Editing Obsidian

{{Use American English|date=September 2024}}
{{Short description|Naturally occurring volcanic glass}}
{{Other uses}}
{{pp-vandalism|small=yes}}
{{Use mdy dates|date=September 2024}}
{{Infobox mineral
| name          = Obsidian
| category      = [[Volcanic glass]]
| boxwidth      =
| boxbgcolor    = #dddddd
| image         = Lipari-Obsidienne (5).jpg
| imagesize     =
| caption       =
| formula       =
| molweight     = 
| color         = usually black; sometimes green or brown; rarely yellow, orange, red or blue<ref name="Geolcom">{{cite web|url=https://geology.com/rocks/obsidian.shtml|title=Obsidian|publisher=Geology.com|access-date=February 3, 2023|author=King, Hobart M.}}</ref>
| habit         =
| system        =
| twinning      =
| cleavage      =
| fracture      = [[Conchoidal]]
| tenacity      =
| mohs          = 5–6<ref>{{cite book|author=Peter Roger Stuart Moorey|title=Ancient Mesopotamian Materials and Industries: the archaeological evidence|url=https://books.google.com/books?id=P_Ixuott4doC&pg=PA108|year=1999|publisher=Eisenbrauns|isbn=978-1-57506-042-2|pages=108–}}</ref>
| luster        = [[Vitreous lustre|Vitreous]]
| polish        = 
| other      =Texture: Smooth; glassy
| refractive    =
| opticalprop   = [[Translucent]]
| birefringence = 
| dispersion    =
| pleochroism   =
| fluorescence  =
| absorption    =
| streak        =
| gravity       = c. 2.4<ref>{{cite journal|last1=Ericson|first1=J.E.|last2=Makishima|first2=A.|last3=Mackenzie|first3=J.D.|last4=Berger|first4=R.|title=Chemical and physical properties of obsidian: a naturally occurring &#91;sic&#93; glass|journal=Journal of Non-Crystalline Solids|date=January 1975|volume=17|issue=1|pages=129–142|doi=10.1016/0022-3093(75)90120-9|bibcode=1975JNCS...17..129E}}</ref>
| density       =
| melt          = {{convert|700|-|1050|C|F}}{{Citation needed|date=February 2025}}
| fusibility    =
| diagnostic    =
| solubility    =
| diaphaneity   = 
| references =<ref>{{Mindat|id=8519|name=Obsidian}}</ref>
}}

'''Obsidian''' ({{IPAc-en|ə|b|ˈ|s|ɪ|d|i|.|ən|,_|ɒ|b|-}} {{respell|əb|SID|ee|ən|_|ob|-}})<ref>{{cite Dictionary.com|obsidian}}</ref> is a naturally occurring [[volcanic glass]] formed when [[lava]] [[extrusive rock|extruded]] from a [[volcano]] cools rapidly with minimal [[crystal growth]]. It is an [[igneous rock]].<ref>{{cite book|last=Rafferty|first=John P.|title=Rocks|date=2012|publisher=Britannica Educational Pub. in association with Rosen Educational Services|location=New York, NY|isbn=9781615304929|page=97|edition=1st}}</ref> Produced from [[felsic]] lava, obsidian is rich in the lighter elements such as [[silicon]], [[oxygen]], [[aluminium]], [[sodium]], and [[potassium]]. It is commonly found within the margins of [[rhyolite|rhyolitic]] lava flows known as obsidian flows. These flows have a high content of [[silicon dioxide|silica]], giving them a high [[viscosity]]. The high viscosity inhibits the [[atomic diffusion|diffusion of atoms]] through the lava, which inhibits the first step ([[nucleation]]) in the formation of mineral [[crystals]]. Together with rapid cooling, this results in a natural glass forming from the lava.<ref>{{cite book|last1=Raymond|first1=Loren A.|title=Petrology : the study of igneous, sedimentary, metamorphic rocks|date=1995|publisher=Wm. C. Brown|location=Dubuque, Iowa|isbn=0697001903|page=27}}</ref>

Obsidian is hard, [[Brittleness|brittle]], and [[amorphous]]; it therefore [[Fracture (mineralogy)#Conchoidal fracture|fractures]] with sharp edges. In the past, it was used to manufacture cutting and piercing tools, and it has been used experimentally as surgical [[scalpel]] blades.<ref>{{cite book|author1=Brian Cotterell|author2=Johan Kamminga|title=Mechanics of pre-industrial technology: an introduction to the mechanics of ancient and traditional material culture|url=https://books.google.com/books?id=0-xOM8y6Uc8C&pg=PA127|access-date=September 9, 2011|year=1992|publisher=Cambridge University Press|isbn=978-0-521-42871-2|pages=127–}}</ref>

==Origin and properties==
[[File:ObsidianDomeCA.JPG|thumb|Obsidian [[Scree|talus]] at [[Obsidian Dome, California]]]]
[[File:Schneeflockenobsidian-Daumenstein.JPG|thumb|Polished snowflake obsidian, formed through the inclusion of [[cristobalite]] crystals]]

