igneous
Vesicular basalt (scoriaceous basalt) with secondary minerals
Basalt, predominantly plagioclase–pyroxene–olivine; surface cavities may contain zeolites or calcite
AI-generated identification · may be incorrectDark gray to black, highly vesicular, rough and locally glassy, with possible small pale crystals lining cavities. Typical hardness is about 5–6 Mohs; no consistent cleavage; fine-grained crystal structure; specific gravity commonly 2.6–3.0, reduced by vesicles.
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Physical properties
Dark gray to black, highly vesicular, rough and locally glassy, with possible small pale crystals lining cavities. Typical hardness is about 5–6 Mohs; no consistent cleavage; fine-grained crystal structure; specific gravity commonly 2.6–3.0, reduced by vesicles.
Formation & geological history
An extrusive volcanic rock formed when basaltic lava cooled rapidly at or near the surface, trapping gas bubbles; likely Quaternary to recent where associated with young volcanic flows or scoria cones. Pale cavity fillings formed later from circulating mineral-rich fluids.
Uses & applications
Used as lightweight aggregate, landscaping stone, road material, and occasionally as a display specimen; cavity minerals can add modest collector interest.
Geological facts
The specimen appears more like vesicular basalt than metallic meteorite: its irregular vesicles, dull dark matrix, and gray mineral surfaces are characteristic of volcanic rock.
Field identification & locations
Identify by low density relative to massive basalt, abundant irregular holes, dark fine-grained matrix, and weak attraction or no attraction to a magnet; common in volcanic regions worldwide, including Hawaii, Iceland, Mexico, and the western United States.
