Chemistry:Meteoric iron

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Short description: Iron originating from a meteorite rather than from the Earth since formation
Meteoric iron (native iron)
TolucaMeteorite.jpg
Widmanstätten pattern on a 500g endcut from the Toluca iron meteorite
General
CategoryNative element mineral
Formula
(repeating unit)
Fe and Ni in different ratios
Space groupDifferent structures
Identification
|re|er}}Metallic
DiaphaneityOpaque

Meteoric iron, sometimes meteoritic iron,[1] is a native metal and early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenite. Meteoric iron makes up the bulk of iron meteorites but is also found in other meteorites. Apart from minor amounts of telluric iron, meteoric iron is the only naturally occurring native metal of the element iron (in metallic form rather than in an ore) on the Earth's surface.[2]

Mineralogy

The bulk of meteoric iron consists of taenite and kamacite. Taenite is a face-centered cubic and kamacite a body-centered cubic iron-nickel alloy.

Meteoric iron can be distinguished from telluric iron by its microstructure and perhaps by its chemical composition also, since meteoritic iron contains more nickel and less carbon.[2]

Trace amounts of gallium and germanium in meteoric iron can be used to distinguish different meteorite types. The meteoric iron in stony iron meteorites is identical to the "gallium-germanium group" of the iron meteorites.[3]

Overview over meteoric iron mineral phases
Mineral Formula Nickel (Mass-% Ni) Crystal structure Notes & references
Antitaenite γLow Spin-(Ni,Fe) 20–40 face centered cubic Only approved as a variety of taenite by the IMA
Kamacite α-(Fe,Ni); Fe0+0.9Ni0.1 5–10 body centered cubic Same structure as ferrite
Taenite γ-(Ni,Fe) 20–65 face centered cubic Same structure as austenite
Tetrataenite (FeNi) 48–57 tetragonal [4]

Structures

Meteoric iron forms a few different structures that can be seen by etching or in thin sections of meteorites. The Widmanstätten pattern forms when meteoric iron cools and kamacite is exsolved from taenite in the form of lamellas.[5] Plessite is a more fine-grained intergrowth of the two minerals in between the lamella of the Widmanstätten pattern.[6] Neumann lines are fine lines running through kamacite crystals that form through impact-related deformation.[7]

Cultural and historical usage

A lance made from a narwhal tusk with an iron head made from the Cape York meteorite.

Before the advent of iron smelting, meteoric iron was the only source of iron metal apart from minor amounts of telluric iron. Meteoric iron was already used before the beginning of the Iron Age to make cultural objects, tools and weapons.[8]

Bronze Age

Iron in hieroglyphs
<hiero>b-i-A-F18:n:pt-</hiero>
bjꜣ-n-p.t
literally "metal of the sky"

Many examples of iron working from the Bronze Age have been confirmed to be meteoritic in origin.[9]

  • In ancient Egypt an iron metal bead was found in a graveyard near Gerzeh that contained 7.5% Ni.[10][11] Dated to around 3200 BC, geochemical analysis of the Gerzeh iron beads, based on the ratio of nickel to iron and cobalt, confirms that the iron was meteoritic in origin.[9]
  • Dated to around 2500 BC, an iron dagger from Alaca Höyük was confirmed to be meteoritic in origin through geochemical analysis.[9]
  • Dated to around 2300 BC, an iron pendant from Umm el-Marra in Syria was confirmed to be meteoritic in origin through geochemical analysis.[9]
  • Dated to around 1400 BC, an iron axe from Ugarit in Syria was found to be meteoritic in origin.[9]
  • Dated to around 1400 BC, several iron axes from the Shang Dynasty in China were also confirmed to be meteoritic in origin.[9]
  • Dated to around 1350 BC, an iron dagger, bracelet and headrest from the tomb of Tutankhamun were confirmed to be meteoritic in origin.[9] The Tutankhamun dagger consists of similar proportions of metals (iron, nickel and cobalt) to a meteorite discovered in the area, deposited by an ancient meteor shower.[12][13][14]
  • Dated to around 900 BC, an iron arrowhead from Mörigen in Switzerland was confirmed to be meteoritic in origin.[15]

The Americas

  • The Inuit used parts of the Cape York meteorite to make lance heads.[16][17][18]

Africa

  • Fragments from the Gibeon meteorite were used for centuries by the Nama people of Namibia.

