igneous
Possible weathered basalt or iron-rich slag
Basalt, tentatively; composition likely plagioclase and pyroxene with possible magnetite
AI-generated identification · may be incorrectDark gray-green, fine-grained, dull to weakly metallic surface with pale mineral grains and vesicular/weathered texture; likely Mohs 5–6, with no obvious cleavage. The rounded shape and crust could also indicate industrial slag, which would reduce confidence in a natural-rock identification.
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Physical properties
Dark gray-green, fine-grained, dull to weakly metallic surface with pale mineral grains and vesicular/weathered texture; likely Mohs 5–6, with no obvious cleavage. The rounded shape and crust could also indicate industrial slag, which would reduce confidence in a natural-rock identification.
Formation & geological history
If basalt, it formed from rapidly cooled mafic lava, commonly during volcanic eruptions, at any geological age. Its strongly weathered, possibly magnetic appearance is also consistent with iron-rich volcanic rock or furnace slag.
Uses & applications
Basalt is used as aggregate, road stone, building stone, and occasionally in decorative work; an ordinary fragment has negligible commercial value.
Geological facts
The image alone cannot reliably distinguish basalt from slag, scoria, or a dark metamorphic rock. A magnet test, streak test, fresh-break examination, and density measurement would improve identification.
Field identification & locations
Common basalt occurs in volcanic regions and oceanic crust worldwide; look for fine grain, interlocking crystals, vesicles, and a dark streak. Strong attraction to a magnet, abundant glassy material, bubbles, or a melted-looking skin suggests slag rather than a natural specimen.
