Editing Impactite

{{Short description|Rock created or modified by impact of a meteorite}}
[[File:Impactites from Monturaqui Impact Crater.jpg|thumb|An example of impactite on Earth (from [[Monturaqui]] impact crater, Chile)]]
'''Impactite''' is [[rock (geology)|rock]] created or modified by one or more impacts of a [[meteorite]].<ref>{{Cite journal|last1=Stöffler|first1=D.|last2=Grieve|first2=R.A.F.|title=Classification and Nomenclature of Impact Metamorphic Rocks: A Proposal to the IUGS Subcommission on the Systematics of Metamorphic Rocks |journal=Lunar and Planetary Science Conference| page = 1347|bibcode = 1994LPI....25.1347S|date=1994}}</ref><ref name=":0">{{Citation|last1=Schmid|first1=Rolf|title=Classification and nomenclature scheme|work=Metamorphic Rocks|pages=3–110|publisher=Cambridge University Press|isbn=978-0-511-62891-7|last2=Fettes|first2=Douglas|last3=Harte|first3=Ben|last4=Davis|first4=Eleutheria|last5=Desmons|first5=Jacqueline|last6=Smulikowski|first6=Witold|last7=Sassi|first7=Francesco|last8=Brodie|first8=Kate|last9=Árkai|first9=Péter|editor2-first=Jacqueline|editor2-last=Desmons|editor1-first=Douglas|editor1-last=Fettes|year=2007|doi=10.1017/cbo9780511628917.003}}</ref> Impactites are considered [[metamorphic rock]], because their [[Protolith|source material]]s were modified by the heat and pressure of the impact.<ref name=":1">{{Cite web|title=Impactites: Impact Breccia, Tektites, Moldavites, Shattercones|url=https://geology.com/meteorites/impactites.shtml|access-date=2020-06-10|website=geology.com}}</ref> On Earth, impactites consist primarily of modified terrestrial material, sometimes with pieces of the original meteorite.<ref name=":1" />

== Formation ==
When a large meteorite hits a planet, it can radically deform the rocks and [[regolith]] that it hits. The heat, pressure, and shock of the impact changes these materials into impactite.<ref name=":1" /> Only very massive impacts generate the heat and pressure needed to transform a rock, so impactites are created rarely.<ref name=":1" />

==Characteristics==
Impactite includes [[Shock metamorphism|shock-metamorphosed]] target rocks, melts ([[suevite]]s) and mixtures of the two, as well as sedimentary rocks with significant impact-derived components (shocked mineral grains, [[tektites]], anomalous geochemical signatures, etc.). In June 2015, NASA reported that '''impact glass''' has been detected on the planet [[Mars]]. Such material may contain preserved signs of [[Life on Mars|ancient life]]—if life existed.<ref name="NASA-20150608">{{cite web |author=Staff |title=PIA19673: Spectral Signals Indicating Impact Glass on Mars |url=http://photojournal.jpl.nasa.gov/catalog/PIA19673 |date=8 June 2015 |work=[[NASA]] |access-date=8 June 2015 }}</ref> Impactites are generally classified into three groups: shocked rocks, impact melt, and impact breccias.<ref name=":0" />

=== Shocked rock ===
Shocked rocks have been transformed by [[shock metamorphism]] caused by the impact. They include [[shatter cone]]s and high-pressure minerals, for example [[coesite]] and [[stishovite]].
[[File:Impactite (Pleistocene, ~816 ka; near Darwin Crater, Tasmania) 14.jpg|thumb|An example of impact glass from the Pleistocene, near Darwin Crater, Tasmania]]

