{{Short description|Achondritic stony meteorite}} {{refimprove|date=July 2017}} {{technical|date=July 2017}} {{Infobox meteorite subdivision |Subdivision = Group |Name = Eucrite |Alternative_names = |Image = Meteor Stonařov u Jihlavy.jpg |Image_caption = Stannern eucrite, found in the Czech Republic. |Image_alt_text = |Compositional_type = Stony |Type = Achondrite |Class = Asteroidal achondrite |Clan = HED meteorite |Group = <!-- list/link all subgroups of this group as a {{flatlist}} --> |Subgroups = {{Plainlist| *Non-cumulate eucrites **Main series eucrites **Stannern trend eucrites **Nuevo Laredo trend eucrites *Cumulate eucrites *Polymict eucrites }} |Structural_classification = |Parent_body = 4 Vesta and others |Composition = Basaltic rock, mostly Calcium-poor pyroxene, pigeonite, and Calcium-rich plagioclase (anorthite) |Petrologic_type = |Number_of_specimens = >100 |TKW = <!-- {{Convert||kg}} --> |Image2 = Eucrite GRA98033.jpg |Image2_caption = GRA98033 a brecciated eucrite about 5 cm across, found in the Graves Nunataks region of Antarctica. |Image2_alt_text = }} '''Eucrites''' are achondritic stony meteorites, many of which originate from the surface of the asteroid 4 Vesta and are part of the HED meteorite clan. They are the most common achondrite group with over 100 meteorites found.
Eucrites consist of basaltic rock from the crust of 4 Vesta or a similar parent body. They are mostly composed of calcium-poor pyroxene, pigeonite, and calcium-rich plagioclase (anorthite).<ref>B. Mason: Meteorites. John Wiley, New York 1962.</ref>
Based on differences of chemical composition and features of the component crystals, they are subdivided into several groups:<ref>Mittlefehldt, McCoy, Goodrich and Kracher: Non-chondritic Meteorites from Asteroidal Bodies, In: Reviews in Mineralogy Vol. 36, Planetary Materials, Mineralogical Society of America, 1998.</ref> * '''Non-cumulate eucrites''' are the most common variety and can be subdivided further: ** '''Main series eucrites''' formed near the surface and are mostly regolith breccias lithified under the pressure of overlying newer deposits. ** '''Stannern trend eucrites''' are a rare variety. ** '''Nuevo Laredo trend eucrites''' are thought to come from deeper layers of 4 Vesta's crust, and are a transition group towards the cumulate eucrites. * '''Cumulate eucrites''' are rare types with oriented crystals, thought to have solidified in magma chambers deep within 4 Vesta's crust. * '''Polymict eucrites''' are regolith breccias consisting of mostly eucrite fragments and less than one part in ten of diogenite. They are less common.
==Etymology== Eucrites get their name from the Greek word {{Lang|grc|eukritos}} meaning "easily distinguished". This refers to the silicate minerals in them, which can be easily distinguished because of their relatively large grain size.
Eucrite is also a now obsolete term for bytownite-gabbro, an igneous rock formed in the Earth's crust. The term was used as a rock type name for some of the Paleogene igneous rocks of Scotland.<ref>Sutherland, D. S. (1982) ''Igneous Rocks of the British Isles'', Chichester, John Wiley, page 536.</ref>
==See also== * Glossary of meteoritics ==References== {{Reflist}}
== External links == *[http://www.meteorites.com.au/collection/achondrites.html#Eucrites Eucrite images] - Meteorites Australia
{{Meteorites}}
Category:Planetary science Category:Asteroidal achondrites Category:4 Vesta