| Revision as of 17:09, 11 June 2004 editGeoGreg (talk | contribs)Extended confirmed users4,017 editsm typo← Previous edit | Revision as of 05:11, 31 July 2004 edit undoDcoetzeeBot~enwiki (talk | contribs)3,108 editsm Derrick Coetzee - Robot-assisted disambiguation: Gram (unit)Next edit → | ||
| Line 5: | Line 5: | ||
| <div style="float:left;margin-right:0.5em;text-align:center"> | <div style="float:left;margin-right:0.5em;text-align:center"> | ||
| ]<br> | ]<br> | ||
| <small>''Specimen of highly porous pumice from ] volcano <br>on ], ]. Density of specimen <br>approx 0.25 ]/]. Scale in ]s.''</small></div> | <small>''Specimen of highly porous pumice from ] volcano <br>on ], ]. Density of specimen <br>approx 0.25 ]/]. Scale in ]s.''</small></div> | ||
| It is considered a ] 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 ]. It is widely used to make lightweight ] and as an ], especially in polishes and ] exfoliants. | It is considered a ] 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 ]. It is widely used to make lightweight ] and as an ], especially in polishes and ] exfoliants. | ||
Revision as of 05:11, 31 July 2004
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. |