igneous
Scoria (vesicular volcanic rock)
Basaltic to andesitic scoria; chiefly plagioclase, pyroxene, and volcanic glass
AI-generated identification · may be incorrectDark gray to reddish-brown, rough and highly vesicular, with a glassy to dull luster; typically Mohs 5–6. The specimen appears small and weathered; exact mineralogy cannot be determined from the image alone.
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Physical properties
Dark gray to reddish-brown, rough and highly vesicular, with a glassy to dull luster; typically Mohs 5–6. The specimen appears small and weathered; exact mineralogy cannot be determined from the image alone.
Formation & geological history
Forms when gas-rich lava cools rapidly, trapping bubbles. Scoria is commonly Quaternary or younger, though it occurs in volcanic deposits of many ages.
Uses & applications
Used as lightweight aggregate, drainage material, landscaping stone, and abrasive; attractive pieces may be collected.
Geological facts
The holes are gas-bubble cavities (vesicles), and scoria is generally denser and less frothy than pumice.
Field identification & locations
Look for abundant rounded or elongated cavities and reddish or dark volcanic material; common around cinder cones and basaltic volcanic fields worldwide. The pictured piece may be a fragment, so field context would help confirm identification.