The ''[[Natural History (Pliny)|Natural History]]'' by the Roman writer [[Pliny the Elder]] includes a few sentences about a volcanic glass called obsidian (''lapis obsidianus''), discovered in Ethiopia by Obsidius, a Roman explorer.<ref>''[[Dictionary of Greek and Roman Biography and Mythology]]'', [https://archive.org/stream/dictionaryofgree03smituoft#page/2/mode/2up vol. III, p. 2 ("Obsidius")].</ref><ref>[http://www.encyclopedia.com/doc/1O27-obsidian.html obsidian]. The Concise Oxford Dictionary of English Etymology. Oxford University Press (1996). Retrieved November 20, 2011.</ref><ref>D Harper. [http://www.etymonline.com/index.php?allowed_in_frame=0&search=obsidian&searchmode=none obsidian]. Etymology online. June 17, 2012</ref><ref>M H Manser. [https://books.google.com/books?id=ltGvUYNkr8MC&pg=PA342 The Facts On File Dictionary of Allusions]. Infobase Publishing, 2008, {{ISBN|0816071055}}.</ref>

Obsidian is formed from quickly cooled [[lava]].<ref>M E Malainey. [https://books.google.com/books?id=GUlunYOdWvAC&pg=PA150''A Consumer's Guide to Archaeological Science: Analytical Techniques''], Springer, 2010 {{ISBN|1441957030}}</ref><ref name="Svarney">{{cite book|url=https://archive.org/details/isbn_9781578591565_0|url-access=registration|page=[https://archive.org/details/isbn_9781578591565_0/page/123 123]|author1=P L Barnes-Svarney|author2=T E Svarney|publisher=Visible Ink Press|year=2004|title=The Handy Geology Answer Book|isbn=978-1578591565}}</ref><ref name="Società Italiana di Fisica">{{cite book|url=https://books.google.com/books?id=IURum42ob9UC&pg=PA422|author1=M Martini|author2=M Milazzo|author3=M Piacentini|author4=Società Italiana di Fisica|publisher=IOS Press|year=2004|title=Physics Methods in Archaeometry|volume=154|isbn=978-1586034245}}</ref> Extrusive formation of obsidian may occur when [[felsic]] lava cools rapidly at the edges of a felsic lava flow or volcanic dome, or when lava cools during sudden contact with water or air. Intrusive formation of obsidian may occur when felsic lava cools along the edges of a [[dike (geology)|dike]].<ref>{{cite journal|last1=Putnam|first1=William C.|title=The Mono Craters, California|journal=Geographical Review|year=1938|volume=28|issue=1|pages=68–82|doi=10.2307/210567|jstor=210567|bibcode=1938GeoRv..28...68P|s2cid=163772761|url=https://resolver.caltech.edu/CaltechAUTHORS:20191121-125600648}}</ref><ref>{{cite journal|last1=Binder|first1=Didier|last2=Gratuze|first2=Bernard|last3=Mouralis|first3=Damase|last4=Balkan-Atlı|first4=Nur|title=New investigations of the Göllüdağ obsidian lava flows system: a multi-disciplinary approach|journal=Journal of Archaeological Science|date=December 1, 2011|volume=38|issue=12|pages=3174–3184|doi=10.1016/j.jas.2011.05.014|bibcode=2011JArSc..38.3174B}}</ref>

[[Tektite]]s were once thought by many to be obsidian produced by [[moon|lunar]] volcanic eruptions,<ref>{{cite journal|last1=O'Keefe|first1=John A.|title=The Tektite Problem|journal=Scientific American|volume=239|publisher=Munn & Company|year=1978|issue=2|pages=116–127|doi=10.1038/scientificamerican0878-116|jstor=24960359|bibcode=1978SciAm.239b.116O}}</ref> though few scientists now adhere to this [[hypothesis]].<ref>{{cite book|last1=Sevigny|first1=Melissa L.|title=Under desert skies : how Tucson mapped the way to the Moon and planets|date=2016|publisher=Sentinel Peak|location=Tucson|isbn=9781941451045|page=93}}</ref>

