igneous
Pumice
Pumice
Hardness: ~(5-6) but friable, Color: Light colored (white, gray, pale tan), Luster: Earthy, Crystal structure: Amorphous (glassy), Cleavage: None, Specific gravity: Low (floats on water)
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Physical properties
Hardness: ~(5-6) but friable, Color: Light colored (white, gray, pale tan), Luster: Earthy, Crystal structure: Amorphous (glassy), Cleavage: None, Specific gravity: Low (floats on water)
Formation & geological history
Formed during explosive volcanic eruptions when highly vesicular rough-textured volcanic glass is rapidly cooled and depressurized.
Uses & applications
Used in lightweight concrete, as an abrasive in polishes, pencil erasers, cosmetics, and for stonewashed jeans.
Geological facts
Pumice is the only rock that floats on water due to its highly porous nature.
Field identification & locations
Identify by its highly vesicular (full of holes) texture and its extreme light weight. Commonly found downwind or downstream from explosive volcanoes.
