Northwest Africa 11408 (NWA 11408)

Morocco

Purchased: February 2013

Classification: Ureilite

History: Purchased from Moroccan meteorite dealer in 2013.

Physical characteristics: Physical Characteristics: Single stone, black rough irregular exterior. Saw cut shows mostly dark grains with a few exhibiting greater light reflectance. Stone was difficult to cut.

Petrography: (K. Domanik and F. Stephan, UAz) Microprobe examination of a polished mount shows approx. 45% olivine, 45% pigeonite, and 8% low-Ca pyroxene, all with an average grain size of approx. 800 - 1000 μm. Fe-Ni veins, now mostly oxidized by desert weathering, occupy grain boundaries and also crosscut some grains. The veins contain numerous, irregularly shaped patches of graphite, partially altered to diamond, mainly 50-200 μm in length but with a few up to 1000 μm. Olivine grains in contact with metal veins or diamond commonly display Mg-rich alteration rims (70-300 μm) containing small (<2 μm), metal blebs either randomly distributed or in linear arrays. Pigeonite and low-Ca pyroxene occasionally show narrow patches of Mg-rich pyroxene along contacts with metal veins or diamond.

Geochemistry: Mineral compositions and geochemistry: (K. Domanik and F. Stephan, UAz) Olivine cores Fa_10.3±0.6, Fe/Mn=22.5±2.7, Cr₂O₃=0.52±0.04 wt%, n=22; olivine rims Fa_1.4±1.0, Fe/Mn=3.2±1.7, Cr₂O₃=0.34±0.15 wt%, n=7; pigeonite Fs_9.7±0.2 Wo_8.6±0.1, Fe/Mn=14.4±1.0, Cr₂O₃=0.91±0.06 wt%, n=25; low-Ca pyroxene Fs_9.5±0.4Wo_4.9±0.1, Fe/Mn=15.7±1.8, Cr₂O₃=0.88±0.07 wt%, n=19; pyroxene rims Fs_0.9±0.2Wo_2.8±1.9, Fe/Mn=1.6±0.3, Cr₂O₃=0.29±0.09, n=7.

Classification: Achondrite (ureilite)

Specimens: 14.6 g including probe mount on deposit at UAz, Fredric Stephan holds the main mass.