Gabbro is a dark, coarse-grained, gray to black igneous rock formed by the slow cooling of magma at depth, which allows the growth of large crystals. Composed mainly of plagioclase and pyroxene, it is the plutonic (formed in the interior) equivalent of basalt, and is found in the oceanic and continental crust, being widely used as construction aggregate, gravel, and in the ornamental stone and countertop industry.