Obsidian is mineral-like, but not a true mineral because, as a glass, it is not [[crystal]]line; in addition, its composition is too variable to be classified as a mineral. It is sometimes classified as a [[mineraloid]].<ref name="HandbookSoil">{{cite book|title=Handbook of Soil Sciences: Properties and Processes|publisher=CRC Press|year=2012|isbn=978-1-4398-0306-6|editor-last=Pan Ming Huang|location=Boca Raton|pages=20–24|editor-last2=Yuncong Li|editor-last3=Malcolm E. Sumner|edition=Second}}</ref> Though obsidian is usually dark in color, similar to [[mafic]] rocks such as [[basalt]], the composition of obsidian is extremely felsic. Obsidian consists mainly of SiO<sub>2</sub> ([[silicon dioxide]]), usually 70% by weight or more; the remainder consists of variable amounts of other oxides, mostly oxides of aluminium, iron, potassium, sodium and calcium.<ref name="Liritzis2014">{{cite encyclopedia|last=Liritzis|first=I.|editor1-last=Rink|editor1-first=W.|editor2-last=Thompson|editor2-first=J.|title=Obsidian Hydration Dating|encyclopedia=Encyclopedia of Scientific Dating Methods|url=https://link.springer.com/referenceworkentry/10.1007/978-94-007-6326-5_39-1|year=2014|pages=1–23|publisher=Springer|location=Dordrecht|isbn=978-94-007-6326-5|doi=10.1007/978-94-007-6326-5_39-1|url-access=subscription}}</ref><ref name="Shackley_2022">{{Cite book|last=Shackley|first=M.S.|title=Obsidian: Geology and Archaeology in the North American Southwest|date=2022|publisher=University of Arizona Press|isbn=9780816550036|pages=12}}</ref> Crystalline rocks with a similar composition include [[granite]] and [[rhyolite]]. Because obsidian is [[Metastability|metastable]] at the Earth's surface (over time the glass [[devitrification|devitrifies]], becoming fine-grained mineral crystals), obsidian older than [[Miocene]] in age is rare. Exceptionally old obsidians include a [[Cretaceous]] welded tuff and a partially devitrified [[Ordovician]] [[perlite]].<ref>{{cite journal|last1=Marshall|first1=Royal R.|title=Devitrification of Natural Glass|journal=GSA Bulletin|date=October 1, 1961|volume=72|issue=10|pages=1493–1520|doi=10.1130/0016-7606(1961)72[1493:DONG]2.0.CO;2|bibcode=1961GSAB...72.1493M}}</ref> This transformation of obsidian is accelerated by the presence of water. Although newly formed obsidian has a low water content, typically less than 1% water by weight,<ref>{{cite web|url=http://www.em.gov.bc.ca/mining/GeolSurv/MetallicMinerals/MineralDepositProfiles/profiles/r12.htm|title=Perlite – Mineral Deposit Profiles|publisher=B.C. Geological Survey|access-date=November 20, 2007|url-status=dead|archive-url=https://web.archive.org/web/20080509024955/http://www.em.gov.bc.ca/mining/GeolSurv/MetallicMinerals/MineralDepositProfiles/profiles/r12.htm|archive-date=May 9, 2008}}</ref> it becomes progressively [[Mineral hydration|hydrated]] when exposed to [[groundwater]], forming [[perlite]].

Pure obsidian is usually dark in appearance, though the color varies depending on the impurities present. Iron and other [[transition element]]s may give the obsidian a dark brown to black color. Most black obsidians contain [[nanoparticle|nanoinclusions]] of [[magnetite]], an [[iron oxide]].<ref name="genesis">{{cite journal|last1=Ma|first1=Chi|last2=Rossman|first2=George|year=2013|title=Nanomineralogy of Gemstones: From Genesis to Discovery|url=https://goldschmidtabstracts.info/2013/1661.pdf|journal=Mineralogical Magazine|volume=77|issue=5|pages=1661|doi=10.1180/minmag.2013.077.5.13|access-date=May 1, 2019|hdl=10174/9676|hdl-access=free}}</ref> Very few samples of obsidian are nearly colorless. In some stones, the [[Inclusion (mineral)|inclusion]] of small, white, radially clustered crystals ([[spherulites]]) of the mineral [[cristobalite]] in the black glass produce a blotchy or snowflake pattern (''snowflake obsidian''). Obsidian may contain patterns of gas bubbles remaining from the lava flow, aligned along layers created as the molten rock was flowing before being cooled. These bubbles can produce interesting effects such as a golden sheen (''sheen obsidian''). An [[iridescence|iridescent]], [[rainbow]]-like sheen (''fire obsidian'') is caused by inclusions of [[magnetite]] [[nanoparticle]]s creating [[thin-film interference]].<ref>{{cite journal|last=Nadin|first=E.|year=2007|title=The secret lives of minerals|journal=Engineering & Science|issue=1|pages=10–20|url=http://www.its.caltech.edu/~chima/publications/Secret_Lives_of_Minerals.pdf}}</ref> Colorful, striped obsidian (''rainbow obsidian'') from Mexico contains oriented [[nanorod]]s of [[hedenbergite]], which cause the rainbow striping effects by [[thin-film interference]].<ref name="genesis"/>

