igneous
Vesicular volcanic rock, likely pumice or scoria
Pumice/scoria; predominantly silica-rich volcanic glass with feldspar and possible quartz or mafic minerals
AI-generated identification · may be incorrectLight tan-gray, highly porous, matte to dull luster, and likely very low density; hardness is approximately 5–6 for glassy pumice, with no obvious cleavage. The dark streaks may be embedded lithic or iron-rich mineral fragments.
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Physical properties
Light tan-gray, highly porous, matte to dull luster, and likely very low density; hardness is approximately 5–6 for glassy pumice, with no obvious cleavage. The dark streaks may be embedded lithic or iron-rich mineral fragments.
Formation & geological history
Formed when gas-rich lava erupted explosively and rapidly cooled, trapping bubbles in volcanic glass; typically Quaternary to recent, though older deposits are common. Exact identification is limited by the photograph.
Uses & applications
Used as lightweight aggregate, abrasive, exfoliating material, filtration media, and landscaping stone; attractive pieces are collected but are generally low value.
Geological facts
Pumice commonly floats in water, while denser scoria usually sinks. Pale color favors pumice, whereas abundant dark, iron-rich material and greater density favor scoria.
Field identification & locations
Test density by placing it in water, inspect the vesicles, and check for a glassy fracture; a streak test is usually unhelpful. Common around explosive volcanic regions such as Italy, Iceland, the western United States, Japan, and New Zealand.
