igneous
Likely vesicular basalt (scoria-like fragment)
Basaltic volcanic rock; chiefly plagioclase, clinopyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectGray-green, porous, fine-grained fragment with dull to slightly vitreous luster; likely Mohs hardness 5–6, with no obvious cleavage and low-to-moderate specific gravity due to vesicles. The green coloration may reflect olivine or alteration minerals.
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Physical properties
Gray-green, porous, fine-grained fragment with dull to slightly vitreous luster; likely Mohs hardness 5–6, with no obvious cleavage and low-to-moderate specific gravity due to vesicles. The green coloration may reflect olivine or alteration minerals.
Formation & geological history
Formed when iron- and magnesium-rich lava cooled rapidly at or near Earth’s surface, trapping gas bubbles; age cannot be determined from the photograph. Common in volcanic flows, cinders, and scoria deposits.
Uses & applications
Used as aggregate, road material, lightweight landscaping stone, and occasionally as a teaching or collecting specimen; this small fragment has negligible commercial value.
Geological facts
Its vesicles are gas cavities, distinguishing it from most massive crystalline rocks. A magnet may show weak attraction if iron-bearing minerals are abundant.
Field identification & locations
Common worldwide in volcanic regions, including Hawaii, Iceland, the Cascades, Mexico, and Mediterranean volcanoes. Confirm with a fresh surface, hardness near 6, dark basaltic color, and lack of carbonate fizz; exact identification requires testing.
