igneous
Pumice
Pumice (Vesicular Felsic Igneous Rock)
Hardness: 6 on the Mohs scale; Color: Light gray, white, yellowish, or greenish; Luster: Dull; Crystal structure: Amorphous volcanic glass (vesicular texture); Specific gravity: Very low (typically less than 1.0, meaning it floats on water).
- Hardness
- 6 on the Mohs scale
- Color
- Light gray, white, yellowish, or greenish
- Luster
- Dull
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Physical properties
Hardness: 6 on the Mohs scale; Color: Light gray, white, yellowish, or greenish; Luster: Dull; Crystal structure: Amorphous volcanic glass (vesicular texture); Specific gravity: Very low (typically less than 1.0, meaning it floats on water).
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich felsic lava cools rapidly, trapping gas bubbles within the glassy matrix.
Uses & applications
Used in lightweight concrete, landscaping, abrasive soaps, horticulture, and personal care (exfoliating pumice stones).
Geological facts
Pumice is one of the only rocks that can float on water due to its high porosity and trapped air chambers.
Field identification & locations
Easily identifiable in the field by its extremely light weight, pale color, and characteristic sponge-like vesicular texture with numerous small holes.
