Gibeon, Iron, Meteorites, IVA irons, photos, images, Namibia

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Gibeon Iron Meteorites
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Gibeon Iron Meteorites. Their Discovery, History and Research. By Svend Buhl

The Gibeon meteorite strewnfield today
The total known weight of the recovered meteorites today exceeds 26 tons and the preatmospheric size of the Gibeon body was determined larger than 3 meters (Bajo et al. 2008). More than 74 larger masses (>100 kg) are known today and the number of smaller masses (< 30 kg) collected very probably exceeds 1000. The Gibeon meteorite shower is the 6th largest in total mass known at present.

The Gibeon area witnessed fierce fighting, not only 1904/1905 during the Herero war, but also in World War One when the South African Army attacked an outnumbered detachment of the German Colonial Forces near Keetmanshoop and Grotfontein in April and May 1915. Gibeon Station cemetery. Image courtesy of Dr.-Ing. Klaus Dierks

The dimensions of the distribution field are approx. 230 x 115 miles which makes it the largest known meteorite strewn field. In contradiction to other known strewn fields the Gibeon distribution field lacks the typical mass distribution.

Apparently large and smaller masses are spread randomly in the strewn field, with most of the smallest masses concentrated in the central area southeast of Gibeon, where most of the specimens have been found. Obviously the flight parameters of the meteorites were influenced by the kinetics of a significant terminal mid air explosion rather than by the usual aerodynamic forces alone. This way the Gibeon meteorite created rather a distribution fan than an ellipse.

Meteorite prospectors have searched the area since the late 19th century and finds continued until the 1990ies (Ashwal 2001). At Buchwald’s time the locals made little use of metal detectors to prospect for Gibeon meteorites. This changed in the late 1970ies and 1980ies.

With the use of professional equipment also the mass distribution of the specimens recovered changed. Instead of few large masses many small specimens in the pound and kilo range were found. Unfortunately particularly these smaller finds distributed to museums and collectors lack precise find coordinates.

Gibeon meteorites today are widely distributed among museum and private collections. The material is valued not only for its beautiful etch pattern but also for its superior resistance to oxidation.

In 2004 Namibia passed a new National Heritage act and therewith placed an export ban on meteorites. Under these laws it is considered an offence to even uncover or move a Gibeon meteorite from its find location.

Gibeon specimens traded today among meteorite collectors and museums were usually exported from South Africa previous to the independency of Namibia and the current prohibition. Prices for Gibeon material have risen constantly since the export ban was established; from 50 $/kg and below for larger specimens in the 1970ies to 500 $/kg and above at present.

Ruins of the German colonial police station of Kub at the bank of the upper Fish River near Kalkrand, Hardap-region. Image courtesy of Dr.-Ing. Klaus Dierks

Field investigation at the site of the finds at present has ceased according to locals, and the current laws regrettably provide little encouragement for the local farmers to map and submit find locations and information on newly discovered meteorites to researchers. Despite the 2004 law, which even restricts any survey or investigation "for the purpose of finding […] a meteorite" (National Heritage Act 2004), it is to be hoped that Citron's expectations on the future research of the Gibeon meteorite strewnfield are fulfilled:

“A thorough field investigation of this area would undoubtly lead to the recovery of many additional tons of meteoritic material and the delineation of the boundaries of this enormous shower.” (Citron 1967)

Historic literature on the Gibeon meteorites from the author's collection

Literature

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Ashwal, L. D.: Korra Korrabes: A new, large H3 chondrite breccia from Namibia. In: Meteoritics & Planetary Science, vol. 36, no. 8, pp. 1027-1038 (2001)

Bajo, K. et al.: Noble Gases in a Gibeon Iron Meteorite Fragment Heavily Shielded to Cosmic Rays. In: 71st Annual Meeting of the Meteoritical Society, held July 28-August 1, 2008 in Matsue, Japan. Meteoritics and Planetary Science Supplement, Vol. 43, paper id. 5073

Berwerth, F.: Der Meteoreisenzwilling von Mukerop, Bezirk Gibeon, Deutsch-Südwest-Afrika. Extr. from: Sitzungsber. der kaiserl. Akademie der Wiss., vol. CXI, 1902, p.1ff.

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Khazanovich-Wulff, K.K.: A Consistent Spatial Position of the Kimberlite and Meteorite Fields Gibeon and Gross Brukkaros Structures (GB), Namibia: Random or Regular Pattern? In: Meteoritics & Planetary Science, vol. 36, Supplement, p.A97, 2001

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Petaev, M.I. et al.: Mineralogy and origin of brassy, sulfide-rich masses in the Gibeon IVA iron. In: 28th Annual Lunar and Planetary Science Conference, 1997, p. 093.

Petaev, M.I. et al.: Mineralogy of Sulfide-bearing Vugs in the Gibeon IVA Iron. In: 28th Annual Lunar and Planetary Science Conference, March 17-21, 1997, Houston, TX, p. 1095

Petaev, M.I. et al.: Cr-bearing Minerals in the Gibeon IVA Iron: Indicators of Sulfur and Oxygen Fugacities in the Parent Body. In: 28th Annual Lunar and Planetary Science Conference, March 17-21, 1997, Houston, TX, 1997, p.1091

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