igneous
Scoria (vesicular volcanic rock)
Scoria; basaltic to andesitic volcanic rock, chiefly plagioclase, pyroxene, and volcanic glass
AI-generated identification · may be incorrectDark brown, rough and highly vesicular, with no visible crystals; typically Mohs 5–6, dull to slightly glassy, and low in density. The cavities formed as gas bubbles in lava; individual mineral cleavage is not apparent.
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Physical properties
Dark brown, rough and highly vesicular, with no visible crystals; typically Mohs 5–6, dull to slightly glassy, and low in density. The cavities formed as gas bubbles in lava; individual mineral cleavage is not apparent.
Formation & geological history
Forms when gas-rich lava cools rapidly, commonly around cinder cones and other volcanic vents. Its age depends on the eruption; the specimen’s age cannot be determined from the image.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, and abrasive; attractive pieces are collected or used decoratively.
Geological facts
Scoria is generally denser and less frothy than pumice, and its vesicles are often larger and irregular.
Field identification & locations
Likely scoria based on its dark color and abundant open cavities; confirm by its volcanic texture and lightweight feel. Common near basaltic volcanoes and cinder cones worldwide.
