Encyclopedia  |   World Factbook  |   World Flags  |   Reference Tables  |   List of Lists     
   Academic Disciplines  |   Historical Timeline  |   Themed Timelines  |   Biographies  |   How-Tos     
Sponsor by The Tattoo Collection
Pumice
Main Page | See live article | Alphabetical index

Pumice

, below that is pumice and in lower right hand color is rhyolite (light color).]] Pumice is a light, porous type of pyroclastic igneous rock. It is formed during explosive volcanic eruptions when liquid lava is ejected into the air as a froth containing masses of gas bubbles. As the lava solidifies, the bubbles are frozen into the rock. Any type of igneous rock - andesite, basalt, dacite or rhyolite - can form pumice given suitable eruptive conditions.


Specimen of highly porous pumice from Teide volcano
on Tenerife, Canary Islands. Density of specimen
approx 0.25 g/cm3. Scale in centimetres.

It is considered a glass because it has no crystal structure. Pumice varies in density according to the thickness of the solid material between the bubbles; many samples float in water. It is widely used to make lightweight concrete and as an abrasive, especially in polishes and cosmetic exfoliants.

This article is a stub. You can help Wikipedia by [ expanding it].