Anorthosite. Anorthite belongs to the Plagioclase Feldspar group, an isomorphous solid solution series. The other end member, Anorthite, contains calcium and no sodium. View a second image of Anorthosite 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. The term anorthosite, from Frenc anorthose (term for plagioclase) was coined by Sterry Hunt. • Archean anorthosite are formed during the Archean era and are charaterised by Calsic Plagioclase. Whether occurring on the Earth or on the Moon, anorthosite is formed by the crystallization of plagioclase feldspar from a cooling body of molten magma. At 1 atmosphere, anorthite melts at 1553 °C.. Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite, NaAlSi 3 O 8.Anorthite also refers to plagioclase compositions with more than 90 molecular percent of the anorthite endmember. Found on both the moon and the Earth, anorthosite is an igneous rock primarily comprised of plagioclase feldspars. The origin of some types of anorthosite is readily explained. Similar in composition to rocks on the moon, anorthosite is a coarse-grained, intrusive igneous rock composed almost entirely of a single mineral—plagioclase feldspar. Anorthosites in the Bushveld or Stillwater Complexes are cumulates that formed in layers in the upper parts of these large, differentiated mafic-ultramafic intrusions (Cawthorn, 1996). Albite is one end member, containing sodium and no calcium. Occurrence. If anorthosite could form quickly on planetesimals and magma oceans were common in the first few million years of the solar system, where are the anorthosites in the meteorite record? 19. In Minnesota, anorthosite was intruded into the lowermost lava flows that formed during the opening of the Midcontinent Rift. This is the result of tiny Fe-Ti oxide inclusions in plagioclase crystals that give them bluish-black hue. Lunar anorthosite is important in investigation of mars, venus and meteorites.They also have gem rock quality. The Qaqortorsuaq anorthosite occurrence was calculated to be 3 to 4 cubic km in size with 27 Mt of indicated and 32 Mt of inferred resources . Anorthosite and Gabbro Formation. According to the formation, all rocks are divided into :Igneous Rocks, Fossil Rocks and Metamorphic Rocks.Igneous rocks form by crystallization of magma or lava. It is a special form of iridescence. Anorthosite Anorthosite: Anorthosite: A leucocratic coarse-grained plutonic rock consisting essentially of plagioclase (usually labradorite or bytownite) often with small amounts of pyroxene. The reason for the absence of anorthositic crusts on achondrite parent bodies probably lies in their thermal and chemical evolution. Anorthite is a rare compositional variety of plagioclase. The name of the rock stems from the Greek an and orthos, which together mean “not upright,” a reference to the slanting form of the plagioclase crystals it contains. Anorthosite. The anorthosite occurs as a scull-cap on the mountain north of the borderland between the two pre-Cambrian complexes, the late 1.9 Ga old Nagssugtoqidian orogen, and the early Kangamiut complex. Anorthosite in many cases is not light-colored at all. Formation of rocks is a long process and hence, Anorthosite and Gabbro formation sounds very interesting. 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