Achondrite

Source: Wikipedia, the free encyclopedia.
Achondrite
— 
Stony
.

An achondrite

plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystallization on or within meteorite parent bodies.[4][5] As a result, achondrites have distinct textures and mineralogies indicative of igneous processes.[6]

Achondrites account for about 8% of meteorites overall, and the majority (about two-thirds) of them are HED meteorites, possibly originating from the crust of asteroid 4 Vesta. Other types include Martian, Lunar, and several types thought to originate from as-yet unidentified asteroids. These groups have been determined on the basis of e.g. the Fe/Mn chemical ratio and the 17O/18O oxygen isotope ratios, thought to be characteristic "fingerprints" for each parent body.[7]

Classification

Achondrites are classified into the following groups:[8]

Primitive achondrites

Primitive achondrites, also called PAC group, are so-called because their chemical composition is

chondrites, but their texture is igneous, indicative of melting processes. To this group belong:[8]

Asteroidal achondrites

Asteroidal achondrites, also called evolved achondrites, are so-called because they have been differentiated on a parent body. This means that their mineralogical and chemical composition was changed by melting and crystallization processes. They are divided into several groups:[8]

Lunar meteorites

Lunar meteorites are meteorites that originated from the Moon
.

Martian meteorite

Martian meteorites[10] are meteorites that originated from Mars. They are divided into three main groups, with two exceptions (see last two entries):

See also

References

  1. privative a) and the word chondrite
    .
  2. ^ Recommended classifications: Eucrite-pmict
  3. ^ Achondrite, Encyclopædia Britannica
  4. doi:10.1111/j.1945-5100.2007.tb00589.x
    .
  5. S2CID 129905814
    .
  6. ^ Mason, B. (1962). Meteorites. New York: John Wiley.
  7. ^ Mittlefehldt, David W.; McCoy, Timothy J.; Goodrich, Cyrena Anne; Kracher, Alfred (1998). "Non-chondritic Meteorites from Asteroidal Bodies". Reviews in Mineralogy and Geochemistry. 36 (1): 4.1–4.195.
  8. ^
    ISBN 0-521-62143-7
    .
  9. S2CID 128394153
    .
  10. doi:10.1016/S0032-0633(00)00105-7
    .

External links

Wikimedia Commons has media related to Achondrite meteorites.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Achondrite&oldid=1177660051"