Book 12, Question 10
What Is Pumice, the Rock Full of Bubbles?
Pumice is a rock so full of bubble holes that it is mostly air. It forms when frothy lava cools quickly and the gas bubbles get trapped. It is so light that it floats on water!
More fun facts
- Pumice is volcanic rock so full of bubbles that it can float on water.
- It forms when bubbly lava cools so fast that the bubbles get trapped.
- Thin walls of glass separate the tiny holes in pumice.
- Reticulite, an even frothier rock, forms only in very high lava fountains, about 300 meters (1,000 feet) or more.
- Pumice is light colored and very light for its size.
Sources: U.S. Geological Survey, U.S. Geological Survey, National Park Service, Smithsonian
Questions kids ask
Why does pumice float?
It is full of trapped gas bubbles, which make it very light.