igneous
Vesicular volcanic rock (likely scoria)
Scoria, typically basaltic to andesitic volcanic rock
AI-generated identification · may be incorrectDark gray-brown, rough and highly porous, with rounded gas cavities (vesicles); chiefly fine-grained plagioclase, pyroxene, and sometimes olivine. Hardness varies, commonly about 5–6 Mohs; generally dull to slightly glassy, with no prominent cleavage. The photograph alone cannot confirm its exact composition.
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Physical properties
Dark gray-brown, rough and highly porous, with rounded gas cavities (vesicles); chiefly fine-grained plagioclase, pyroxene, and sometimes olivine. Hardness varies, commonly about 5–6 Mohs; generally dull to slightly glassy, with no prominent cleavage. The photograph alone cannot confirm its exact composition.
Formation & geological history
Forms when gas-rich lava cools quickly, trapping bubbles; most commonly associated with geologically recent volcanic eruptions. Similar pitted pieces can also form through other processes, so a definitive identification may require examination.
Uses & applications
Used as lightweight aggregate, drainage or landscaping stone, abrasive, and sometimes in decorative objects; porous specimens are collected as volcanic curiosities.
Geological facts
The holes are vesicles left by escaping or trapped gas. Scoria is generally denser and darker than pumice, though this specimen’s identity cannot be confirmed from appearance alone.
Field identification & locations
Look for a lightweight, dark, vesicular texture and volcanic mineral grains; scoria occurs near basaltic volcanoes and lava flows worldwide. Value depends on size, provenance, and appearance.
