This is an old revision of this page, as edited by 217.81.149.224 (talk) at 21:28, 26 August 2004 (de:). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 21:28, 26 August 2004 by 217.81.149.224 (talk) (de:)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)
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.
on Tenerife, Canary Islands. Density of specimen
approx 0.25 g/cm. 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 Misplaced Pages by expanding it. |