Northwest Africa 5731                                                                                                                                     
Erfoud, Morocco
Found December 2008
Ordinary chondrite (LL3.2)

History:  Purchased in Morocco in December 2008 by PThomas.
Physical characteristics: One stone weighing 241.04 g.
Petrography: (N. Chaumard and B. Devouard, UBP) Chondrules size range from 50 mm to 1.2 mm. CAI are small but one type A is larger than 1.5 mm. Fe-diffusion is visible at borders and cracks in olivine grains in type I chondrules. Matrix is composed of dominant fine grains of fayalite and few forsteritics crystals up to 50 mm.
Mineral compositions and geochemistry: Olivine in matrix are Fa62.9. Olivine mean composition in type I chondrules, Fa3.5 (range Fa0.7–Fa7.4); mean low-Ca pyroxene, Fs4.6 (range Fs1.5–Fs7.7). In type II chondrules, mean olivine, Fa28.6 (range Fa13.5–Fa50.1); mean pyroxene, Fs20.3+2.1. Analyses of Cr2O3 in olivines from type II chondrules yield an average of 0.11 wt% with standard deviation s = 0.05%. In olivines from type IA chondrules FeO = 2.3 + 0.9 wt% and CaO = 0.35 + 0.06 wt%.