igneous
Vesicular volcanic rock, likely pumice or scoria
Pumice/scoria; predominantly vesicular volcanic glass and feldspar-rich silicate minerals
AI-generated identification · may be incorrectLight tan, highly porous, matte to dull luster, with abundant rounded vesicles; typically hardness 5–6, no visible cleavage, and low density. The pale color favors pumice, though weathering or mineral staining may obscure the distinction from light scoria.
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Physical properties
Light tan, highly porous, matte to dull luster, with abundant rounded vesicles; typically hardness 5–6, no visible cleavage, and low density. The pale color favors pumice, though weathering or mineral staining may obscure the distinction from light scoria.
Formation & geological history
Forms when gas-rich lava rapidly decompresses and cools during an explosive eruption, trapping bubbles in the solidifying melt. It is generally geologically young and may occur in volcanic ash, tuff, or lava-flow deposits.
Uses & applications
Used as an abrasive, lightweight aggregate, soil amendment, filtration medium, and horticultural substrate; attractive pieces may be collected but are rarely used as gemstones.
Geological facts
Pumice can float when its interconnected pores exceed the density of water; scoria is usually darker, denser, and has larger, more irregular vesicles. The specimen’s rounded shape may reflect transport or tumbling.
Field identification & locations
Identify by its very low weight, abundant pores, glassy fractured surfaces, and lack of sedimentary layering; a streak test is usually white or absent. Common worldwide near explosive volcanic fields, including Italy, Iceland, Japan, Mexico, and the western United States.
