Pumice Facts
Pumice is an igneous rock, which means it is formed from the magma or lava of a volcano. Pumice is full of holes and comes in a variety of colors. A stone of sizable economic worth, pumice can be found in science classrooms, museums, in concrete, in housing materials and in personal care products.
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Features
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Colors can be white, shades of gray, reddish black, black and can also have bands of color. Lighter colored pumice can mean that there is a higher amount of silica.
Small lines in the pumice can be formed when the lava continued to move during cooling.
Pumice has a combination of fine threads of glass, thin walls of glass, along with holes of various shapes. This airiness results in a light weight.
Function
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Pumice is used as an exfoliate for removing dead skin cells and to increase circulation.
In the production of jeans, pumice is the abrasive used to create the stone washed style.
Small grained pumice is used to make fine grain cement.
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Formation
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Pumice forms from explosive volcanic eruptions and from any type of magma (andesite, basalt, dacite, rhyolite). Pumice is pyroclastic, igneous, volcanic cooled magma, containing a large amount of silica.
Inside of the magma is gas that caused it to 'foam' when it came out of a volcano. The pressure on the magma while in the ground kept the gases compacted but once the magma left the confines of the earth, now called lava, there wasn't anything to push in against the gas. The result is multiple gas bubbles push out. While the gas expands, the lava quickly cools. When lava cools quickly, the molecules don't have time to form crystal structures and form glass.
Geography
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Pumice can be found worldwide and even washes up on shorelines. Some of the countries that use pumice as an industry are Chile, Greece, Italy, Spain, Turkey and the United States.
Due to its porosity, pumice can be found as floating islands on water. Over time these islands sink, meaning that pumice is found on the floors of bodies of water.
Considerations
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"Pumex" is the Latin word for foam from which the word pumice is based. However there are other terms for this porous stone. While the term pumice is applied to large pieces of pumice, the term pumicite describes pieces ranging from ash to small grain.
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