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Roger Weller, geology instructor

by Scott Meyers
Physical Geology
Spring 2011


Pumice, The Rock Not Scared of Water

          There is a rock that gets along with water quiet well. When rocks are submerged in water, they tend to sink because of their weight. They donít float, but pumice does. Pumice is the only rock that can float on water. Pumice has little gas pockets to help stay above water. Another reason why it can stay above water is that itís so light. It has hardly any weight. You can call these pockets their lifejacket. Pumice rocks are igneous rocks which were formed when lava cooled quickly above ground. Pumice is actually a rock that is classified as a glass because is contains no crystals or a mixture of minerals. It has a vesicular texture because of the little gas bubble trapped within the rock. Pumice is a lighter colored rock as you can see in picture below.


          Another reason why pumice is water friendly is it made into soap. In 1893 a small company started to combine soap with pumice. The soap was distributed out St. Louis, Missouri. The soap was called Lava Soap. Because itís unique from and abrasion properties, it was use to wash and clean the heavy greasy and tar spots from your skin. The soap not only gets the skin clean from them nasty stains on your skin, but also helps moisturize the skin too. The company was sold to Proctor & Gamble and then sold once again to WD-40. Today you can find this soap in almost any stores.





          Pumice has a lot more uses than soap. It is used in the cosmetics industry as an exfoliating pad, scouring stones and as an additive in creams and lotions. Pumice's hardness makes it useful as an abrasive and its light weight gives it an advantage for use as large decorative rocks for landscaping. Pumice has been used since Roman times to help build structures and buildings. Pumice is used for decorative and landscaping purposes. It is not as expensive as hand cut rock. Pumice also is used to make lightweight cement and concrete. It helps smooth concrete, is resistant to harsh weather and contributes to cement's polished appearance.

          A rock is just not only a rock. Pumice can be used in many different types of ways. Rocks are all special in their own way. They can be used for many different proposes. They come in different sizes, colors, and forms. A rock is just not an ordinary rock. When does a rock has to be scared of water?