Gabbro is a coarse-grained igneous rock primarily composed of plagioclase feldspar and pyroxene. It forms from the slow cooling of magma beneath the Earth's surface, resulting in its large crystal structure. Gabbro is often dark in color and is commonly found in oceanic crust and some continental regions. This rock is significant in geology as it helps scientists understand the processes of plate tectonics and the formation of oceanic crust. Gabbro is also used in construction and as a decorative stone due to its durability and attractive appearance.