Editing Meteorite (section)

== Classification ==
{{Main|Meteorite classification}}
{{multiple image
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 |image1=Murnpeowie meteorite.jpg
 |image2=Meteorito Marília.jpg
 |image3=Pallasite-Esquel-RoyalOntarioMuseum-Jan18-09.jpg
 |image4=10499 - Detailed Slice.png|200px
 |caption1=[[Murnpeowie]] meteorite, an [[iron meteorite]] with [[wikt:regmaglypt|regmaglypts]] (thumprint-like depressions), from ablation caused by aerodynamic heating during fall
 |caption2=[[Marília (meteorite)|Marília Meteorite]], a [[chondrite]] H4, which fell in [[Marília]], Brazil, in 1971
 |caption3=A cut and polished slice of the [[Esquel (meteorite)|Esquel meteorite]], a stony-iron [[pallasite]]. Yellow-green [[olivine]] crystals are encased in the iron-nickel [[Matrix (geology)|matrix]].
 |caption4=Close-packed chondrules in a primitive chondrite NWA 10499. 
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Most meteorites are stony meteorites, classed as [[chondrite]]s and [[achondrite]]s. Only about 6% of meteorites are [[iron meteorite]]s or a blend of rock and metal, the [[Pallasite|stony-iron meteorite]]s. Modern classification of meteorites is complex. The review paper of Krot et al. (2007)<ref name="Krot:2007">{{cite book |volume=1 |title=Treatise on Geochemistry |chapter=1.05 Classification of Meteorites |doi=10.1016/B0-08-043751-6/01062-8 |isbn=978-0-08-043751-4 |first1=A.N. |last1=Krot |first2=K. |last2=Keil |first3=E.R.D. |last3=Scott |first4=C.A. |last4=Goodrich |first5=M.K. |last5=Weisberg |editor-last=Holland| editor-first=Heinrich D. |editor2-first=Karl K.|editor2-last=Turekian |pages=83–128 |publisher=Elsevier Ltd |year=2007}}</ref> summarizes modern meteorite taxonomy.

About 86% of the meteorites are chondrites,<ref name="mbdb-2011">[http://www.lpi.usra.edu/meteor/metbull.php Meteoritical Bulletin Database] {{Webarchive|url=https://web.archive.org/web/20130629182647/http://www.lpi.usra.edu/meteor/metbull.php |date=29 June 2013 }}. Lpi.usra.edu (1 January 2011). Retrieved on 17 December 2011.</ref><ref>[http://internt.nhm.ac.uk/jdsml/research-curation/projects/metcat// The NHM Catalogue of Meteorites] {{Webarchive|url=https://web.archive.org/web/20080330004011/http://internt.nhm.ac.uk/jdsml/research-curation/projects/metcat// |date=30 March 2008 }}. Internt.nhm.ac.uk. Retrieved on 17 December 2011.</ref><ref>[http://www.metbase.de/ MetBase] {{Webarchive|url=https://web.archive.org/web/20160603040235/http://www.metbase.de/ |date=3 June 2016 }}. Metbase.de. Retrieved on 17 December 2011.</ref> which are named for the small, round particles they contain. These particles, or [[chondrule]]s, are composed mostly of silicate minerals that appear to have been melted while they were free-floating objects in space. Certain types of chondrites also contain small amounts of [[Organic material|organic matter]], including [[amino acid]]s, and [[presolar grains]]. Chondrites are typically about 4.55&nbsp;billion years old and are thought to represent material from the [[asteroid belt]] that never coalesced into large bodies. Like [[comet]]s, chondritic asteroids are some of the oldest and most primitive materials in the [[Solar System]]. Chondrites are often considered to be "the building blocks of the planets".