==Occurrence==
[[File:Glass Mountain on Medicine Lake Volcano-750px.jpg|thumb|Glass Mountain, a large obsidian flow at [[Medicine Lake Volcano]] in California]]
Obsidian is found near volcanoes in locations which have undergone rhyolitic eruptions. It can be found in Argentina, [[Armenia]], [[Azerbaijan]], Australia,<ref>{{cite journal|last1=Bonetti|first1=R.|last2=Di Cesare|first2=P.|last3=Guglielmetti|first3=A.|last4=Malerba|first4=F.|last5=Migliorini|first5=E.|last6=Oddone|first6=M.|last7=Bird|first7=J. R.|last8=Torrence|first8=R.|last9=Bultitude|first9=R. J.|title=Fission track dating of obsidian source samples from the Willaumez Peninsula, Papua New Guinea and eastern Australia|journal=Records of the Australian Museum|date=November 25, 1998|volume=50|issue=3|pages=277–84|doi=10.3853/j.0067-1975.50.1998.1286|url=https://australianmuseum.net.au/Uploads/Journals/17861/1286.pdf|archive-date=July 21, 2018|access-date=September 18, 2019|archive-url=https://web.archive.org/web/20180721181917/https://australianmuseum.net.au/uploads/journals/17861/1286.pdf|url-status=dead}}</ref> Canada, Chile, [[Georgia (country)|Georgia]], [[Ecuador]], [[El Salvador]], Greece, [[Guatemala]], [[Hungary]], Iceland, [[List of volcanoes in Indonesia|Indonesia]], Italy, Japan, [[Kenya]], Mexico, New Zealand, [[Papua New Guinea]], Peru, [[Volcanoes of Kamchatka|Russia]], Scotland, the [[Canary Islands]], [[Turkey]] and the United States. Obsidian flows which are so large that they can be [[Hiking|hiked]] on are found within the [[caldera]]s of [[Newberry Volcano]] (Big Obsidian Flow,<ref>Forest Service information page [https://www.fs.usda.gov/recarea/deschutes/recreation/recarea/?recid=38304&actid=64]</ref> 700 acres) and [[Medicine Lake Volcano]] in the [[Cascade Range]] of western North America, and at [[Inyo Craters]] east of the Sierra Nevada in California. [[Yellowstone National Park]] has a mountainside containing obsidian located between [[Mammoth Hot Springs]] and the [[Norris Geyser Basin]], and deposits can be found in many other western U.S. states including [[Arizona]], [[Colorado]], [[New Mexico]], [[Texas]], [[Utah]], and [[Washington (state)|Washington]],<ref>[http://www.obsidianlab.com/image_maps/image_maps.html#wa Washington Obsidian Source Map] {{webarchive|url=https://web.archive.org/web/20150821080359/http://www.obsidianlab.com/image_maps/image_maps.html |date=August 21, 2015 }}. Obsidianlab.com. Retrieved November 20, 2011.</ref> [[Oregon]]<ref>[http://www.sourcecatalog.com/or/s_or.html Oregon Obsidian Sources]. Sourcecatalog.com (November 15, 2011). Retrieved 2011-11-20.</ref> and [[Idaho]].

There are only four major deposit areas in the central Mediterranean: [[Lipari]], [[Pantelleria]], [[Palmarola]] and [[Monte Arci]] ([[Sardinia]]).<ref>Iain Morley and [[Colin Renfrew]]. [https://books.google.com/books?id=TzrNgAsJY1MC&pg=PA19 The Archaeology of Measurement: Comprehending Heaven, Earth and Time in Ancient Societies], Cambridge University Press, 2010 {{ISBN|0521119901}}.</ref>

Ancient sources in the Aegean were [[Milos]] and [[Gyali]].<ref name="E Blake, A B Knapp">
{{cite book|url=https://books.google.com/books?id=F15vfrJq8LUC&pg=PA35|author1=E Blake|author2=A B Knapp|publisher=John Wiley & Sons|year=2005|title=The Archaeology Of Mediterranean Prehistory|isbn=978-0631232681}}</ref>

[[Acıgöl]] town and the [[Göllü Dağ]] volcano were the most important sources in central [[Anatolia]], one of the more important source areas in the [[Near Eastern archaeology|prehistoric Near East]].<ref>Prince Mikasa no Miya Takahito. [https://books.google.com/books?id=EtiKgdv7C3IC&pg=PA141 ''Essays on Anatolian Archaeology''], Otto Harrassowitz Verlag, 1993 {{ISBN|3447033959}}.</ref><ref>L Romano. [https://books.google.com/books?id=Vzs8bFFnVeoC&pg=PA305 6 ICAANE], Otto Harrassowitz Verlag, 2010 Volume 3 of Proceedings of the 6th International Congress of the Archaeology of the Ancient Near East: May 5–10, 2009  {{ISBN|3447062177}}.</ref><ref>P R S Moorey. [https://books.google.com/books?id=P_Ixuott4doC&pg=PA66 Ancient Mesopotamian Materials and Industries: The Archaeological Evidence] Eisenbrauns, 1999 {{ISBN|1575060426}}.</ref>

==Prehistoric and historical use==
{{anchor|prehistoric_use_anchor}}
[[File:Arrowhead.jpg|thumb|upright|Obsidian [[arrowhead]]]]