=== Impact melts ===
When a meteor strikes a planet's surface, the energy released from the impact can melt rock and regolith into a liquid. When the liquid cools it forms a solid known as an impact melt.<ref name=":0" /> If the liquid solidifies quickly before the atoms arrange into a [[crystal lattice]], it forms an impact [[glass]]. Impact glass can be dark brown, almost black, and partly transparent.<ref>{{Cite web|last=Temming|first=Maria|title=Exotic Glass Could Help Unravel Mysteries of Mars|website=[[Scientific American]]|url=http://www.scientificamerican.com/article/exotic-glass-could-help-unravel-mysteries-of-mars/|access-date=2015-06-15}}</ref> Sometimes, the cooled liquid does form a crystal structure. In that case, it would still be considered an impact melt, but not an impact glass.<ref name=":0" />

==== Tektites ====
{{Main|Tektite}}
Tektites are a rare kind of impact glass.<ref>{{Citation |last=Koeberl |first=Christian |title=Tektites |date=2024-05-22 |work=Oxford Research Encyclopedia of Planetary Science |url=https://oxfordre.com/planetaryscience/display/10.1093/acrefore/9780190647926.001.0001/acrefore-9780190647926-e-263 |access-date=2025-05-11 |language=en |doi=10.1093/acrefore/9780190647926.013.263 |isbn=978-0-19-064792-6|url-access=subscription }}</ref>

=== Impact breccias ===
[[File:Impact breccia (Late Cretaceous, 70.3 Ma; Kara Impact Structure, Polar Urals, Russia).jpg|thumb|Impact breccia from the Kara impact structure in Russia]]
[[Breccia]] is "a rock consisting of angular fragments cemented together".<ref>{{Cite book |last=Holland |first=Stuart S. |url=http://cmscontent.nrs.gov.bc.ca/geoscience/PublicationCatalogue/Bulletin/BCGS_B048.pdf |title=Landforms of British Columbia: A Physiographic Outline |year=1976 |location=British Columbia, Canada |pages=127 |language=English}}</ref> An impact breccia is formed when a meteor shatters a rock and then cements it back together. Some breccias contain impact melts.<ref name=":1" />

==Examples of impactite==
[[File:PIA19673-Mars-AlgaCrater-ImpactGlassDetected-MRO-20150608.jpg|thumb|[[List of craters on Mars: A-G|Alga crater]] on [[Mars]] is a possible site for preserved [[Life on Mars|ancient life]], after detection of an impact glass deposit.<ref name="NASA-20150608" />]]
Impactite has been found, for example, at the following impact craters and structures:
* [[Alamo bolide impact]] (Late Devonian), Nevada, United States
* [[List of craters on Mars: A-G|Alga crater]] on the planet [[Mars]]<ref name="NASA-20150608" />
* [[Barringer crater]], Arizona, United States<ref>[https://www.meteorite-times.com/jims-fragments/meteor-crater-bomblets/ Meteor Crater Bomblets]</ref>
* [[Charlevoix impact structure]], Québec, Canada
* [[Darwin Crater]], Tasmania (source of [[Darwin glass]])
* [[Lake Lappajärvi]], Finland (source of [[Kärnäite]])
* [[Manicouagan Reservoir|Manicouagan impact structure]], Québec, Canada
* [[Neugrund crater]], Estonia
* [[Nördlinger Ries]] crater, Germany 
* [[Rochechouart impact structure]], France
* [[Stac Fada Member]], Scotland
* [[Wabar craters]], Saudi Arabia

==See also==
* [[Glossary of meteoritics]]
* [[Meteorite shock stage]]
* [[Vitrified sand]]

==References==
{{Reflist}}

==External links==
{{Commons category}}
* [https://web.archive.org/web/20070808072836/http://www.lpi.usra.edu/publications/slidesets/craters/glossary.shtml Meteorite crater glossary]

{{Impact cratering on Earth}}
{{Meteorites}}{{Glass production techniques}}
{{Authority control}}

[[Category:Metamorphic rocks]]
[[Category:Sedimentary rocks]]
[[Category:Meteorite mineralogy and petrology]]
[[Category:Impact event minerals]]
[[Category:Glass in nature]]