igneous
Pumice
Pumice (Vesicular Felsic Igneous Rock)
Hardness of 6 on the Mohs scale, typically white, grey, yellowish, or brown in color, dull to earthy luster, vesicular crystal structure with numerous gas cavities, specific gravity less than 1.0 (it floats on water).
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Physical properties
Hardness of 6 on the Mohs scale, typically white, grey, yellowish, or brown in color, dull to earthy luster, vesicular crystal structure with numerous gas cavities, specific gravity less than 1.0 (it floats on water).
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich felsic lava cools rapidly, trapping gas bubbles within the rock matrix before they can escape. Geological age varies widely depending on the eruption site.
Uses & applications
Widely used in lightweight construction aggregates, abrasive soaps, cosmetic exfoliants, horticulture as a soil amendment, and stonewashing jeans.
Geological facts
Pumice is one of the few rocks that can float on water due to its high porosity and trapped air vesicles. When massive underwater volcanoes erupt, they can create huge floating rafts of pumice that drift across the oceans for months.
Field identification & locations
Easily identified by its extremely light weight, pale color, and vesicular 'frothy' texture full of holes. Found globally near regions of recent or ancient volcanic activity, particularly around subduction zones and island arcs.
