igneous
Gabbro
Plagioclase-pyroxene intrusive igneous rock
Hardness of 6-7 on the Mohs scale, dark green, gray, or black color, dull to sub-vitreous luster, phaneritic (coarse-grained) crystal texture, specific gravity between 2.7 and 3.3.
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Physical properties
Hardness of 6-7 on the Mohs scale, dark green, gray, or black color, dull to sub-vitreous luster, phaneritic (coarse-grained) crystal texture, specific gravity between 2.7 and 3.3.
Formation & geological history
Formed from the slow cooling of magnesium- and iron-rich magma trapped beneath the Earth's surface, creating intrusive mafic rock equivalent in composition to extrusive basalt.
Uses & applications
Used in construction, dimension stone, flooring, facing stone, and sometimes sold as 'black granite' for monuments and countertops.
Geological facts
Gabbro makes up a large portion of the oceanic crust and is one of the most common rocks in the Earth's crust as a whole.
Field identification & locations
Identify in the field by its dark color, coarse-grained interlocking mineral crystals (mainly dark pyroxene and lighter plagioclase feldspar), and absence of quartz.
