igneous
Dark vesicular volcanic rock, likely basaltic scoria
Scoria (vesicular basalt; composition commonly plagioclase, pyroxene, and iron-rich glass)
AI-generated identification · may be incorrectDark gray to black, dull to slightly glassy, irregular and highly vesicular surface; typically hardness about 5–6 Mohs, no obvious cleavage, and specific gravity roughly 2.0–2.8 depending on porosity. The photograph is insufficient to confirm mineral grains or vesicles conclusively.
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Physical properties
Dark gray to black, dull to slightly glassy, irregular and highly vesicular surface; typically hardness about 5–6 Mohs, no obvious cleavage, and specific gravity roughly 2.0–2.8 depending on porosity. The photograph is insufficient to confirm mineral grains or vesicles conclusively.
Formation & geological history
Forms when gas-rich basaltic magma erupts and rapidly cools, trapping bubbles; it is generally geologically young in volcanic fields, ranging from recent eruptions to Quaternary age. It commonly occurs in cinder cones, lava flows, and volcanic bomb deposits.
Uses & applications
Used as lightweight aggregate, drainage material, landscaping stone, and sometimes abrasive or decorative rock; ordinary pieces have little jewelry value.
Geological facts
Scoria is denser and generally darker than pumice, while still containing abundant gas cavities. A magnet may show weak attraction if the rock contains appreciable magnetite.
Field identification & locations
Common around basaltic volcanoes, including Iceland, Hawaii, Mexico, East Africa, and many continental volcanic fields. Confirm by checking for lightweight porous texture, a streakless dark surface, and lack of uniform manufactured shape; the attached vegetation is not part of the specimen.
