igneous
Rounded volcanic boulder, likely basalt
Basalt (fine-grained mafic volcanic rock; identification is provisional from the image)
AI-generated identification · may be incorrectDark gray-brown, dull, fine-grained, and rounded; likely composed mainly of plagioclase and pyroxene, with possible olivine. Typical basalt hardness is about 6 on the Mohs scale; individual crystals are too small to identify here.
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Physical properties
Dark gray-brown, dull, fine-grained, and rounded; likely composed mainly of plagioclase and pyroxene, with possible olivine. Typical basalt hardness is about 6 on the Mohs scale; individual crystals are too small to identify here.
Formation & geological history
Formed when iron- and magnesium-rich lava cooled at or near Earth’s surface. Its age and exact formation environment cannot be determined from appearance alone.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, paving, and landscaping material; this boulder appears suited to garden decoration.
Geological facts
Basalt is among Earth’s most common volcanic rocks and also forms much of the ocean floor.
Field identification & locations
A dark, dense appearance and fine texture are consistent with basalt, but the image alone cannot confirm the rock type; check a fresh surface for fine grains and test hardness. Basalt occurs worldwide, especially in volcanic regions.
