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Gabbro specimen Photomicrograph of a thin section of gabbro. Gabbro (/ ˈ ɡ æ b r oʊ / GAB-roh) is a phaneritic (coarse-grained and magnesium- and iron-rich), mafic intrusive igneous rock formed from the slow cooling magma into a holocrystalline mass deep beneath the Earth's surface.
Diabase (/ ˈ d aɪ. ə ˌ b eɪ s /), also called dolerite (/ ˈ d ɒ l. ə ˌ r aɪ t /) or microgabbro, [1] is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained to aphanitic chilled margins which may ...
The cumulate rock is a plagioclase-pyroxene cumulate (a gabbro) and the melt is now more felsic and aluminous in composition (trending towards andesite compositions). In the above example, the plagioclase and pyroxene need not be pure end-member compositions (anorthite-enstatite), and thus the effect of depletion of elements can be complex.
Trap rock, also known as either trapp or trap, is any dark-colored, fine-grained, non-granitic intrusive or extrusive igneous rock. Types of trap rock include basalt, peridotite, diabase, and gabbro. [1] Trap is also used to refer to flood (plateau) basalts, such as the Deccan Traps and Siberian Traps. [2]
The Famrinto Gabbro has two gabbronorites that are slightly different in mineralogy and texture. [1] One rock type is a olivine, pyroxene, hornblende while the other has clinopyroxene, olivine, and plagioclase gabbronorite with cumulus texture. [1] The hornblende gabbronorite is a dark grey to grey-green with a fine to medium grained texture. [5]
Quartz gabbro is an intrusive rock with a composition intermediate between gabbro and tonalite.It is defined in the QAPF classification as coarse-grained igneous rock in which quartz makes up 5% to 20% of the QAPF mineral fraction, plagioclase makes up 90% or more of the total feldspar content, and the plagioclase is calcium-rich (%An > 50).
A rock peak 870 metres (2,850 ft) high located 3 nautical miles (5.6 km; 3.5 mi) east of Mount Justman in the northeast corner of Gabbro Hills, near the edge of the Ross Ice Shelf. Discovered and photographed by the Byrd Antarctic Expedition (1928-30) and named for Benjamin Roth, mechanic and U.S. Army representative on that expedition. [7]
Zuma Rock is a large natural monolith, or inselberg, an igneous intrusion composed of gabbro and granodiorite, located in Madalla, a town in Niger State, Nigeria. [1] It is situated in the west of Nigeria's capital, Abuja, along the main road from Abuja to Kaduna, off Madalla, and is sometimes referred to as the "Gateway to Abuja from Suleja". [2]