igneous
Vesicular volcanic rock, likely pumice
Pumice; highly vesicular volcanic glass, commonly rhyolitic to dacitic in composition
AI-generated identification · may be incorrectUsually very light, pale gray to cream, and frothy with abundant interconnected cavities; hardness about 5–6, glassy to dull luster, no cleavage, and low specific gravity, often floating in water. The specimen’s rounded, porous appearance may also reflect abrasion or weathering.
Identified More igneous →
Explore Vesicular volcanic rock, likely pumice in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Usually very light, pale gray to cream, and frothy with abundant interconnected cavities; hardness about 5–6, glassy to dull luster, no cleavage, and low specific gravity, often floating in water. The specimen’s rounded, porous appearance may also reflect abrasion or weathering.
Formation & geological history
Forms when gas-rich felsic magma erupts explosively and rapidly cools, trapping bubbles in volcanic glass; ages range from recent eruptions to ancient deposits. Common around volcanic arcs, calderas, and ash-fall or pyroclastic-flow deposits.
Uses & applications
Used as an abrasive, lightweight aggregate, concrete additive, horticultural soil amendment, and cosmetic exfoliant; attractive pieces are collected but rarely gem-grade.
Geological facts
Pumice is distinguished from scoria by its generally pale color and finer, more abundant vesicles; scoria is typically dark red or black and denser. The image could alternatively show weathered vesicular basalt or a porous fossil fragment.
Field identification & locations
Field tests include very low density, scratchable glassy walls, and often buoyancy; inspect for consistent volcanic texture rather than shell-like layering. Common localities include Italy, Iceland, Japan, Turkey, the western United States, and New Zealand.
