Plagioclase is striped black-gray-white, pyroxene is colorful, there are some small olivine grains as well. Intrusive Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by way of pre-present rock (called us of a rock); the magma cools slowly and, as a result, these rocks are coarse-grained. It is often mentioned that the term “gabbro” was brought into geological terminology by a German geologist Leopold von Buch. The difference between the two rock types is their grain size. Gabbros are equivalent in composition to basalts. As the magma slowly cools, crystallization takes place; which minerals develop depends on the temperature reached. Tappeluft, Norway. Storås, Norway. Gabbro and granite are examples of intrusive igneous rocks. This is one type of extrusive igneous rock, but basalt and pumice also belong to this category, along with many others. Sometimes the term “gabbro” is used loosely to include them all. Width of sample 55 mm. Gabbro 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. Gabbro ( /ˈɡæbroʊ/) 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. Hornblende gabbro (metagabbro) with finer structure. Norite. Igneous rocks with similar composition are basalt (extrusive equivalent of gabbro) and diabase (the same rock type could be named dolerite or microgabbro instead). On the other hand, gabbro has more than 95% of its pyroxenes in the form of the monoclinic clinopyroxene/s. The term itself comes from Italy. Gabbroic rocks are usually equigranular (composed of similarly sized grains) mixtures of black, brown or greenish pyroxene and white, gray, or greenish plagioclase. Napp, Flakstadøya, the Lofoten Archipelago, Norway. In the stone industry size gabbro is sold under the name “black granite”. The feldspar is a basic plagioclase generally labradorite, but occasionally bytownite or anorthite. Gabbro is usually equigranular in texture, although it may be porphyritic at times, especially when plagioclase oikocrysts have grown earlier than the groundmass minerals. For instance, a dark-colored plutonic mafic rock, the deep version of basalt, is called gabbro. Leucocratic norite (orthopyroxene gabbro). The word \"basalt\" is used because the rocks of the oceanic crust have a \"basaltic\" composition. Volcanic rocks:Subvolcanic rocks:Plutonic rocks: Learn how and when to remove this template message, International Union of Geological Sciences, https://en.wikipedia.org/w/index.php?title=Gabbro&oldid=997929467, Short description is different from Wikidata, Articles needing additional references from March 2015, All articles needing additional references, Articles needing additional references from October 2019, Creative Commons Attribution-ShareAlike License, This page was last edited on 2 January 2021, at 22:59. Gabbro is an igneous rock which has crystallized deep in the Earth. peridotite. Occurrence of igneous rocks can be either intrusive (plutonic) or extrusive (volcanic). Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Hence, rock names like nepheline-bearing gabbro or olivine norite are possible. Granite and gabbro are examples of igneous rocks formed in this way. These rocks are not as widespread as granitoids, but they are definitely not rare. Chemical composition of an average gabbro? When magma (lava) rises to the surface cools quickly, it forms extrusive igneous rock. What do you actually mean? A sample from Tangen, Hedmark, Norway. It belongs to the intrusive igneous rock family. Basalt. Finer grained equivalents of gabbro are called diabase (also known as dolerite), although the term microgabbro is often used when extra descriptiveness is desired. This is how gabbro looks under the polarising microscope (crossed polars). Ødegården Verk, Norway. Gabbro is an example of intrusive igneous rock. Cpx ) basic and ultrabasic types, according to where its magma collected — than... And subsequent deep erosion but it is monoclinic pyroxene anyway ( either diopside or augite ) added... Also be present surface to cool as a mineral now, but occasionally or. 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