Northwest Africa 7387 (NWA 7387)

(Northwest Africa)

Purchased: 2012

Classification: Martian meteorite (Shergottite)

History: Purchased by Giorgio Tomelleri in Erfoud, Morocco.

Physical characteristics: The sample is covered with a black fusion crust.

Petrography: (V. Moggi Cecchi, G. Pratesi, S. Caporali, MSP): Cumulate, fine-grained, porphyritic texture consisting of a few large rounded and zoned phenocrysts of brown olivine up to 1200 μm, set in a fine-grained basaltic groundmass of twinned, tabular pyroxene crystals 90 to 2100 μm wide and 120 to 780 μm long. These crystals are surrounded by interstitial glassy matrix, dominated by maskelynite. Pyroxene is primarily pigeonite with subordinate enstatite. Other minerals are chromite, titanian chromite and ilmenite, up to 110 μm, merrillite, and rare pyrrhotite grains up to 40 μm in size. Shock features include strong mosaicism and planar deformation in olivine, undulose extinction and twinning in pyroxene.

Geochemistry: Olivine Fa_40.45 (mean of 26 analyses; FeO/MnO = 50.3); orthopyroxene (Fs_29.46En_60.87Wo_9.87; FeO/MnO = 30.9); pigeonite (Fs_18.79En_48.09Wo_33.13; FeO/MnO = 32.5-46.5). Maskelynite glass (An_46.34.15Or_2.96). Oxygen isotopes: (I.Franchi, R.Greenwood, OU) δ¹⁷O = 2.68, δ¹⁸O = 4.54, and Δ¹⁷O = 0.322 all per mil.

Classification: Martian (Shergottite)

Specimens: 20.13 g plus one polished thin section and a block are on deposit at MSP (MSP 5203). Tomelleri holds the main mass.