igneous
Pumice
Pumice (Vesicular Felsic Igneous Rock)
Hardness of 6 on the Mohs scale, colors range from white, grey, yellowish, to brown, dull to silky luster, extremely vesicular and porous texture, low specific gravity (often less than 1, allowing it to float on water).
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Physical properties
Hardness of 6 on the Mohs scale, colors range from white, grey, yellowish, to brown, dull to silky luster, extremely vesicular and porous texture, low specific gravity (often less than 1, allowing it to float on water).
Formation & geological history
Formed from explosive volcanic eruptions where frothy, gas-rich felsic lava cools rapidly, trapping gas bubbles within the glass matrix.
Uses & applications
Used in lightweight concrete aggregates, abrasive materials such as pumice stones for personal care, polishing compounds, and horticulture soil amendments.
Geological facts
Pumice is one of the few rocks that can float on water due to its high concentration of trapped gas bubbles. Large floating rafts of pumice can travel across oceans following submarine volcanic eruptions.
Field identification & locations
Easily identified by its extremely low weight-to-size ratio and visible vesicular (porous) structure. Commonly found in regions with recent or historical volcanic activity associated with subduction zones.
