igneous
Vesicular basalt (likely weathered basaltic lava)
Basalt; primarily plagioclase, clinopyroxene, and iron-rich olivine, with possible alteration minerals
AI-generated identification · may be incorrectDark reddish-brown, fine-grained, and weakly vesicular with rounded gas cavities; typically dull to subtly vitreous luster, no visible cleavage, hardness about 5–6, and specific gravity roughly 2.8–3.0.
Identified More igneous →
Explore Vesicular basalt (likely weathered basaltic lava) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark reddish-brown, fine-grained, and weakly vesicular with rounded gas cavities; typically dull to subtly vitreous luster, no visible cleavage, hardness about 5–6, and specific gravity roughly 2.8–3.0.
Formation & geological history
An extrusive igneous rock formed when mafic lava cooled rapidly at or near Earth’s surface; the reddish color commonly results from oxidation and weathering of iron-bearing minerals. Exact age and locality cannot be determined from the photograph.
Uses & applications
Used as crushed aggregate, roadstone, riprap, ballast, and occasionally decorative stone; attractive polished pieces may be collected but are generally low-value.
Geological facts
Vesicles formed from gas bubbles trapped during lava cooling, while oxidation can produce a rust-red surface. The specimen could also be an iron-rich volcanic rock such as scoria, but it appears relatively dense.
Field identification & locations
Identify by its dark fine-grained matrix, magnetic response in many specimens, irregular vesicles, and lack of obvious sedimentary layering or large crystals; common in volcanic regions worldwide, including Hawaii, Iceland, India, and the western United States.