The first known archaeological evidence of usage was in [[Kariandusi]] (Kenya) and other sites of the [[Acheulian]] age (beginning 1.5 million years BP) dated 700,000 BC, although only very few objects have been found at these sites relative to the Neolithic.<ref>{{cite journal|first1=Sarah|last1=Bunny|url=https://books.google.com/books?id=q7v_rDK0uOgC&pg=PA25|title=Ancient trade routes for obsidian|journal=New Scientist|date=April 18, 1985}}</ref><ref>{{cite book|last1=Schmandt-Besserat|first1=D.|volume=3|title=Early technologies|date=1979|publisher=Undena Publications|location=Malibu, Ca.|isbn=0890030316}}</ref><ref>{{cite book|last1=Merrick|first1=H.V.|last2=Brown|first2=F.H.|last3=Nash|first3=W.P.|title=Society, Culture, and Technology in Africa Import.|date=1994|publisher=Univ Museum Pubns|volume=11|isbn=1931707057|url=https://books.google.com/books?id=12K5JmVC8tYC&pg=PA29}}</ref><ref>J. D. Fage. [https://books.google.com/books?id=jjBYQCpfCNkC&pg=PA30 The Cambridge history of Africa: From c. 1600 to c. 1790, Part 1050], Cambridge University Press, 1979 {{ISBN|0521215927}}</ref><ref>National Museum of Kenya. [http://www.museums.or.ke/content/blogcategory/21/27/ Kariandusi] {{webarchive|url=https://web.archive.org/web/20071024140122/http://www.museums.or.ke/content/blogcategory/21/27/ |date=October 24, 2007 }}. Retrieved June 30, 2012</ref> Manufacture of obsidian bladelets at [[Lipari]] had reached a high level of sophistication by the late Neolithic, and was traded as far as Sicily, the southern Po river valley, and Croatia.<ref>{{cite journal|last1=Martinelli|first1=Maria Clara|last2=Tykot|first2=Robert H.|last3=Vianello|first3=Andrea|title=Lipari (Aeolian islands) obsidian in the late Neolithic. Artifacts, supply, and function|journal=[[Open Archaeology]]|date=April 20, 2019|volume=5|issue=1|pages=46–64|doi=10.1515/opar-2019-0005|doi-access=free|s2cid=150094926}}</ref> Obsidian bladelets were used in ritual [[circumcision]]s and cutting of umbilical cords of newborns.<ref>{{cite journal|last1=Brown|first1=Keri A.|last2=Tykot|first2=Robert H.|title=Obsidian in the Tavoliere, Southeastern Italy — A regional study|journal=Journal of Archaeological Science: Reports|date=August 2018|volume=20|pages=284–292|doi=10.1016/j.jasrep.2018.04.035|bibcode=2018JArSR..20..284B|s2cid=134356403|url=https://www.research.manchester.ac.uk/portal/en/publications/obsidian-in-the-tavoliere-southeastern-italy--a-regional-study(6007b859-88d7-418e-bf69-372627294c35).html}}</ref> Anatolian sources of obsidian are known to have been the material used in the Levant and modern-day Iraqi Kurdistan from a time beginning sometime about 12,500 BC.<ref>{{cite book|url=https://books.google.com/books?id=CT_FWEfanCIC&pg=PA91|title=Archaeological Chemistry|author1=A. M. Pollard|author2=Carl Heron|publisher=Royal Society of Chemistry|year=2008|isbn=978-0854042623}}</ref> Obsidian artifacts are common at [[Tell Brak]], one of the earliest Mesopotamian urban centers, dating to the late fifth millennium BC.<ref>{{cite journal|last1=Oates|first1=J.|last2=McMahon|first2=A.|last3=Karsgaard|first3=P.|last4=Quntar|first4=S. A.|last5=Ur|first5=J.|title=Early Mesopotamian urbanism: a new view from the north|journal=Antiquity|date=January 2, 2015|volume=81|issue=313|pages=585–600|doi=10.1017/S0003598X00095600|s2cid=3803714|url=https://dash.harvard.edu/bitstream/handle/1/4269009/Ur_EarlyMesoUrbanism.pdf?sequence=1}}</ref> Obsidian was valued in [[Stone Age]] cultures because, like [[flint]], it could be fractured to produce sharp blades or arrowheads in a process called [[knapping]]. Like all glass and some other naturally occurring rocks, obsidian breaks with a characteristic [[conchoidal fracture]]. It was also polished to create early [[mirror]]s. Modern [[archaeologists]] have developed a [[relative dating]] system, [[obsidian hydration dating]], to calculate the age of obsidian [[Artifact (archaeology)|artifact]]s.

===Europe===
Obsidian artifacts first appeared in the European continent in Central Europe in the [[Middle Paleolithic]] and had become common by the [[Upper Paleolithic]], although there are exceptions to this. Obsidian played an important role in the [[Neolithic Revolution|transmission of Neolithic knowledge and experiences]]. The material was mainly used for production of [[chipped tools]] which were very sharp due to its nature. Artifacts made of obsidian can be found in many Neolithic cultures across Europe. The source of obsidian for cultures inhabiting the territory of and around Greece was the island of [[Milos]]; the [[Starčevo–Körös–Criș culture]] obtained obsidian from sources in Hungary and Slovakia, while the [[cardium (pottery)|Cardium]]-Impresso cultural complex acquired obsidian from the island outcrops of the central [[Mediterranean]]. Through trade, these artifacts ended up in lands thousands of kilometers away from the original source; this indicates that they were a highly valued commodity.<ref>{{cite journal|last1=Tripković|first1=Boban|title=The Quality and Value In Neolithic Europe: An Alternative View on Obsidian Artifacts|journal=South Eastern Europe Proceedings of the ESF Workshop, Sofia|volume=103|year=2003|pages=119–123|url=https://www.academia.edu/452257|access-date=June 21, 2019}}</ref> [[John Dee]] had a mirror, made of obsidian, which was brought from Mexico to Europe between 1527 and 1530 after Hernando Cortés's conquest of the region.<ref name="bl.uk">{{Cite web|url=https://www.bl.uk/collection-items/john-dees-spirit-mirror|archive-url=https://web.archive.org/web/20200401121456/https://www.bl.uk/collection-items/john-dees-spirit-mirror|url-status=dead|archive-date=April 1, 2020|title=John Dee's spirit mirror – The British Library|date=April 1, 2020|access-date=April 1, 2020}}</ref>

