What Is Pumice Stone ? Pumice stone is a lightweight, volcanic rock formed when lava cools quickly and traps gas bubbles, resulting in a porous texture. This unique composition makes pumice an ...

A vast "raft" of volcanic rocks stretching over 150 sq km (58 sq miles) is drifting through the Pacific Ocean, scientists say. The sea of pumice - the size of 20,000 football fields - was first ...