Northwest Africa 10645 (NWA 10645)

(Northwest Africa)

Purchased: 2016

Classification: Martian meteorite (Nakhlite)

History: Purchased by Dustin Dickens, February 2016, from a Moroccan dealer.

Physical characteristics: The exterior is partially covered by black fusion crust. Freshly broken surfaces reveal a mixture of mm-sized dark-green pyroxene grains and interstitial cream-colored feldspar.

Petrography: (C. Agee, UNM) This meteorite has an ophitic texture consisting of 75% augite, 15% feldspar, and 5% olivine. Some augite crystals are prismatic and up to 2 mm in length. There are two feldspars present, oligoclase and alkali feldspar, no maskelynite was observed; feldspar commonly occupies interstices between augite grains. Augites show igneous zoning with Fs-rich rims, olivines are fayalitic and fairly uniform in composition. Apatite, ilmenite, and titanomagnetite were observed.

Geochemistry: (C. Agee and M. Spilde, UNM) Olivine Fa_88.1±0.8, Fe/Mn=41±1, n=5; augite Fs_31.9±10.2Wo_38.9±2.1, range Fs_24.1-48.9Wo_33.3-40.5, Fe/Mn=35±2, n=10; plagioclase An_22.9±2.7Ab_73.0±3.0Or_4.1±0.6, n=4; alkali feldspar An_3.3Ab_40.4Or_56.2, n=1.

Classification: Martian (nakhlite). This is a martian meteorite based Fe/Mn of augite and olivine, and on the composition of the plagioclase. It is a nakhlite based on the high percentage of augite present. Paired with NWA 10153.

Specimens: 2.5 g including a probe mount on deposit at UNM; Dustin Dickens holds the main mass.