Asia

  • There are reports of the use of meteorites for manufacture of various items in Tibet (see Thokcha).
  • The Iron Man, a purported Tibetan Buddhist statue of Vaiśravaṇa, was likely carved from an ataxite meteorite.[19] It has been speculated that it may be made from a fragment of the Chinga meteorite.[20][21]

Even after the invention of smelting, meteoric iron was sometimes used where this technology was not available or metal was scarce. A piece of the Cranbourne meteorite was made into a horseshoe around 1854.[22]

Today meteoritic iron is used in niche jewellery and knife production, but most of it is used for research, educational or collecting purposes.

Atmospheric phenomena

Meteoric iron also has an effect on the Earth's atmosphere. When meteorites descend through the atmosphere, outer parts are ablated. Meteoric ablation is the source of many elements in the upper atmosphere. When meteoric iron is ablated, it forms a free iron atom that can react with ozone (O3) to form FeO. This FeO may be the source of the orange spectrographic bands in the spectrum of the upper atmosphere.[23]

See also

References

  1. Rehren, Thilo; Belgya, Tamás; Jambon, Albert; Káli, György; Kasztovszky, Zsolt; Kis, Zoltán; Kovács, Imre; Maróti, Boglárka et al. (2013). "5,000 years old Egyptian iron beads made from hammered meteoritic iron". Journal of Archaeological Science 40 (12): 4785–4792. doi:10.1016/j.jas.2013.06.002. http://discovery.ucl.ac.uk/1430496/1/Rehren_et_al_2013_Petrie_iron_beads_JAS_40.pdf. 
  2. 2.0 2.1 Fleming, Stuart J.; Schenck, Helen R. (1989). History of Technology: The Role of Metals. UPenn Museum of Archaeology. p. 67. ISBN 978-0-924171-95-6. https://books.google.com/books?id=NKCpAVR011MC&pg=PA67. 
  3. Lovering, John F.; Nichiporuk, Walter; Chodos, Arthur; Brown, Harrison (31 December 1956). "The distribution of gallium, germanium, cobalt, chromium, and copper in iron and stony-iron meteorites in relation to nickel content and structure". Geochimica et Cosmochimica Acta 11 (4): 263–278. doi:10.1016/0016-7037(57)90099-6. Bibcode1957GeCoA..11..263L. 
  4. Clarke, Roy S.; Edward R. D. Scott (1980). "Tetrataenite - ordered FeNi, a new mineral in meteorites". American Mineralogist 65: 624–630. Bibcode1980AmMin..65..624C. http://www.minsocam.org/ammin/AM65/AM65_624.pdf. 
  5. Yang, J.; J. I. Goldstein (2005). "The formation of the Widmanstätten structure in meteorites". Meteoritics & Planetary Science 40 (2): 239–253. doi:10.1111/j.1945-5100.2005.tb00378.x. Bibcode2005M&PS...40..239Y. 
  6. Goldstein, J. I.; J. R. Michael (2006). "The formation of plessite in meteoritic metal". Meteoritics & Planetary Science 41 (4): 553–570. doi:10.1111/j.1945-5100.2006.tb00482.x. Bibcode2006M&PS...41..553G. 
  7. Rosenhain, Walter; Jean McMinn (1925). "The Plastic Deformation of Iron and the Formation of Neumann Lines". Proceedings of the Royal Society 108 (746): 231–239. doi:10.1098/rspa.1925.0071. Bibcode1925RSPSA.108..231R. 
  8. Waldbaum, J. C. and James D. Muhly; The first archaeological appearance of iron and the transition to the iron age chapter in The coming of the age of iron, Theodore A. Wertme. ed., Yale University Press, 1980, ISBN:978-0300024258
