NWA 11754 Ureilite
Northwest Africa 11754 (NWA 11754)
Purchased: 2017 Jul
Petrography: (K. Metzler, IfP) Coarse-grained ultramafic rock with metamorphic texture (~120° triple junctions), consisting of olivine, low-Ca pyroxene, and Ca-pyroxene grains with sizes up to ~3 mm. Reverse zoning of olivine with Mg-rich zones at the margins and along cracks can be observed. Metal is concentrated along grain boundaries and cracks and mostly oxidized by terrestrial weathering.
Geochemistry: Mineral compositions and geochemistry: Olivine cores (n=4): Fa11.4±0.7; Olivine rims (n=3): Fa6.6±0.3. Low-Ca pyroxene grains (n=9): Fs10.7±0.2Wo4.9±0.2. Ca-pyroxene grains (n=12): Fs6.6±0.2Wo36.2.±0.2. The concentration of Cr2O3 in olivine and pyroxene is 0.5 wt% and 1.1 wt%, respectively.