gabbro

1. (petrology) Originally, a kind of serpentine; now generally a coarsely crystalline, igneous rock consisting of lamellar pyroxene and labradorite.Examples: "It is known as gabbro and is thought to form the lower layer of the oceanic crust at about four kilometres depth and to comprise a layer up to six kilometres thick, making it one of the most abundant, if least recognisable, materials on earth."; "Against the dark Ordovician gabbro, the black volcanic base, Rhynie is a streak of technicolour."countableuncountable