  9. 9.0 9.1 9.2 9.3 9.4 9.5 9.6 Jambon, Albert (2017). "Bronze Age iron: Meteoritic or not? A chemical strategy.". Journal of Archaeological Science 88: 47–53. doi:10.1016/j.jas.2017.09.008. ISSN 0305-4403. https://hal.sorbonne-universite.fr/hal-01614724/file/Jambon_Bronze_Age_iron.pdf. 
  10. "Pre-Dynastic Iron Beads from Gerzeh, Egypt". ucl.ac.uk. http://www.ucl.ac.uk/iams/newsletter/accordion/journals/iams_19/iams_19_1995_el_gayer. 
  11. Rehren, Thilo; Belgya, Tamás; Jambon, Albert; Káli, György et al. (31 July 2013). "5,000 years old Egyptian iron beads made from hammered meteoritic iron". Journal of Archaeological Science 40 (12): 4785–4792. doi:10.1016/j.jas.2013.06.002. 
  12. Bjorkman, Judith Kingston (1973). "Meteors and Meteorites in the ancient Near East". Meteoritics 8 (2): 91–132. doi:10.1111/j.1945-5100.1973.tb00146.x. Bibcode1973Metic...8...91B. 
  13. Daniela Comelli; Massimo D'orazio; Luigi Folco; Mahmud El-Halwagy; Tommaso Frizzi; Roberto Alberti; Valentina Capogrosso; Abdelrazek Elnaggar et al. (2016). "The meteoritic origin of Tutankhamun's iron dagger blade". Meteoritics & Planetary Science 51 (7): 1301–1309. doi:10.1111/maps.12664. Bibcode2016M&PS...51.1301C. 
  14. Walsh, Declan (2 June 2016). "King Tut's Dagger Made of 'Iron From the Sky,' Researchers Say". The New York Times. https://www.nytimes.com/2016/06/03/world/middleeast/king-tuts-dagger-made-of-iron-from-the-sky-researchers-say.html. "...the blade's composition of iron, nickel and cobalt was an approximate match for a meteorite that landed in northern Egypt. The result "strongly suggests an extraterrestrial origin"" 
  15. Guy, Jack (8 August 2023). "Arrowhead made from meteorite 3,000 years ago found near lake in Europe". CNN. https://edition.cnn.com/style/article/arrowhead-meteoritic-iron-scli-intl-scn/index.html. 
  16. Iron and steel in ancient times by Vagn Fabritius Buchwald - Det Kongelige Danske Videnskabernes Selskab 2005
  17. T. A. Rickard (1941). "The Use of Meteoric Iron". Journal of the Royal Anthropological Institute 71 (1/2): 55–66. doi:10.2307/2844401. 
  18. Buchwald, V. F. (1992). "On the Use of Iron by the Eskimos in Greenland". Materials Characterization 29 (2): 139–176. doi:10.1016/1044-5803(92)90112-U. 
  19. Der Lama mit der Hose: „Buddha from space“ ist offenbar eine Fälschung (Telepolis 13.10.2012)
  20. "Ancient Buddhist Statue Made of Meteorite, New Study Reveals". Science Daily. https://www.sciencedaily.com/releases/2012/09/120926104255.htm. 
  21. Buchner, Elmar; Schmieder, Martin; Kurat, Gero; Brandstätter, Franz et al. (1 September 2012). "Buddha from space-An ancient object of art made of a Chinga iron meteorite fragment*". Meteoritics & Planetary Science 47 (9): 1491–1501. doi:10.1111/j.1945-5100.2012.01409.x. Bibcode2012M&PS...47.1491B. 
  22. "The Cranbourne Meteorites". City of Casey. http://www.casey.vic.gov.au/include/downloadAttachment.asp?file=/doclib/document3059.pdf&saveAs=History_of_the_Cranbourne_Meteorites_v15Jan12.pdf. 
  23. Evans, W. F. J.; Gattinger, R. L.; Slanger, T. G.; Saran, D. V. et al. (20 November 2010). "Discovery of the FeO orange bands in the terrestrial night airglow spectrum obtained with OSIRIS on the Odin spacecraft". Geophysical Research Letters 37 (22): L22105. doi:10.1029/2010GL045310. Bibcode2010GeoRL..3722105E. 

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