igneous
Dark, coarse-grained rock (likely gabbro)
Gabbro, a mafic intrusive igneous rock
AI-generated identification · may be incorrectDark gray to black with visible interlocking grains and a granular luster; typically composed of plagioclase feldspar and pyroxene, sometimes olivine. Hardness is about 6–7 Mohs; exact minerals and properties cannot be confirmed from the image alone.
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Physical properties
Dark gray to black with visible interlocking grains and a granular luster; typically composed of plagioclase feldspar and pyroxene, sometimes olivine. Hardness is about 6–7 Mohs; exact minerals and properties cannot be confirmed from the image alone.
Formation & geological history
Forms when mafic magma cools slowly underground, allowing crystals to grow; gabbros occur in oceanic crust and other ancient intrusive bodies. The specimen’s age and origin cannot be determined visually.
Uses & applications
Used as crushed stone, aggregate, dimension stone, and occasionally for decorative or polished surfaces.
Geological facts
Gabbro is the coarse-grained intrusive equivalent of basalt; its visible crystals reflect slower cooling at depth.
Field identification & locations
Look for dark color and interlocking crystals, especially light plagioclase grains among darker minerals. Common in oceanic crust and mafic intrusions; the image is insufficient for a definitive identification.
