| Revision as of 19:50, 24 December 2003 editJll (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers10,640 edits + How it is formed← Previous edit | Revision as of 20:03, 1 January 2004 edit undoJll (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers10,640 editsmNo edit summaryNext edit → | ||
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| <small>''Top stone is ], below that is pumice<br> and in lower right hand color is ] (light color)''</small><br> | <small>''Top stone is ], below that is pumice<br> and in lower right hand color is ] (light color)''</small><br> | ||
| ]</div> | ]</div> | ||
| '''Pumice''' is a light, porous type of pyroclastic ]. It is formed during explosive ] eruptions when liquid ] is ejected as a froth containing masses of gas bubbles. As the lava solidifies, the bubbles are frozen into the rock. Any type of igneous rock - ], ], ] or ] - can form pumice given suitable eruptive conditions. | '''Pumice''' is a light, porous type of ] ]. It is formed during explosive ] eruptions when liquid ] 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 - ], ], ] or ] - can form pumice given suitable eruptive conditions. | ||
| 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 20:03, 1 January 2004
File:Different rocks at Panum Crater-300px.jpg
Top stone is obsidian, 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.
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.
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