About 8% of the meteorites are [[achondrite]]s (meaning they do not contain chondrules), some of which are similar to terrestrial [[igneous rock]]s. Most achondrites are also ancient rocks, and are thought to represent crustal material of differentiated planetesimals. One large family of achondrites (the [[HED meteorite]]s) may have originated on the parent body of the [[Vesta family|Vesta Family]], although this claim is disputed.<ref>{{cite web |url=http://www.nasa.gov/mission_pages/dawn/ceresvesta/ |title=Dawn's Targets – Vesta and Ceres |publisher=Nasa.gov |date=12 July 2011 |access-date=4 May 2013 |archive-date=13 January 2021 |archive-url=https://web.archive.org/web/20210113072038/https://www.nasa.gov/mission_pages/dawn/ceresvesta/  }}</ref><ref>{{cite journal|title=Vesta and extensively melted asteroids: Why HED meteorites are probably not from Vesta |journal=Earth and Planetary Science Letters |year=2013 |doi=10.1016/j.epsl.2013.09.002 |bibcode=2013E&PSL.381..138W |volume=381 |pages=138–146|last1=Wasson |first1=John T. }}</ref> Others derive from unidentified asteroids. Two small groups of achondrites are special, as they are younger and do not appear to come from the asteroid belt. One of these groups comes from the Moon, and includes rocks similar to those brought back to Earth by [[Apollo program|Apollo]] and [[Luna programme|Luna]] programs. The other group is almost certainly from [[Mars]] and constitutes the only materials from other planets ever recovered by humans.

About 5% of meteorites that have been seen to fall are [[iron meteorite]]s composed of iron-[[nickel]] [[alloy]]s, such as [[kamacite]] and/or [[taenite]]. Most iron meteorites are thought to come from the cores of planetesimals that were once molten. As with the Earth, the denser metal separated from silicate material and sank toward the center of the planetesimal, forming its core. After the planetesimal solidified, it broke up in a collision with another planetesimal. Due to the low abundance of iron meteorites in collection areas such as Antarctica, where most of the meteoric material that has fallen can be recovered, it is possible that the percentage of iron-meteorite falls is lower than 5%. This would be explained by a recovery bias; laypeople are more likely to notice and recover solid masses of metal than most other meteorite types. The abundance of iron meteorites relative to total Antarctic finds is 0.4%.<ref>{{cite web| url = http://www.lpi.usra.edu/meteor/metbull.php?sea=%2A&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=Antarctica&srt=name&categ=Iron+meteorites&mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&dr=&page=1| title = Meteoritical Bulletin: Antarctic Iron Meteorites| access-date = 3 June 2014| archive-date = 29 November 2020| archive-url = https://web.archive.org/web/20201129023051/https://www.lpi.usra.edu/meteor/metbull.php?sea=*&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=Antarctica&srt=name&categ=Iron+meteorites&mblist=All&rect=&phot=&snew=0&pnt=Normal| url-status = live}}</ref><ref>{{cite web| url = http://www.lpi.usra.edu/meteor/metbull.php?sea=%2A&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=Antarctica&srt=name&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&dr=&page=1| title = Meteoritical Bulletin: All Antarctic Meteorites| access-date = 3 June 2014| archive-date = 23 August 2016| archive-url = https://web.archive.org/web/20160823031439/http://www.lpi.usra.edu/meteor/metbull.php?sea=*&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=Antarctica&srt=name&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normal| url-status = live}}</ref>

[[Stony-iron meteorite]]s constitute the remaining 1%. They are a mixture of iron-nickel metal and [[silicate]] minerals. One type, called [[pallasite]]s, is thought to have originated in the boundary zone above the core regions where iron meteorites originated. The other major type of stony-iron meteorites is the [[mesosiderite]]s.

[[Tektites]] (from Greek ''tektos'', molten) are not themselves meteorites, but are rather natural glass objects up to a few centimeters in size that were formed—according to most scientists—by the impacts of large meteorites on Earth's surface. A few researchers have favored tektites originating from the [[Moon]] as volcanic ejecta, but this theory has lost much of its support over the last few decades.