The volume percentage of a rock that consists of Huge region of space that is unusually empty of galaxies. Voids are not entirely empty, but are underdense and contain far fewer bright galaxies than average. space. Vesicles appear in nature when they are produced within lava (extrusive aphanitic igneous rock) whose dissolved gases come out of solution (are released) due to the drop in pressure during an eruption. The resulting lava solidifies around the gas bubbles capturing their shape inside and outside the rock. Vesicles do Click on Term to Read More porosity is a type of porosity resulting from the presence of vesicles, or gas bubbles, in One of the three basic types of rock that also include sedimentary and metamorphic. Igneous rocks are formed by the solidification of magma and comprised predominately of silicate minerals. Based on bulk chemical analysis, igneous rocks can be grouped into four major groups based on their SiO2 content: 1. Felsic: Click on Term to Read More such as the pumice presented here. Vesicular porosity is very rare in meteorites and is often associated with slag, one of the most common meteorwrongs.