What is Gabbro?
[[File:GabbroRockCreek1.jpg|thumb|Gabbro specimen; Rock Creek Canyon, eastern [[Sierra Nevada (US)|Sierra Nevada]], California.]] [[File:Gabbro pmg ss 2006.jpg|thumb|A thin section of gabbro under the [[microscope]] shows the [[crystal]]s of which it is made.]] [[File:main ridge of the cuillin in skye arp.jpg|thumb|right|A gabbro landscape on the main ridge of the [[Cuillin]], [[Isle of Skye]], [[Scotland]].]] [[File:SierraXenolith.JPG|thumb|Gabbro as a [[xenolith]] ('foreign' rock) in a [[granite]], Sierra Nevada, Rock Creek Canyon, California.]] '''Gabbro''' is a large group of dark, coarse-grained, [[igneous rock]]s. They are chemically equivalent to [[basalt]]. The rocks are [[Intrusive|plutonic]], formed when molten [[magma]] is trapped under the [[Earth]]'s surface and cools into a [[crystal]]line mass. Most of the Earth's surface has gabbro in the [[oceanic crust]], produced by basalt [[magma]]tism at [[mid-ocean ridge]]s. In general, when the gabbro is formed, it lies above the [[Earth's mantle]], and below the basalt. Gabbro is generally coarse grained, with crystals in the size range of 1 mm or greater. It is an essential part of the [[oceanic crust]]. Long belts of gabbro intrusions<ref>Intrusion: pushed its way between other rocks</ref> are typically formed at proto-[[Rift (geology)|rift zone]]s and around ancient rift zone margins. == Notes == {{Reflist}} [[Category:Igneous rocks]]