales (British usage). Sometimes these can be sources of semi-precious stones such as agate.
Rock types that display a vesicular texture include pumice and scoria.