igneous
Pumice
Pumice
Hardness: 6 on the Mohs scale; Color: Light gray, white, yellowish, or tan; Luster: Dull to earthy; Crystal structure: Amorphous (volcanic glass); Specific gravity: Less than 1.0 (it floats on water).
- Hardness
- 6 on the Mohs scale
- Color
- Light gray, white, yellowish, or tan
- Luster
- Dull to earthy
Identified More igneous →
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Physical properties
Hardness: 6 on the Mohs scale; Color: Light gray, white, yellowish, or tan; Luster: Dull to earthy; Crystal structure: Amorphous (volcanic glass); Specific gravity: Less than 1.0 (it floats on water).
Formation & geological history
Formed from explosive volcanic eruptions where felsic or intermediate magma is rapidly cooled and depressurized, causing dissolved gases to bubble out and become trapped as vesicles in the solidifying glass.
Uses & applications
Used in abrasive materials, lightweight concrete aggregate, horticulture as a soil amendment, and for personal care such as exfoliating stones.
Geological facts
Pumice is one of the very few natural rocks that can float on water due to its extremely high porosity and trapped air bubbles.
Field identification & locations
Easily identified by its extremely light weight, pale color, and vesicular (sponge-like, porous) texture. Commonly found near volcanic regions worldwide.