===Middle East and Asia===
[[File:20141231 155025- Prehistoric- Obsidian-Turkey-cropped.jpg|thumb|Obsidian tools from Tilkitepe, Turkey, 5th millennium BC. [[Museum of Anatolian Civilizations]]]]
In the [[Ubaid period|Ubaid]] in the [[5th millennium BC]], blades were manufactured from obsidian extracted from outcrops located in modern-day [[Turkey]].<ref>{{Cite news|url=https://www.nytimes.com/2010/04/06/science/06archeo.html|title=In Syria, a Prologue for Cities|author=John Noble Wilford|date=April 5, 2010|work=The New York Times}}</ref> [[Ancient Egypt]]ians used obsidian imported from the eastern Mediterranean and southern [[Red Sea]] regions. Obsidian [[scalpel]]s older than 2100 BC have been found in a Bronze Age settlement in Turkey.<ref>{{cite web|url=https://www.newscientist.com/article/mg20727750-200-scalpels-and-skulls-point-to-bronze-age-brain-surgery/|title=Scalpels and skulls point to Bronze Age brain surgery|author=Jo Marchant|work=New Scientist}}</ref> In the eastern Mediterranean area the material was used to make tools, mirrors and decorative objects.<ref name="George Robert Rapp">{{cite book|url=https://books.google.com/books?id=7VMVguiMmY0C&pg=PA81|author=George Robert Rapp|publisher=Springer|year=2002|title=Archaeomineralogy|isbn=978-3540425793}}</ref>

The use of obsidian tools was present in Japan near areas of volcanic activity.<ref>{{Cite web|url=http://www.oki-geopark.jp/en/episode/lifestyle/history/obsidian/|title=Obsidian &#124; Oki Islands UNESCO Global Geopark}}</ref><ref>{{cite journal|last1=Izuho|first1=Masami|last2=Sato|first2=Hiroyumi|year=2007|title=Archaeological obsidian studies in Hokkaido, Japan: Retrospect and prospects|journal=Indo-Pacific Prehistory Association Bulletin|volume=27|doi=10.7152/bippa.v27i0.11982|doi-broken-date=November 1, 2024|url=https://journals.lib.washington.edu/index.php/BIPPA/article/download/11982/10607|access-date=March 2, 2022}}</ref> Obsidian was [[Hoshikuso Pass obsidian mine site|mined during the Jōmon period]].

Obsidian has also been found in [[Gilat]], a site in the western [[Negev]] in Israel. Eight obsidian artifacts dating to the [[Chalcolithic]] Age found at this site were traced to obsidian sources in [[Anatolia]]. [[Neutron activation analysis]] (NAA) on the obsidian found at this site helped to reveal trade routes and exchange networks previously unknown.<ref>{{cite journal|last1=Yellin|first1=Joseph|last2=Levy|first2=Thomas E.|last3=Rowan|first3=Yorke M.|title=New Evidence on Prehistoric Trade Routes: The Obsidian Evidence from Gilat, Israel|journal=Journal of Field Archaeology|year=1996|volume=23|issue=3|pages=361–68|doi=10.1179/009346996791973873}}</ref>

===Americas===
{{see also|Obsidian use in Mesoamerica}}
[[File:ObsidianWareLopezMAPHidalgo2.JPG|thumb|left|Obsidian worked into plates and other wares by Victor Lopez Pelcastre of Nopalillo, Epazoyucan, Hidalgo. On display at the [[Museo de Arte Popular, Mexico City]].]]
[[Lithic analysis]] helps to understand pre-Hispanic groups in [[Mesoamerica]]. A careful analysis of obsidian in a culture or place can be of considerable use to reconstruct commerce, production, and distribution, and thereby understand economic, social and political aspects of a civilization. This is the case in [[Yaxchilán]], a Maya city where even warfare implications have been studied linked with obsidian use and its debris.<ref>{{cite journal|last=Brokmann|first=Carlos|title=Tipología y análisis de la obsidiana de Yaxchilán, Chiapas|journal=Colección Científica|number=422|publisher=INAH|year=2000|language=es}}</ref> Another example is the archeological recovery at coastal [[Chumash people|Chumash]] sites in California, indicating considerable trade with the distant site of [[Casa Diablo Hot Springs]] in the [[Sierra Nevada (U.S.)|Sierra Nevada]].<ref>{{cite web|first=CM|last=Hogan|year=2008|url=http://www.megalithic.co.uk/article.php?sid=18502|title=Morro Creek|editor=A. Burnham|website=Megalithic.co.uk|access-date=November 20, 2011}}</ref>

Obsidian tools found in [[Mission Santa Clara]] has shown the existence of exchange networks between various tribes in [[California]]. Obsidian in California comes from 5 major locations all around the state, and when Mission Santa Clara was built, the tribes took their obsidian tools with them and from the analysis the of the obsidian tools it showed that all 5 major location of obsidian were present.<ref>Panich, L. M. (2016). Beyond the colonial curtain: Investigating indigenous use of obsidian in Spanish California through the PXRF analysis of artifacts from Mission Santa Clara. Journal of Archaeological Science: Reports, 5, 521–530. https://doi.org/10.1016/j.jasrep.2016.01.008 </ref>

[[File:Takalik Abaj obsidian 1.jpg|thumb|Raw obsidian and obsidian blades from the Mayan site of Takalik Abaj]]
[[Pre-Columbian]] Mesoamericans' [[Obsidian use in Mesoamerica|use of obsidian]] was extensive and sophisticated; including carved and worked obsidian for tools and decorative objects. Mesoamericans also made a type of sword with obsidian blades mounted in a wooden body. Called a ''[[macuahuitl]]'', the weapon could inflict terrible injuries, combining the sharp cutting edge of an obsidian blade with the ragged cut of a serrated weapon. The [[polearm]] version of this weapon was called ''[[tepoztopilli]]''.

