Northwest Africa 15518 (NWA 15518)

Morocco

Find: 2015

Classification: HED achondrite (Eucrite, polymict)

History: This meteorite was purchased by Luc Labenne in Laâyoune, Morocco, from an anonymous Moroccan dealer.

Petrography: (T. Shisseh, R. Hewins, B. Zanda, E. Jacquet, H. Chennaoui Aoudjehane, S. Pont, FSAC, MNHNP) Scanning electron mosaic map of this rock reveals a brecciated texture, with clasts exhibiting a wide range of sizes and textures, embedded in a matrix composed of glass and mineral fragments. The major mineral phases are pyroxene and plagioclase. Pyroxene is equilibrated, and contains exsolution lamellae of augite. Plagioclase is generally clear, but some has tiny inclusions of pyroxene, silica and oxides following crystallographic directions. Schlieren and pools of melted plagioclase are observed in the matrix. Minor phases are silica, chromite, ulvöspinel, ilmenite, troilite and olivine. Shock veins are crossing the clasts and the matrix.

Geochemistry: (T. Shisseh, R. Hewins, FSAC, MNHNP) Low-Ca pyroxene composition is En₄₉Fs₄₉Wo₂ (Fe/Mn=32; Mg# =50; n=1) and En_42±0.7Fs_56±1Wo_2±0.2 (Fe/Mn=29±1.8; Mg# =43; n=3). High-Ca pyroxene is s En_33±0.3Fs_23±1.5Wo_44±1.1 (n=3). Plagioclase is An_88.5-92.5Or_0.24-0.25 (n=4). Ilmenite has 57 wt% TiO₂ and 43 wt% FeO (n=1).

Classification: (T. Shisseh, R. Hewins, FSAC, MNHNP) Polymict eucrite.