Northwest Africa 13143 (NWA 13143)

Morocco

Find: 2018

Classification: HED achondrite (Howardite)

Physical characteristics: Crusted stone. Cut surface reveals a light-gray interior with subrounded whitish clasts with size up to 1 cm, and more angular chondritic black clasts up to 1 cm.

Petrography: (J. Gattacceca, CEREGE) Mineral clasts (to 500 μm) set in a clastic matrix. Main minerals are plagioclase and pyroxene (some exsolved). Pyroxene of diogenitic and eucritic composition are found approximately in equal proportions. Other minerals: ilmenite, chromite (to 200 μm), silica polymorph (to 200 μm), troilite, metal. Contains a 5 mm × 5 mm chondritic clast with small chondrules set in an abundant, fine-grained, iron-rich, phyllosilicate-rich matrix containg sulfide and magnetite.

Geochemistry: Diogenitic low-Ca pyroxene Fs_29.4±2.13Wo_2.7±1.0 (n=4). Eucritic low-Ca pyroxene Fs_54.6±7.0Wo_2.0±0.3 (n=3). Ca-pyroxene Fs_30.2±5.8Wo_28.0±9.4 (n=3). Overall pyroxene FeO/MnO=31.5±2.4. Two Mg-rich pyroxene were analyzed with Fs_13.8Wo_1.0 and Fs_14.2Wo_1.0, FeO/MnO=25.8. Plagioclase An_92.3±1.3Ab_7.4±1.3Or_0.3±0.1 (n=5). Chondritic clast: Olivine Fa_21.7±12.2 (range Fa_2.1-32.2), Cr₂O₃ 0.45±0.03 wt% (n=4), low-Ca pyroxene Fs_1.6±0.4Wo_1.1±0.2 (n=3). Analyses of a 50 μm × 50 μm matrix area in the chondritic clast gives an analytical total of 80.3 wt%, and FeO 28.6 wt%.

Classification: Achondrite (howardite). Contains a cm-sized CM2-like clast.

Specimens: Type specimen at CEREGE. Main mass with George Penneff