igneous
Vesicular basalt (likely weathered volcanic scoria)
Basalt; chiefly plagioclase, clinopyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectDark gray to brown, strongly vesicular, weathered surface with abundant rounded cavities; typically matte to dull luster, fine-grained groundmass, no prominent cleavage, Mohs hardness about 5–6, and specific gravity roughly 2.7–3.0. The holes are gas vesicles, some enlarged by weathering or mineral dissolution.
Identified More igneous →
Explore Vesicular basalt (likely weathered volcanic scoria) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray to brown, strongly vesicular, weathered surface with abundant rounded cavities; typically matte to dull luster, fine-grained groundmass, no prominent cleavage, Mohs hardness about 5–6, and specific gravity roughly 2.7–3.0. The holes are gas vesicles, some enlarged by weathering or mineral dissolution.
Formation & geological history
An extrusive mafic igneous rock formed when gas-rich basaltic lava cooled rapidly at or near the surface. It commonly formed during relatively young volcanic eruptions, from the Cenozoic to Recent, though basalt occurs throughout geologic time.
Uses & applications
Used as lightweight aggregate, road material, drainage stone, landscaping rock, and occasionally as a decorative or sculptural stone; generally limited jewelry value.
Geological facts
Its high porosity indicates volatile-rich lava, commonly called scoria when the rock is especially vesicular. The pale green patches may represent weathering products such as chlorite, epidote, or other secondary minerals.
Field identification & locations
Identify it by its mafic gray-black color, abundant irregular vesicles, fine texture, and relatively heavy feel compared with pumice. Common around volcanic fields, lava flows, cinder cones, and oceanic islands.
