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{{Short description|Achondritic stony meteorite}}
[[Image:IbitiraEucrite.jpg|thumb|175px|right|The Ibitira Eucrite, a non-cumulate non-[[breccia]]ted eucrite of the Stannern trend. New studies have shown that Ibitira is derived from a parent body other than 4 Vesta.<ref>{{cite journal
{{refimprove|date=July 2017}}
|author=Mittlefehldt, David W.
{{technical|date=July 2017}}
|title=Ibitira: A basaltic achondrite from a distinct parent asteroid and implications for the Dawn mission
{{Infobox meteorite subdivision
|journal=Meteoritics and Planetary Science
|Subdivision = Group
|volume=40/5
|Name = Eucrite
|pages=665–677
|Alternative_names =
|year=2005
|Image = Meteor Stonařov u Jihlavy.jpg
|doi=}}</ref> While it has the characteristics and minerology of a Eucrite it is not genetically related to the HED meteorites.]]
|Image_caption = Stannern eucrite, found in the Czech Republic.
⚫
[[Image:Eucrite_GRA98033.jpg|thumb|175px|right|QUE94200 a [[breccia]]ted eucrite about 5 [[centimeter|cm]] across, found in the Graves Nunataks region of Antarctica.]]
|Image_alt_text =
⚫
'''Eucrites''' are [[achondrite|achondritic]] stony [[meteorite]]s, many of which originate from the surface of the [[asteroid]] [[4 Vesta]] and as such are part of the [[HED meteorite]] group. They are the most common achondrite group with well over 100 distinct finds at present.
|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 [[breccia]]ted eucrite about 5 cm across, found in the Graves Nunataks region of Antarctica.
|Image2_alt_text =
}}
⚫
'''Eucrites''' are [[achondrite|achondritic]] stony [[meteorite]]s, 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 [[basalt]]ic rock from the [[crust]] of [[4 Vesta]] or a similar parent body. They are mostly composed of [[Calcium|Ca]]-poor [[pyroxene]], [[pigeonite]], and [[Calcium|Ca]]-rich [[plagioclase]] ([[anorthite]]). <ref>B. Mason: Meteorites. John Wiley, New York 1962.</ref>
Eucrites consist of [[basalt]]ic rock from the [[Crust (geology)|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>
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:
* '''Non-cumulate eucrites''' are the most common variety and can be subdivided further:
** '''Main series eucrites''' formed near the surface and are mostly, though not exclusively, [[regolith]] [[breccia]]s [[lithification|lithified]] under the pressure of overlying newer deposits.
** '''Main series eucrites''' formed near the surface and are mostly [[regolith]] [[breccia]]s [[lithification|lithified]] under the pressure of overlying newer deposits.
** '''Stannern trend eucrites''' are a rare variety.
** '''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.
** '''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|Vesta]]'s crust.
* '''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]] [[breccia]]s consisting of mostly eucrite fragments and less than one part in ten of [[diogenite]], an arbitrary dividing line from the [[howardite]]s, which are related in structure. They are comparably rare.
* '''Polymict eucrites''' are [[regolith]] [[breccia]]s 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 ''eukritos'' meaning "easily distinguished". This refers to the silicate minerals in them, which can be easily distinguished because of their relatively large grain size.
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 (geology)|crust]]. The term was used as a rock type name for some of the [[Paleogene]] igneous rocks of [[Geology of Scotland|Scotland]].<ref>Sutherland, D. S. (1982) ''Igneous Rocks of the British Isles'', Chichester, John Wiley, page 536.</ref>

==See also==
* [[Glossary of meteoritics]]
==References==
==References==
{{Reflist}}


== External links ==
<references/>
*[http://www.meteorites.com.au/collection/achondrites.html#Eucrites Eucrite images] - Meteorites Australia


{{Meteorites}}


[[Category:Planetary science]]
[[Category:Planetary science]]
[[Category:Meteorite types]]
[[Category:Asteroidal achondrites]]
[[Category:4 Vesta]]


[[it:Meteorite HED#Eucriti]]
[[simple:Eucrite]]
[[sl:Evkrit]]
[[it:Eucrite]]

Latest revision as of 20:39, 28 September 2022

Eucrite
— Group —
Stannern eucrite, found in the Czech Republic.
Compositional typeStony
TypAchondrite
ClassAsteroidal achondrite
ClanHED meteorite
Subgroups
  • Non-cumulate eucrites
    • Main series eucrites
    • Stannern trend eucrites
    • Nuevo Laredo trend eucrites
  • Cumulate eucrites
  • Polymict eucrites
Parent body4 Vesta and others
CompositionBasaltic rock, mostly Calcium-poor pyroxene, pigeonite, and Calcium-rich plagioclase (anorthite)
Total known specimens>100
GRA98033 a brecciated eucrite about 5 cm across, found in the Graves Nunataks region of Antarctica.

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).[1]

Based on differences of chemical composition and features of the component crystals, they are subdivided into several groups:[2]

  • 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

[edit]

Eucrites get their name from the Greek word 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.[3]

See also

[edit]

References

[edit]
  1. ^ B. Mason: Meteorites. John Wiley, New York 1962.
  2. ^ Mittlefehldt, McCoy, Goodrich and Kracher: Non-chondritic Meteorites from Asteroidal Bodies, In: Reviews in Mineralogy Vol. 36, Planetary Materials, Mineralogical Society of America, 1998.
  3. ^ Sutherland, D. S. (1982) Igneous Rocks of the British Isles, Chichester, John Wiley, page 536.
[edit]
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