igneous
Weathered volcanic rock, likely vesicular basalt or scoria
Basaltic scoria/vesicular basalt; exact identification requires fresh-surface and mineral tests
AI-generated identification · may be incorrectDark reddish-brown, strongly weathered, with abundant cavities and pale green-yellow alteration minerals, possibly zeolites, calcite, or clay. Basalt typically contains plagioclase, pyroxene, and olivine; hardness about 5–6, dull to earthy luster, fine-grained groundmass, and no obvious cleavage.
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Physical properties
Dark reddish-brown, strongly weathered, with abundant cavities and pale green-yellow alteration minerals, possibly zeolites, calcite, or clay. Basalt typically contains plagioclase, pyroxene, and olivine; hardness about 5–6, dull to earthy luster, fine-grained groundmass, and no obvious cleavage.
Formation & geological history
Formed from rapidly cooled basaltic lava, with gas bubbles producing vesicles; later groundwater weathering filled or coated cavities with secondary minerals. Likely Cenozoic or younger, though age cannot be determined from the image.
Uses & applications
Used as lightweight aggregate, landscaping stone, road material, and occasionally as a decorative or collector specimen; quality zeolite-filled pieces may be sold as minerals.
Geological facts
The pale material may represent amygdules—vesicles later filled by minerals—rather than original rock components. Color and texture can change substantially through oxidation and tropical weathering.
Field identification & locations
Look for a dark fine-grained matrix, low density, vesicles, and weak attraction to a magnet if magnetite is present; a glassy surface would favor scoria. Common in volcanic regions worldwide, including Hawaii, Iceland, India, and the Mediterranean.
