In Collection : 0.6 gram slice

This write-up was originally printed in Meteoritical Bulletin 83:
©Meteoritical Society

Dar al Gani 476
Libya
Found 1998 May 1
Martian basalt (shergottite)

A brownish stone weighing 2015 g was found in Dar al Gani, Sahara. Mineralogy and classification (J. Zipfel and P. Scherer, MPI): fusion crust absent; meteorite has a porphyritic texture, consisting of olivine embedded in a fine-grained matrix of clinopyroxene laths (pigeonite and minor augite) and interstitial feldspathic glass; mineral abundances similar to EET 79001 lithology A; Fe-sulfide, Ti-rich chromites, ilmenite and chromite present; shock features include twinning and fracturing of clinopyroxene, mosaicism of some olivine, and plagioclase converted to feldspathic glass; impact-melt pockets abundant; extensive terrestrial weathering resulted in carbonate veins crosscutting the meteorite along grain boundaries and cracks; bulk chemistry intermediate between basaltic and lherzolitic shergottites, with a high bulk Mg/(Mg + Fe), high concentrations of siderophile elements, relatively low abundances of heavy rare earth elements (HREE), and a strong light rare earth element (LREE) depletion; exposure age 1.1 ± 0.2 Ma; 36Ar/132Xe and 84Kr/132Xe typical of Martian meteorites, and 129Xe/132Xe similar to Chassigny. Oxygen isotopes (I. Franchi, OU): d18O = 4.57, d17O = 2.69‰ rel. SMOW (D17O = 0.317). The petrography, mineralogy, and noble gas chemistry of DaG 476 and DaG 489 are very similar, and the two are likely paired (L. Folco, MNA-SI, and J. Zipfel and L. Schultz, MPI). Specimens: type specimen, several grams, and one polished section, MPI; main mass with anonymous finder.