igneous
Scoria (vesicular basalt)
Vesicular basalt, commonly called scoria; chiefly plagioclase, pyroxene, and iron-rich volcanic glass
AI-generated identification · may be incorrectDark gray-green, rough, and highly vesicular with a dull to slightly glassy luster; hardness about 5–6 Mohs. The cavities formed from gas bubbles, and the specimen may be relatively lightweight; crystal structure is fine-grained with no obvious cleavage.
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Physical properties
Dark gray-green, rough, and highly vesicular with a dull to slightly glassy luster; hardness about 5–6 Mohs. The cavities formed from gas bubbles, and the specimen may be relatively lightweight; crystal structure is fine-grained with no obvious cleavage.
Formation & geological history
Formed when gas-rich basaltic lava cooled rapidly, trapping bubbles as it solidified. It is generally geologically young volcanic material, though its age cannot be determined from the image.
Uses & applications
Used as lightweight aggregate, drainage and landscaping material, and in some abrasives; unusual pieces are collected as volcanic specimens.
Geological facts
Scoria is distinct from pumice, which is usually lighter-colored and so porous that it may float. The rounded holes are called vesicles.
Field identification & locations
Look for abundant rounded cavities, dark mafic color, and a rough volcanic texture; common near basaltic volcanoes and lava flows worldwide. The image does not establish its locality or exact composition.
