igneous
Iron-rich vesicular rock, possibly slag or basalt
Uncertain; likely basaltic rock (plagioclase–pyroxene–iron oxide) or industrial iron slag
AI-generated identification · may be incorrectDark brown-gray, fine-grained and irregular, with small pale inclusions and possible vesicles; likely dull to weakly metallic. Estimated hardness about 5–6 if basalt, with moderate-to-high density; no visible cleavage or crystal faces.
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Physical properties
Dark brown-gray, fine-grained and irregular, with small pale inclusions and possible vesicles; likely dull to weakly metallic. Estimated hardness about 5–6 if basalt, with moderate-to-high density; no visible cleavage or crystal faces.
Formation & geological history
If natural, basalt formed from rapidly cooled mafic lava, commonly during volcanic activity from the Cenozoic onward. Its rounded, porous appearance could instead indicate human-produced furnace slag, which is not a natural rock.
Uses & applications
Basalt is used as aggregate, road stone, and building material; slag has limited industrial or decorative use. This small specimen has little jewelry value.
Geological facts
The image alone cannot reliably distinguish basalt from iron slag. A strong magnet, unusually glassy surfaces, metallic beads, or abundant bubbles would favor slag.
Field identification & locations
Common basalt occurs in volcanic regions and quarries worldwide; slag is found near historic furnaces, mines, and industrial sites. Test magnetism, streak, density, and a fresh surface; avoid destructive testing without permission.
