igneous
Weathered vesicular basalt (scoria-like volcanic rock)
Vesicular basalt; chiefly plagioclase, pyroxene, and iron oxides
AI-generated identification · may be incorrectCoarse, irregular specimen with reddish-brown weathering and dark rounded cavities/inclusions; basalt typically has Mohs hardness about 5–6, dull to subvitreous luster, and a fine-grained plagioclase–pyroxene structure. The image alone does not establish exact composition or density.
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Physical properties
Coarse, irregular specimen with reddish-brown weathering and dark rounded cavities/inclusions; basalt typically has Mohs hardness about 5–6, dull to subvitreous luster, and a fine-grained plagioclase–pyroxene structure. The image alone does not establish exact composition or density.
Formation & geological history
Formed when mafic lava cooled at or near the surface, with gas bubbles creating vesicles; the red-brown color likely reflects oxidation during weathering. Basalt forms in many geological periods, so age cannot be determined visually.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building stone; vesicular specimens are mainly collected or used decoratively.
Geological facts
The cavities may be gas vesicles, while the rusty colors commonly result from iron oxidation; some dark patches could also be mineral inclusions or weathering features.
Field identification & locations
Look for a dense, fine-grained dark matrix, scattered vesicles, and hardness sufficient to scratch glass; this sample’s weathered, mottled appearance is not diagnostic enough to confirm basalt without examination. Basalt is common in volcanic regions worldwide.