[[Mirrors in Mesoamerican culture|Obsidian mirrors]] were used by some Aztec priests to conjure visions and make prophecies. They were connected with [[Tezcatlipoca]], god of obsidian and sorcery, whose name can be translated from the Nahuatl language as 'Smoking Mirror'.<ref name="bl.uk"/>

[[File:Obsidian from Milos in Crete, 3000-2300 BC, AMH, 144707.jpg|thumb|left|Obsidian imported from [[Milos]], found in [[Minoan civilization|Minoan Crete]]]]
Indigenous people traded obsidian throughout the Americas. Each [[volcano]] and in some cases each volcanic eruption produces a distinguishable type of obsidian allowing archaeologists to use methods such as non-destructive energy dispersive X-ray fluorescence to select minor element compositions from both the artifact and geological sample to trace the origins of a particular artifact.<ref>{{Cite journal|last1=Panich|first1=Lee|last2=Michelini|first2=Antonio|last3=Shackley|first3=M.|date=December 1, 2012|title=Obsidian Sources of Northern Baja California: The Known and the Unknown|url=https://scholarcommons.scu.edu/anthro_fac_pubs/38|journal=Faculty Publications}}</ref> Similar tracing techniques have also allowed obsidian in Greece to be identified as coming from [[Milos]], [[Nisyros]] or [[Gyali]], islands in the [[Aegean Sea]]. Obsidian cores and blades were traded great distances inland from the coast.<ref>{{Cite journal|last1=Stark|first1=Barbara L.|last2=Boxt|first2=Matthew A.|last3=Gasco|first3=Janine|last4=González Lauck|first4=Rebecca B.|last5=Hedgepeth Balkin|first5=Jessica D.|last6=Joyce|first6=Arthur A.|last7=King|first7=Stacie M.|last8=Knight|first8=Charles L. F.|last9=Kruger|first9=Robert|date=March 1, 2016|title=Economic growth in Mesoamerica: Obsidian consumption in the coastal lowlands|journal=Journal of Anthropological Archaeology|volume=41|pages=263–282|doi=10.1016/j.jaa.2016.01.008|issn=0278-4165|doi-access=free}}</ref>

In Chile obsidian tools from [[Chaitén Volcano]] have been found as far away as in [[Chan-Chan]] {{convert|400|km|abbr=on}} north of the volcano, and also in sites 400&nbsp;km south of it.<ref name=pino>{{cite journal|author1=Mario Pino Quivido|author2=Rayen Navarro|name-list-style=amp|title=Geoarqueología del sitio arcaico Chan-Chan 18, costa de Valdivia: Discriminación de ambientes de ocupación humana y su relación con la transgresión marina del Holoceno Medio|journal=Revista Geológica de Chile|year=2005|doi=10.4067/S0716-02082005000100004|volume=32|doi-access=free}}</ref><ref>{{cite journal|last=Naranjo|first=José A|author2=Stern, Charles R|title=Holocene tephrochronology of the southernmost part (42°30'–45°S) of the Andean Southern Volcanic Zone|year=2004|volume=31|issue=2|pages=225–40|oclc=61022562|doi=10.4067/S0716-02082004000200003|journal=Revista Geológica de Chile|doi-access=free}}</ref>

===Oceania===
The [[Lapita culture]], active across a large area of the Pacific Ocean around 1000 BC, made widespread use of obsidian tools and engaged in long distance obsidian trading. The complexity of the production technique for these tools, and the care taken in their storage, may indicate that beyond their practical use they were associated with prestige or high status.<ref name="Specht2018">{{Cite book|last=Specht|first=Jim|editor-last1=Cochrane|editor-first1=Ethan E.|url=https://books.google.com/books?id=JZRODwAAQBAJ|title=The Oxford Handbook of Prehistoric Oceania|chapter=Research issues in the circum-New Guinea islands|editor-last2=Hunt|editor-first2=Terry L.|date=2018|publisher=Oxford University Press|page=100|isbn=978-0-19-992507-0|language=en}}</ref>

Obsidian was also used on [[Easter Island|Rapa Nui]] (Easter Island) for edged tools such as ''Mataia'' and the pupils of the eyes of their [[Moai]] (statues), which were encircled by rings of bird bone.<ref>Eric Kjellgren; JoAnne Van Tilburg; Adrienne Lois Kaeppler (2001). Splendid Isolation: Art of Easter Island. Metropolitan Museum of Art. pp. 39–. {{ISBN|978-1-58839-011-0}}.</ref> Obsidian was used to inscribe the [[Rongorongo|Rongorongo glyphs]].

