igneous
Weathered volcanic rock, likely vesicular basalt or scoria
Basaltic volcanic rock; predominantly plagioclase, pyroxene, and possibly olivine with iron-oxide weathering
AI-generated identification · may be incorrectTypically Mohs 5–6, dark gray to reddish-brown, dull to weakly vitreous, fine-grained, and locally vesicular. The reddish coloration indicates oxidation; the gray, dense portion is consistent with basalt.
Identified More igneous →
Explore Weathered volcanic rock, likely vesicular basalt or scoria in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically Mohs 5–6, dark gray to reddish-brown, dull to weakly vitreous, fine-grained, and locally vesicular. The reddish coloration indicates oxidation; the gray, dense portion is consistent with basalt.
Formation & geological history
Formed when basaltic lava cooled rapidly at or near Earth’s surface, likely during a relatively young volcanic episode; weathering produced the iron-rich red coating. Exact age and locality cannot be determined from the photograph.
Uses & applications
Common basalt is used as aggregate, roadstone, riprap, and building stone; attractive vesicular pieces are mainly collected as geological specimens.
Geological facts
Vesicles are gas bubbles trapped in cooling lava, while the dense gray area represents less-gas-rich material. Scoria is generally lighter and more porous than ordinary basalt.
Field identification & locations
Look for a fine-grained dark matrix, irregular vesicles, reddish iron staining, and no obvious sedimentary layering or metamorphic banding. Common in volcanic regions such as Hawaii, Iceland, the Cascades, and continental basalt fields.
