What type of rock is known for its light weight and air-filled bubbles?

Pumice is a type of volcanic rock that is characterized by its light weight and presence of air-filled bubbles, which is a result of gas escaping during volcanic eruptions. This unique formation occurs when lava cools rapidly and traps gas bubbles, resulting in a porous texture that makes pumice much less dense than many other types of rock. The presence of these bubbles allows pumice to float on water, which further distinguishes it from other rocks.

In contrast, marble is a metamorphic rock that is denser and does not exhibit the same porous qualities. Granite, an igneous rock, is known for its toughness and crystallization, while limestone, a sedimentary rock composed primarily of calcium carbonate, also lacks the air-filled bubbles associated with pumice. This contrast in composition and structure highlights why pumice is specifically identified as the rock type characterized by its light weight and air-filled bubbles.