Editing Lonsdaleite (section)

==Occurrence==
[[File:Popigai nanodiamonds.jpg|thumb|Diamond samples from the [[Popigai impact structure]]: (a) is pure diamond, while (b) is diamond with some lonsdaleite impurities.]]
Lonsdaleite occurs as microscopic crystals associated with diamond in several meteorites: [[Canyon Diablo meteorite|Canyon Diablo]],<ref name="Lea 2022">{{cite web |last=Lea |first=Robert |title=Dwarf planet collision may have sent strange ultra-hard diamonds to Earth |website=Space.com |date=2022-09-12 |url=https://www.space.com/meteorite-strange-form-of-diamond |access-date=2022-09-13}}</ref> [[Kenna meteorite|Kenna]], and [[Allan Hills 77283]]. It is also naturally occurring in non-bolide diamond [[placer deposit]]s in the [[Sakha Republic]].<ref>
{{cite journal
  |author=Kaminskii, F.V. |author2=G.K. Blinova |author3=E.M. Galimov |author4=G.A. Gurkina |author5=Y.A. Klyuev |author6=L.A. Kodina |author7=V.I. Koptil |author8=V.F. Krivonos |author9=L.N. Frolova |author10=A.Y. Khrenov
 |date=1985
 |title=Polycrystalline aggregates of diamond with lonsdaleite from Yakutian [Sakhan] placers
 |journal=Mineral. Zhurnal
 |volume=7 |pages=27–36
}}
</ref> Material with d-spacings consistent with Lonsdaleite has been found in sediments with highly uncertain dates at [[Lake Cuitzeo]], in the state of [[Guanajuato]], Mexico, by proponents of the controversial [[Younger Dryas impact hypothesis]],<ref> 
{{cite journal
 |last1=Israde-Alcantara |first1=I.
 |last2=Bischoff |first2=J.L.
 |last3=Dominguez-Vazquez |first3=G.
 |last4=Li       |first4=H.-C.      |last5=Decarli   |first5=P.S.
 |last6=Bunch    |first6=T.E.       |last7=Wittke    |first7=J.H.
 |last8=Weaver   |first8=J.C.       |last9=Firestone |first9=R.B.
 |last10=West    |first10=A.        |last11=Kennett  |first11=J.P.
 |last12=Mercer  |first12=C.        |last13=Xie      |first13=S.
 |last14=Richman |first14=E.K.      |last15=Kinzie   |first15=C.R.
 |last16=Wolbach |first16=W.S.      |display-authors=6
 |year=2012
 |title=Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis
 |journal=Proceedings of the National Academy of Sciences
 |volume=109  |issue=13  |pages=E:738–747
 |pmid=22392980  |doi=10.1073/pnas.1110614109
 |bibcode=2012PNAS..109E.738I  |pmc=3324006
 |doi-access=free
 }}
</ref> which is now refuted by earth scientists and planetary impact specialists.<ref>{{Cite journal |last=Holliday |first=Vance T. |last2=Daulton |first2=Tyrone L. |last3=Bartlein |first3=Patrick J. |last4=Boslough |first4=Mark B. |last5=Breslawski |first5=Ryan P. |last6=Fisher |first6=Abigail E. |last7=Jorgeson |first7=Ian A. |last8=Scott |first8=Andrew C. |last9=Koeberl |first9=Christian |last10=Marlon |first10=Jennifer |last11=Severinghaus |first11=Jeffrey |last12=Petaev |first12=Michail I. |last13=Claeys |first13=Philippe |date=2023-07-26 |title=Comprehensive refutation of the Younger Dryas Impact Hypothesis (YDIH) |url=https://linkinghub.elsevier.com/retrieve/pii/S0012825223001915 |journal=Earth-Science Reviews |language=en |pages=104502 |doi=10.1016/j.earscirev.2023.104502|doi-access=free }}</ref> Claims of Lonsdaleite and other nanodiamonds in a layer of the Greenland ice sheet that could be of Younger Dryas age have not been confirmed and are now disputed.<ref name="Kurbatov Mayewski Steffensen West 2022">{{cite web |last1=Kurbatov |first1=Andrei V. |last2=Mayewski |first2=Paul A. |last3=Steffensen |first3=Jorgen P. |last4=West |first4=Allen |last5=Kennett |first5=Douglas J. |last6=Kennett |first6=James P. |last7=Bunch |first7=Ted E. |last8=Handley |first8=Mike |last9=Introne |first9=Douglas S. |last10=Hee |first10=Shane S. Que |last11=Mercer |first11=Christopher |last12=Sellers |first12=Marilee |last13=Shen |first13=Feng |last14=Sneed |first14=Sharon B. |last15=Weaver |first15=James C. |last16=Wittke |first16=James H. |last17=Stafford |first17=Thomas W. |last18=Donovan |first18=John J. |last19=Xie |first19=Sujing |last20=Razink |first20=Joshua J. |last21=Stich |first21=Adrienne |last22=Kinzie |first22=Charles R. |last23=Wolbach |first23=Wendy S. |title=Discovery of a nanodiamond-rich layer in the Greenland ice sheet |website=PubPeer |date=2022-09-20 |url=https://pubpeer.com/publications/28B83ADB820618B3F374667D5FBB92 |access-date=2022-09-28}}</ref> Its presence in local peat deposits is claimed as evidence for the [[Tunguska event]] being caused by a meteor rather than by a cometary fragment.<ref>
{{cite journal
 |last1=Kvasnytsya |first1=Victor
 |last2=Wirth      |last3=Dobrzhinetskaya |last4=Matzel
 |last5=Jacobsend  |last6=Hutcheon        |last7=Tappero
 |last8=Kovalyukh
 |date=August 2013
 |title=New evidence of meteoritic origin of the Tunguska cosmic body
 |journal=Planetary and Space Science
 |volume=84 |pages=131–140
 |doi=10.1016/j.pss.2013.05.003 |bibcode=2013P&SS...84..131K
 |url=http://gfzpublic.gfz-potsdam.de/pubman/item/escidoc:247242
}}
</ref><ref>
{{cite news
 |last=Redfern |first=Simon
 |title=Russian meteor shockwave circled globe twice
 |work=BBC News
 |date=28 June 2013
 |publisher=[[British Broadcasting Corporation]]
 |url=https://www.bbc.co.uk/news/science-environment-23066055
 |access-date=28 June 2013
}}
</ref>