igneous
Likely vesicular basalt
Basalt, a fine-grained volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine
AI-generated identification · may be incorrectDark gray-green and rough, with small cavities (vesicles) visible on the other specimens in the box; the held piece is too blurred to confirm its texture. Basalt minerals are typically Mohs 5–6, with a dull to slightly vitreous luster and no prominent cleavage.
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Physical properties
Dark gray-green and rough, with small cavities (vesicles) visible on the other specimens in the box; the held piece is too blurred to confirm its texture. Basalt minerals are typically Mohs 5–6, with a dull to slightly vitreous luster and no prominent cleavage.
Formation & geological history
Forms when low-silica lava cools at or near the surface; basalt occurs from many geological ages, so age cannot be determined from this image.
Uses & applications
Used as crushed aggregate, road stone, and construction material; selected pieces are collected as volcanic specimens.
Geological facts
Vesicles form when gas bubbles are trapped as lava cools; the specimen shown may be basalt, but the image does not provide enough detail for a certain identification.
Field identification & locations
Check for a dense, fine-grained dark groundmass and confirm cavities or visible mineral grains; basalt is common in volcanic regions worldwide. A fresh, unweathered surface helps distinguish it from other dark rocks.
