Dar al Gani 476 Mars Meteorite

 
 

click images to enlarge:

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Specimen shown is a full slice weighing 37 grams and measures 87mm x 79mm by 2.5mm thick at widest points.

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Complete specimen weighting 2016 grams.

 
 

Found May 1, 1998
27 21.16' N., 16 12.04' E.

"Lucky 13" was found in the Libyan Sahara desert, the first Martian meteorite recovered from a hot desert environment. The brown, loaf-shaped mass weighing 2,015g was analyzed and classified at Germany's Max Planck Institute for Chemistry in Mainz. This is very appropriate since this institute also developed the APXS instrument used during the Mars Pathfinder Mission aboard the Sojourner Rover to analyze surface rock compositions.

Comparisons with Viking inert gas measurements clearly identify this meteorite as Martian. In addition, results from chemical, mineralogical, petrographic, and oxygen isotopic studies indicate that this is a new Martian meteorite. It was ejected from Mars about 1.1 m.y. ago, a uniquely timed event among all Martian specimens (but close to EET79001 with an ejection age of 0.82 (+/-0.2) m.y). Its estimated preatmospheric radius was ~20 cm. Through thousands of years of desert exposure (85 +/-50 k.y.), this meteorite has completely lost its fusion crust and developed cracks and veins that are filled with carbonate and other terrestrial weathering products.

The shergottite group was divided into two distinct subgroups: the basalt subgroup including those with a volcanic origin and consisting primarily of the clinopyroxenes pigeonite and augite, and the lherzolite or harzburgite subgroup including those with a plutonic origin and consisting primarily of olivine, chromite, and orthopyroxene. The bulk chemistry of DG 476 is intermediate between the basaltic and lherzolitic subgroups of shergottites. It contains olivine embedded in a fine-grained matrix composed mostly of Ca-poor pigeonite with minor Ca-rich augite. Shock features present include twinning of clinopyroxene, mosaicism of olivine, and plagioclase converted to feldspathic glass. Impact melt pockets are abundant.

 
 

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