Northwest Africa 15515 (NWA 15515)

Morocco

Find: 2015

Classification: HED achondrite (Eucrite, polymict)

History: This meteorite was purchased by Luc Labenne in Agadir, Morocco, from a Moroccan dealer.

Physical characteristics: (T. Shisseh, R. Hewins, FSAC, MNHNP) Slices of this rock reveal a brecciated interior with rounded and angular clasts and mineral fragments embedded in a fine-grained matrix.

Petrography: (T. Shisseh, R. Hewins, B. Zanda, E. Jacquet, H. Chennaoui Aoudjehane, S. Pont, FSAC, MNHNP) Scanning electron microcopy examination of two polished sections of this rock shows basaltic and cumulative clasts set in a fragmental matrix. Both equilibrated and unequilibrated pyroxenes are present. The thickness of augite lamellae in equilibrated pyroxene ranges from 1 to 10 µm. Plagioclase laths in basaltic clasts are ~1 mm long and 100 µm in width. Plagioclase in cumulate clasts is up to 3 mm in size. The matrix encloses an impact spherule up to 2 mm in diameter. Silica grains with pyroxene rims are found. Minor mineral phases include silica, chromite, ulvöspinel, ilmenite.

Geochemistry: (T. Shisseh, R. Hewins, FSAC, MNHNP) Low-Ca pyroxene in cumulative clasts is En₆₃Fs₃₁Wo₆ (Fe/Mn=31.5; Mg# =67; n=1). Low-Ca pyroxene in basaltic clasts is En_43±6.6Fs_49±6.5Wo_8±3.8 (Fe/Mn=32; Mg# =47; n=16). High-Ca pyroxene is En_34±1.7Fs_41±4.7Wo_25±6.2 (n=5). Plagioclase is An_82-92) (n=8). Average TiO₂ and FeO contents in ilmenite are 53 wt% and 43.8 wt%, respectively (n=2).

Classification: (T. Shisseh, R. Hewins, FSAC, MNHNP) Polymict eucrite. This meteorite is composed of basaltic and cumulate eucrite lithologies.