igneous
Weathered volcanic rock, likely vesicular basalt
Basalt; primarily plagioclase feldspar, pyroxene, and iron oxides
AI-generated identification · may be incorrectGray, fine-grained, matte surface with small weathering pits or vesicles; hardness about 5–6 Mohs, typically massive with no visible cleavage, and specific gravity roughly 2.8–3.0.
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Physical properties
Gray, fine-grained, matte surface with small weathering pits or vesicles; hardness about 5–6 Mohs, typically massive with no visible cleavage, and specific gravity roughly 2.8–3.0.
Formation & geological history
Basalt forms when basaltic lava cools rapidly at or near Earth’s surface, commonly in volcanic flows; the specimen’s age cannot be determined from the image and may range from recent to billions of years.
Uses & applications
Used as aggregate, road stone, building material, and ballast; attractive polished pieces may be collected, though this example appears ordinary and unpolished.
Geological facts
Its rounded shape and pitted surface indicate prolonged water or abrasion weathering rather than a fresh angular fracture.
Field identification & locations
Common in volcanic regions, riverbeds, beaches, and glacial deposits. Confirm with a dark streak, lack of strong acid reaction, and microscopic crystals; a magnet may show weak attraction if iron-rich.
