igneous
Pumice
Pumice (Volcanic Rock)
Hardness: 6 on the Mohs scale, Color: White, cream, gray, yellowish, or brown, Luster: Dull to earthy, Crystal Structure: Amorphous (glassy volcanic foam), Cleavage: None, Specific Gravity: Less than 1.0 (it typically floats on water).
Identified More igneous →
Explore Pumice in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 on the Mohs scale, Color: White, cream, gray, yellowish, or brown, Luster: Dull to earthy, Crystal Structure: Amorphous (glassy volcanic foam), Cleavage: None, Specific Gravity: Less than 1.0 (it typically floats on water).
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich felsic to intermediate lava rapidly cools and depressurizes, trapping gas bubbles within the glassy rock matrix.
Uses & applications
Widely used in abrasive cleaners, personal care pumice stones, lightweight aggregate in construction, concrete manufacturing, and horticulture.
Geological facts
Pumice is one of the few rocks that can float on water due to its high porosity and trapped gas bubbles.
Field identification & locations
Easily identified by its extremely low weight, vesicular (foamy/bubbly) texture, and light color. Commonly found near active or historical volcanic regions worldwide.