==Current use==
Obsidian can be used to make extremely sharp knives, and obsidian blades are a type of [[glass knife]] made using naturally occurring obsidian instead of manufactured glass. Obsidian is used by some surgeons for [[scalpel]] blades, although this is not approved by the [[US Food and Drug Administration]] (FDA) for use on humans.<ref>{{Cite web|last=Shadbolt|first=Peter|date=April 2, 2015|title=CNN Health: How Stone Age blades are still cutting it in modern surgery|url=https://www.cnn.com/2015/04/02/health/surgery-scalpels-obsidian/index.html|access-date=September 7, 2023|publisher=CNN|language=en}}</ref> Well-crafted obsidian blades, like any glass knife, can have a cutting edge many times sharper than high-quality steel surgical scalpels: the cutting edge of the blade is only about three nanometers thick.<ref name=obsidian1>{{cite journal|last=Buck|first=BA|date=March 1982|title=Ancient Technology in Contemporary Surgery|journal=The Western Journal of Medicine|volume=136|issue=3|pages=265–269|pmid=7046256|pmc=1273673}}</ref> All metal knives have a jagged, irregular blade when viewed under a strong enough [[microscope]]; however, obsidian blades are still smooth, even when examined under an [[scanning electron microscope|electron microscope]].<ref name="Haviland">{{cite book|last=Haviland|first=W.A.|author2=Prins H.E.L.|author3=Walrath D.|author4=McBride B.|title=Anthropology: The Human Challenge|publisher=Cengage Learning|year=2010|edition=13|pages=196|isbn=9780495810841|url=https://books.google.com/books?id=Fm2RY5ZKmDIC&q=%22payson+sheets%22+obsidian+blade&pg=PA196|access-date=September 27, 2012}}</ref> One study found that obsidian incisions produced fewer [[inflammatory cell]]s and less [[granulation tissue]] in a group of rats after seven days but the differences disappeared after twenty-one days.<ref>{{cite journal|last1=Disa|first1=J. J.|last2=Vossoughi|first2=J.|last3=Goldberg|first3=N. H.|title=A comparison of obsidian and surgical steel scalpel wound healing in rats.|journal=Plastic and Reconstructive Surgery|date=October 1993|volume=92|issue=5|pages=884–887|doi=10.1097/00006534-199392050-00015|pmid=8415970}}</ref> [[Don Crabtree]] has produced surgical obsidian blades and written articles on the subject.<ref name="obsidian1" /> Obsidian scalpels may be purchased for surgical use on [[Animal testing|research animals]].<ref name="FST Obsidian Scalpels">{{cite web|last=Fine Science Tools (FST)|title=FST product catalog|url=http://www.finescience.com/Special-Pages/Products.aspx?ProductId=296&CategoryId=56|publisher=FST|access-date=September 7, 2012}}</ref>

The major disadvantage of obsidian blades is their brittleness compared to those made of metal,<ref>Fine Science Tools – "[https://www.finescience.com/en-US/Products/Scalpels-Blades/Micro-Knives/Obsidian-Scalpels Obsidian Scalpels]" </ref> thus limiting the surgical applications for obsidian blades to a variety of specialized uses where this is not a concern.<ref name = "obsidian1" />

[[File:Pig.snowobsidian.jpg|thumb|right|Pig carved in snowflake obsidian, 10 centimeters (4 in) long. The markings are [[spherulite]]s.]]
Obsidian is also used for ornamental purposes and as a [[gemstone]].<ref>{{Cite book|url=https://books.google.com/books?id=2UX1CAAAQBAJ&q=%C2%A0Obsidian+is+also+used+for+ornamental+purposes+and+as+a+gemstone.&pg=PA502|title=Dictionary of Gems and Gemology|last=Manutchehr-Danai|first=Mohsen|date=March 9, 2013|publisher=Springer Science & Business Media|isbn=9783662042885|language=en}}</ref> It presents a different appearance depending on how it is cut: in one direction it is jet black, while in another it is glistening gray. "[[Apache tears]]" are small rounded obsidian nuggets often embedded within a grayish-white perlite [[Matrix (geology)|matrix]].

[[Pedestal|Plinths]] for [[phonograph|audio turntables]] have been made of obsidian since the 1970s, such as the grayish-black SH-10B3 plinth by [[Technics (brand)|Technics]].

==See also==
<!-- PLEASE RESPECT ALPHABETICAL ORDER -->
* {{annotated link|Apache tears}}
* {{annotated link|Helenite}}
* {{annotated link|Hyaloclastite}} and [[tachylite]] – volcanic glasses with [[basaltic]] composition
* {{annotated link|Knapping}}
* {{annotated link|Libyan desert glass}}
* {{annotated link|Mayor Island / Tūhua}} – a source of Māori obsidian tools
* {{annotated link|Obsidian hydration dating}}
* {{annotated link|Stone tool}}
* {{annotated link|Vitrophyre}}
* {{annotated link|Yaxchilan Lintel 24}} – Ancient carving showing a Maya bloodlet ritual involving a rope with obsidian shards.

==References==
{{reflist}}

==External links==
{{commons and category}}
* [https://volcanoes.usgs.gov/vsc/glossary/obsidian.html USGS definition of obsidian]

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{{Volcanoes}}
{{Rock type}}
{{Authority control}}

[[Category:Obsidian|*]]
[[Category:Gemstones]]
[[Category:Vitreous rocks]]
[[Category:Volcanology]]