igneous
Likely basalt or another dark, coarse-grained igneous rock
Possibly olivine-bearing basalt (plagioclase, pyroxene, and possibly olivine); identification is uncertain from the photo
AI-generated identification · may be incorrectThe small rough specimen is dark green-black with scattered lighter grains and a dull to slightly glassy surface. Basalt is typically Mohs 5–6, fine-grained, and lacks visible cleavage; this specimen’s exact texture and composition cannot be confirmed from the image.
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Physical properties
The small rough specimen is dark green-black with scattered lighter grains and a dull to slightly glassy surface. Basalt is typically Mohs 5–6, fine-grained, and lacks visible cleavage; this specimen’s exact texture and composition cannot be confirmed from the image.
Formation & geological history
Basalt forms when mafic lava cools at or near Earth’s surface; basaltic rocks occur from ancient volcanic terrains to recent eruptions. The specimen’s age and origin are unknown.
Uses & applications
Basalt is used as crushed aggregate, road stone, and building material; attractive or unusual pieces may be kept as collectibles.
Geological facts
The dark, speckled appearance is consistent with a mafic rock, but several rocks and minerals can look similar in a photograph.
Field identification & locations
Check for a dense, hard specimen with a fine-grained matrix and no layering; a streak, hardness, or close-up examination would help distinguish basalt from other dark rocks. Common worldwide in volcanic regions.
