Clash Royale CLAN TAG #URR8PPP A coarse-grained mafic intrusive rock Gabbro Photomicrograph of a thin section of gabbro Gabbro ( / ˈ ɡ æ b r oʊ / ) is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term "gabbro" may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic". Contents 1 Etymology 2 Petrology 3 Distribution 4 Uses 5 See also 6 References 7 External links Etymology The term "gabbro" was used in the 1760s to name a set of rock types that were found in the ophiolites of the Apenn