igneous
Gabbro
Phaneritic mafic intrusive igneous rock
Hardness of 6 on the Mohs scale, dark green to black or dark gray color, submetallic to vitreous 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, dark green to black or dark gray color, submetallic to vitreous 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, resulting in a coarse-grained intrusive rock equivalent to extrusive basalt.
Uses & applications
Used in construction, as crushed stone for road bases, dimension stone, building facades, and polished for kitchen countertops under trade names like 'black granite'.
Geological facts
Gabbro is the most abundant rock type in the oceanic crust and is also found in major continental layered intrusions such as the Bushveld complex in South Africa.
Field identification & locations
Identify in the field by its dark color and visible interlocking crystals of plagioclase feldspar and pyroxene. Commonly found in ophiolite complexes and large layered intrusions worldwide.
