igneous
Weathered basalt or volcanic scoria fragment
Basaltic volcanic rock; chiefly plagioclase, pyroxene, and iron-rich oxides
AI-generated identification · may be incorrectDark gray to brown, fine-grained and strongly weathered, with small vesicles and a dull earthy luster; typical hardness 5–6 Mohs, no visible cleavage, and specific gravity about 2.7–3.0.
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Physical properties
Dark gray to brown, fine-grained and strongly weathered, with small vesicles and a dull earthy luster; typical hardness 5–6 Mohs, no visible cleavage, and specific gravity about 2.7–3.0.
Formation & geological history
Likely formed when basaltic lava cooled rapidly at or near Earth’s surface, producing an aphanitic texture and possible gas cavities; its precise geological age cannot be determined from the image.
Uses & applications
Common basalt is used as crushed aggregate, road stone, concrete material, and occasionally dimension stone; this small weathered piece has mainly educational or souvenir value.
Geological facts
The orange-brown coating is probably oxidation of iron-bearing minerals, while the black areas may be fresher basalt or iron-rich alteration products.
Field identification & locations
Identify it by its very dark fine-grained interior, relatively high density, vesicles, and lack of obvious individual crystals; common worldwide in volcanic regions, especially oceanic islands and lava fields.
