igneous
Polished vesicular basalt (likely scoriaceous basalt)
Basalt, aphanitic mafic volcanic rock; chiefly plagioclase, pyroxene, and iron-rich oxides
AI-generated identification · may be incorrectDark gray to brown, locally metallic-looking and glossy from polishing, with abundant rounded vesicles and small pale mineral-filled cavities; hardness about 5–6 Mohs, fine-grained with no visible cleavage, and specific gravity roughly 2.8–3.1.
Identified More igneous →
Explore Polished vesicular basalt (likely scoriaceous basalt) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray to brown, locally metallic-looking and glossy from polishing, with abundant rounded vesicles and small pale mineral-filled cavities; hardness about 5–6 Mohs, fine-grained with no visible cleavage, and specific gravity roughly 2.8–3.1.
Formation & geological history
Formed when low-silica lava cooled rapidly at or near Earth’s surface, trapping gas bubbles; the exact geological age cannot be determined from the photograph. Some cavities appear secondarily filled by minerals such as quartz, calcite, or zeolites.
Uses & applications
Used as aggregate, road stone, riprap, and decorative landscape or polished stone; quality polished pieces are mainly collected for their unusual vesicular patterns.
Geological facts
The specimen’s rounded, highly polished shape and glossy surface indicate human processing. It is not identifiable as a meteorite from appearance alone; vesicles strongly favor terrestrial volcanic rock.
Field identification & locations
Identify by its very dark fine-grained matrix, high density, vesicles, and lack of metallic magnetic fusion crust; common worldwide in lava fields, especially oceanic volcanic regions. Approximate value: $5–$30 for a common polished specimen, potentially $30–$100 for unusually attractive material.
