Northwest Africa 8559 (NWA 8559)

(Northwest Africa)

Purchased: 2013

Classification: HED achondrite (Howardite)

History: Purchased by Brahim Tahiri from a Moroccan hunter and sent to his partner Sean Tutorow for classification, April, 2013.

Physical characteristics: Single stone. Smooth brown weathered exterior. Saw cut reveals breccia with white and dark gray fragmental clasts, also lithic clasts set in a medium-gray groundmass.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows a fragmental to cataclastic breccia with equilibrated (exsolution lamellae) and unequilibrated (igneous zoned) pyroxenes throughout. Silica, troilite, ilmenite, chromite present. Approximately 20% of this meteorite is diogenitic, ~30% is basaltic eucrite, and ~50% is cumulate eucrite.

Geochemistry: (C. Agee and N. Muttik, UNM) Diogenite minerals: low-Ca pyroxene Fs_26.4±3.0Wo_2.5±1.0, Fe/Mn=28±1, plagioclase An_94.6±0.5, n=2. Basaltic eucrite minerals: low-Ca pyroxene Fs_58.1±5.0Wo_5.9±3.1, Fe/Mn=32±1, n=6; high-Ca pyroxene Fs_35.9±9.2Wo_34.1±13.1, Fe/Mn=33±2, n=3; plagioclase An_85.8, n=1. Cumulate eucrite minerals: low-Ca pyroxene Fs_43.6±5.3Wo_6.7±3.7, Fe/Mn=32±2, n=9; plagioclase An_91.9±0.4, n=2.

Classification: Achondrite (howardite)

Specimens: 20.7 g including a probe mount on deposit at UNM, Sean Tutorow holds the main mass.