Dar al Gani 489

Libya

Found 1997

Martian basalt (shergottite)

A dark-brown stone of 2146 g was found in Dar al Gani. Mineralogy and classification (L. Folco and B. Anselmi, MNA-SI): devoid of fusion crust; porphyritic basaltic texture consisting of millimeter-sized phenocrysts of brown olivine (Fo_61–78, Mn/Fe = 0.021–0.025 atomic) set in a more fine grained matrix of pigeonite laths (En_57–72 Wo_5–15, Mn/Fe = 0.030–0.038 atomic) and interstitial feldspathic glass (An_56–67Ab_33–43); minor mineral components include augite, chromite, Ti-rich chromite, ilmenite, merrillite and pyrrhotite; texture, mineral modes and chemistry close to EETA79001 lithology A; shock deformation features include twinning in pigeonite, strong mosaicism and planar deformation features in olivine, and abundant impact-melt pockets and veinlets; pervasive veins filled in by calcite are due to terrestrial weathering. Oxygen isotopes (A. S. Sexton and I. A. Franchi, OU): d¹⁷O = 2.895, d¹⁸O = 4.980, and D¹⁷O = 0.305‰. 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: main mass with anonymous finder, 34.9 g; two polished thin sections, MNA-SI.