An example of a mineral with low specific gravity is pumice. Pumice is a volcanic rock that is formed when magma rises to the surface of the Earth and releases gas bubbles. The gas bubbles cause the magma to become frothy, and when the magma cools, the bubbles are trapped in the rock, giving it a lightweight, spongy texture. Pumice has a specific gravity of around 0.5, which means it is less dense than water and can float on water.