igneous
Gabbro
Plagioclase-pyroxene intrusive igneous rock
Hardness of 6 on the Mohs scale, colors typically dark gray to black, submetallic or dull luster, coarse-grained phaneritic crystal structure, specific gravity around 2.7 to 3.3.
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Physical properties
Hardness of 6 on the Mohs scale, colors typically dark gray to black, submetallic or dull luster, coarse-grained phaneritic crystal structure, specific gravity around 2.7 to 3.3.
Formation & geological history
Formed from the slow cooling of magnesium- and iron-rich magma beneath the Earth's surface into a coarse-grained plutonic rock.
Uses & applications
Used in construction, as crushed stone for road bases, dimension stone for buildings and monuments, and polished for kitchen countertops.
Geological facts
Gabbro is the intrusive equivalent of basalt, meaning it has the same chemical composition but cooled slowly deep underground rather than erupting onto the surface.
Field identification & locations
Identify by its dark, speckled appearance containing visible crystals of dark pyroxene and lighter plagioclase feldspar. Commonly found in oceanic crust and layered intrusive complexes worldwide.
