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.
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