igneous
Vesicular basalt (dark volcanic rock)
Basalt, a fine-grained mafic volcanic rock; exact identification is uncertain from the image
AI-generated identification · may be incorrectDark gray to black, matte to slightly glassy, with scattered pale mineral grains and possible small vesicles. Typically Mohs hardness 5–6; composed mainly of plagioclase and pyroxene, often with olivine; crystals are too fine to distinguish easily.
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Physical properties
Dark gray to black, matte to slightly glassy, with scattered pale mineral grains and possible small vesicles. Typically Mohs hardness 5–6; composed mainly of plagioclase and pyroxene, often with olivine; crystals are too fine to distinguish easily.
Formation & geological history
Forms when iron- and magnesium-rich lava cools rapidly at or near Earth’s surface. Basalt occurs in volcanic settings ranging from recent flows to rocks billions of years old.
Uses & applications
Used as crushed aggregate, road stone, and building material; attractive pieces may be kept as display specimens.
Geological facts
Basalt is among Earth’s most widespread volcanic rocks and also forms much of the ocean floor.
Field identification & locations
Look for a dense, dark rock with fine grains; vesicles, if present, are rounded gas-bubble cavities. Common in volcanic regions and old lava flows; the image alone cannot confirm its composition.
