igneous
Pumice
Pumice, vesicular volcanic glass (typically silica-rich rhyolitic composition)
AI-generated identification · may be incorrectLight gray to cream, highly porous and rough, with abundant gas bubbles; mostly glassy/amorphous, Mohs hardness about 5–6, and low specific gravity. The image’s porous texture is consistent with pumice, though appearance alone cannot confirm it.
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Physical properties
Light gray to cream, highly porous and rough, with abundant gas bubbles; mostly glassy/amorphous, Mohs hardness about 5–6, and low specific gravity. The image’s porous texture is consistent with pumice, though appearance alone cannot confirm it.
Formation & geological history
Forms when gas-rich lava cools and depressurizes rapidly during explosive eruptions, trapping bubbles in volcanic glass. It can form at many geological ages and is commonly associated with young volcanic deposits.
Uses & applications
Used as an abrasive, lightweight aggregate, soil conditioner, and in polishing and personal-care products; attractive pieces are collected but are rarely valuable.
Geological facts
Some pumice is buoyant enough to float until waterlogged; large floating rafts can form after eruptions.
Field identification & locations
Look for a lightweight, frothy stone with interconnected vesicles and a gritty feel; common near volcanoes and in ash-flow or beach deposits derived from volcanic regions. Similar porous rocks, especially scoria or coral, can be confused with it.
