Skip to content
Science, Maths & Technology
Author:

Pumice

Updated Thursday, 28th September 2006

A brief description of the nature of pumice

This page was published over five years ago. Please be aware that due to the passage of time, the information provided on this page may be out of date or otherwise inaccurate, and any views or opinions expressed may no longer be relevant. Some technical elements such as audio-visual and interactive media may no longer work. For more detail, see our Archive and Deletion Policy

Pumice is a fine-grained volcanic rock. It is very light grey to medium grey in colour. It contains a lot of empty gas bubbles, so it is very light and looks rather like a sponge. Sometimes pumice is so light that it will float on water.

Pummice Copyrighted  image Icon Copyright: Weldon Schloneger | Dreamstime.com Pummice

How is it formed?
Pumice is formed when volcanoes erupt explosively. It comes from the same kind of magma which would form granite or rhyolite, that is, a magma that contains lots of silica (quartz).

Magma with lots of silica is usually thick and sticky. Some of the gases which cause the explosive eruption get trapped in the magma and form gas bubbles. These are preserved as holes when the rock cools as it comes flying out of the volcano.

 

Get closer to geology

 

 

Author

Ratings

Share

Related content (tags)

Copyright information

For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?