igneous
Vesicular basalt (likely scoriaceous basalt)
Basalt, primarily plagioclase, pyroxene, and commonly olivine; vesicles may be lined with secondary minerals
AI-generated identification · may be incorrectDark gray-brown, fine-grained and matte to slightly vitreous, with abundant gas cavities; typically Mohs 5–6, no obvious cleavage, and specific gravity about 2.7–3.0. The pale blue-gray surface could indicate weathering or a thin coating/mineral infill.
Identified More igneous →
Explore 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-brown, fine-grained and matte to slightly vitreous, with abundant gas cavities; typically Mohs 5–6, no obvious cleavage, and specific gravity about 2.7–3.0. The pale blue-gray surface could indicate weathering or a thin coating/mineral infill.
Formation & geological history
Extrusive volcanic rock formed when basaltic lava cooled rapidly at or near the surface, trapping gas bubbles; commonly Cenozoic to modern, though basalt occurs throughout geologic time.
Uses & applications
Used as aggregate, roadstone, riprap, and landscaping rock; attractive vesicular pieces are collected, but this small specimen has little commercial gemstone value.
Geological facts
Vesicles distinguish scoria or vesicular basalt from dense basalt; reddish-brown spots commonly reflect iron oxidation. Identification is provisional because the image lacks a fresh broken surface and testing.
Field identification & locations
Common in volcanic regions such as Hawaii, Iceland, the Pacific Northwest, and mid-ocean ridges. Check for low density, hardness near glass, dark streak, and lack of fizz in dilute acid; metallic ore-like spots could warrant professional testing.
