igneous
Pumice
Pumice (Vesicular Felsic Igneous Rock)
Hardness: 6 on the Mohs scale; Color: Light gray, white, yellowish, or brownish; Luster: Dull to earthy; Crystal structure: Amorphous (glassy volcanic rock, often with microscopic crystallites); Specific gravity: Less than 1 (it floats on water due to high porosity).
- Hardness
- 6 on the Mohs scale
- Color
- Light gray, white, yellowish, or brownish
- Luster
- Dull to earthy
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Physical properties
Hardness: 6 on the Mohs scale; Color: Light gray, white, yellowish, or brownish; Luster: Dull to earthy; Crystal structure: Amorphous (glassy volcanic rock, often with microscopic crystallites); Specific gravity: Less than 1 (it floats on water due to high porosity).
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich felsic lava cools rapidly, causing dissolved gases to bubble out and become trapped as the lava solidifies into a foam-like glass.
Uses & applications
Used in lightweight concrete, abrasive cleaning stones (pumice stones), landscaping, horticulture as a soil conditioner, and in personal care products like exfoliating cosmetics.
Geological facts
Pumice is one of the very few geological specimens that can float on water. When large underwater volcanoes erupt, they can create massive 'pumice rafts' that drift across oceans for months.
Field identification & locations
Easily identified by its extremely low density, light weight, and characteristic vesicular (bory/holey) texture. Commonly found in regions with recent or historic explosive volcanic activity, such as around the Pacific Ring of Fire.
