igneous
Pumice
Pumice (Volcanic Glass Foam)
Hardness: 6 on the Mohs scale. Color: White, grey, yellowish, or brownish. Luster: Vitreous to dull. Crystal structure: Amorphous (volcanic glass with vesicular texture). Cleavage: None. Specific gravity: Less than 1.0 (it floats on water).
- Hardness
- 6 on the Mohs scale
- Color
- White, grey, yellowish, or brownish
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6 on the Mohs scale. Color: White, grey, yellowish, or brownish. Luster: Vitreous to dull. Crystal structure: Amorphous (volcanic glass with vesicular texture). Cleavage: None. Specific gravity: Less than 1.0 (it floats on water).
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich, felsic to intermediate lava rapidly cools and depressurizes, causing gas bubbles to become trapped in the solidifying glass.
Uses & applications
Used in lightweight construction aggregates, abrasive soaps, pumice stones for personal care, horticulture as a soil conditioner, and industrial filtration.
Geological facts
Pumice is one of the only rocks that can float on water due to its high porosity and trapped air bubbles. It has been used for centuries as an abrasive and in building materials, famously used in the construction of the Roman Pantheon.
Field identification & locations
Easily identified by its extremely light weight, frothy vesicular texture, pale color, and ability to float in water. Found globally in regions with recent volcanic activity, such as Italy, Turkey, Greece, the United States, and New Zealand.
