Gabbro is a large group of dark, mafic igneous rocks that are chemically similar to basalt. Gabbro can also be gray or light green. Gabbro forms under similar conditions to granite and diorite. Slow cooling produces the large crystals. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass. It is an essential part of the oceanic crust . How was it formed? Bibliography Slow cooling produces the large crystals. QAPF Diagram Quartz Gabbro field in blue. Gabbro is the plutonic equivalent of basalt. Slow-cooling, coarse-grained gabbro is chemically equivalent to … But unlike granite, gabbro forms from magma that is rich in iron and magnesium, and poor in quartz (silica). Gabbro is a strange name that most people aren't familiar with, much less how it is formed. Gabbro is formed when magnesium and iron-rich magma cools slowly underground, so it is an igneous rock. Gabbro is sometimes called “black granite” for it too is coarse-grained, but a large proportion of iron-bearing minerals make gabbro heavier and dark colored. Gabbro is an essential part of the oceanic crust, and can be found in many ophiolite. Basalt is clearly the most common volcanic rock on Earth and basaltic rocks (including gabbro, diabase and their metamorphosed equivalents) are the most common rocks in the crust 2.Basalt is also common on the Moon and other rocky planets of the Solar System. How was it formed? Long belts of gabbroic intrusions are typically formed at proto-rift zones and around ancient rift zone margins, intruding into the rift flanks. Long belts of gabbro intrusions [1] are typically formed at proto- rift zones and around ancient rift zone margins. Gabbro can be formed as a massive, uniform intrusion via in-situ crystallisation of pyroxene and plagioclase, or as part of a layered intrusion as a cumulate formed by settling of pyroxene and plagioclase. Gabbro is a strange name that most people aren't familiar with, much less how it is formed. It covers an area of 4715 km 2. Gabbro is generally coarse grained, with crystals in the size range of 1 mm or greater. Gabbro forms under similar conditions to granite and diorite. Gabbro / ˈ ɡ æ b / refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. Cumulate gabbros are more properly termed pyroxene-plagioclase orthocumulate. Basalt is a major rock type that occurs in virtually every tectonic setting. From sandatlas.org. Gabbro forms deep within the Earth’s crust, often from very large masses of magma that do not reach the surface. Long belts of gabbroic intrusions are typically formed at proto-rift zones and around ancient rift zone margins, intruding into the rift flanks. Gabbro is a large group of dark, mafic igneous rocks that are chemically similar to basalt. Gabbro is mafic, intrusive, coarse-grained rock with allotriomorphic texture. Gabbro is an essential part of the oceanic crust, and can be found in many ophiolite complexes as parts of zones III and IV (sheeted dyke zone to massive gabbro zone). Gabbro is an essential part of the oceanic crust, and can be found in many ophiolite complexes as parts of zones III and IV (sheeted dyke zone to massive gabbro zone). Gabbro forms deep within the Earth’s crust, often from very large masses of magma that do not reach the surface. Gabbro Gabbro is a dense, mafic intrusive rock. Granite is an intrusive igneous rock, which means it was formed in place during the cooling of molten rock.Generally, the slower the molten rock cooled, the larger it’s mineral crystals with K-Feldspar megacrysts forming in special circumstances greater than 5cm. These intrusions formed a sill some 16 km thick, primarily of gabbro, but with significant amounts of anorthosite and other related granitic rocks. Gabbros contain mainly ferromagnesian minerals and plagioclase, the amount of ferromagnesian minerals equaling or exceeding that of the plagioclase. Gabbro is widely used as crushed stone for concrete aggregate, road base material, and railroad ballast. But unlike granite, gabbro forms from magma that is rich in iron and magnesium, and poor in quartz (silica). The Duluth Complex is one of the largest intrusions of gabbro on earth, and one of the largest layered mafic intrusions known. A gabbroid composed of 10-90% Ca-dominant plagioclase and >5% clinopyroxene.