igneous
Likely vesicular basalt (scoria-like pebble)
Basalt; predominantly plagioclase, pyroxene, and possibly olivine
AI-generated identification · may be incorrectDark reddish-brown, fine-grained, dull to slightly earthy luster, with numerous small gas vesicles; hardness about 5–6 Mohs, no obvious cleavage, and typically specific gravity around 2.7–3.0 (lower if highly vesicular).
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Physical properties
Dark reddish-brown, fine-grained, dull to slightly earthy luster, with numerous small gas vesicles; hardness about 5–6 Mohs, no obvious cleavage, and typically specific gravity around 2.7–3.0 (lower if highly vesicular).
Formation & geological history
An extrusive volcanic rock formed when fluid basaltic lava cooled rapidly, trapping bubbles; commonly Cenozoic to recent, though basalt occurs throughout geological time.
Uses & applications
Used as aggregate, roadstone, landscaping rock, and occasionally as a decorative or lapidary material; ordinary pebbles have little commercial value.
Geological facts
The reddish coloration usually reflects oxidation of iron-bearing minerals. Its pores distinguish it from most dense basalt and may indicate scoria if the specimen is notably lightweight.
Field identification & locations
Identify it by its dark mafic color, fine texture, iron staining, and vesicles; common in volcanic regions, lava flows, and beaches derived from basalt. The image alone cannot exclude weathered scoria or another vesicular volcanic rock.
