igneous
Likely basaltic rock (vesicular basalt/scoria)
Basalt, chiefly plagioclase feldspar, clinopyroxene, and iron-rich minerals; possible vesicular scoria
AI-generated identification · may be incorrectDark gray to black, fine-grained, dull to weakly glassy luster, irregular fracture, and small cavities/vesicles; typical hardness about 5–6 Mohs and specific gravity roughly 2.7–3.1. The reddish-brown areas may be iron-oxide weathering.
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Physical properties
Dark gray to black, fine-grained, dull to weakly glassy luster, irregular fracture, and small cavities/vesicles; typical hardness about 5–6 Mohs and specific gravity roughly 2.7–3.1. The reddish-brown areas may be iron-oxide weathering.
Formation & geological history
An extrusive volcanic rock formed when basaltic lava cooled rapidly at or near the surface; vesicles formed from escaping gas. Its exact geological age and locality cannot be determined from the photograph.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, riprap, and building stone; attractive pieces may be collected or used ornamentally. This specimen does not appear gem-quality.
Geological facts
Basalt is the most abundant volcanic rock on Earth and forms much of the oceanic crust. Vesicular basalt is lighter and more porous than massive basalt.
Field identification & locations
Identify it by its dark color, fine texture, volcanic cavities, and lack of obvious individual crystals; a streak, density, magnetism, and fresh-break examination would improve confidence. Common worldwide, especially in volcanic regions.
