Pumice

Hardness: 6 on the Mohs scale, Color: White, yellowish, grey, or brown, Luster: Dull to earthy, Crystal structure: Amorphous (volcanic glass), Specific gravity: Less than 1 (it floats on water)

Formed from explosive volcanic eruptions where frothy, gas-rich lava rapidly cools and depressurizes, trapping gas bubbles within the glassy matrix.

Used in lightweight concrete, landscaping, abrasive soaps, personal care products like pumice stones for skin exfoliation, and horticultural soil amendments.

Pumice is one of the few rocks that can float on water due to its extremely high porosity and trapped gas bubbles. It has been used since antiquity for exfoliating skin and as an abrasive material.

Easily identified by its extremely light weight, pale color, and vesicular (bubble-pocked) texture. Found worldwide near active or historical volcanic regions such as the Mediterranean, US Pacific Northwest, and parts of South America.