Northwest Africa 13768 (NWA 13768)
Classification: HED achondrite (Howardite)
History: The meteorite was purchased from a dealer in Errachidia, Morocco.
Physical characteristics: Light grayish fragment partly covered by fusion crust.
Petrography: The meteorite displays a fresh light-grayish interior and is a polymict breccia composed of lithic and mineral clasts set into a fine-grained clastic matrix. Lithic clasts are basaltic, gabbroic, and dark impact melt clast up to 1.7 cm in size. Main minerals are up to 1 mm sized diogenetic orthopyroxene (about 15%), compositionally zoned low-Ca pyroxene, exsolved pyroxene and calcic plagioclase. Minor phases include silica, chromite, ilmenite, FeS, fayalitic olivine, and kamacite.
Geochemistry: diogenetic pyroxene: Fs30.0±0.6Wo5.5±0.5 (Fs29.1-30.7Wo5.1-6.4, FeO/MnO=23-27, n=7); zoned pyroxene: Fs38.7±6.8Wo10.8±4.0 (Fs24.7-46.1Wo4.5-16.0, FeO/MnO=24-26, n=7); eucritic low-Ca pyroxene host crystals to augite lamellae: Fs53.3±1.0Wo5.2±0.9 (Fs52.0-54.8Wo4.0-6.2, FeO/MnO=29-30, n=6); augite exsolution lamellae: Fs26.2±0.2Wo41.1±0.2 (Fs25.8-26.6Wo40.7-41.3, FeO/MnO=24-28, n=6); olivine: Fa76.5±0.1, FeO/MnO=40, n=2); calcic plagioclase: An87.5±5.4 (An75.4-90.3, n=6)
Place of purchase: Errachidia, Morocco
Date: P 2020
Mass (g): 1680
Shock stage: low
Weathering grade: low
Fayalite (mol%): 76.5
Ferrosilite (mol%): 30.0; 38.7; 53.3; 26.2
Wollastonite (mol%): 5.5; 10.8; 5.2; 41.1
Classifier: A. Greshake, MNB
Type spec mass (g): 27.2
Type spec location: MNB
Main mass: Tomasz Jakubowski
Comments: Submitted by Ansgar Greshake