Northwest Africa 15747 (NWA 15747)
(Northwest Africa)
Purchased: 2022 Oct
Classification: Carbonaceous chondrite (C2, ungrouped)
Physical characteristics: A single crusted stone.
Petrography: (J. Gattacceca, CEREGE) Chondrite with chondrules with average apparent diameter 590±270 (n=7) set in an abundant fine-grained iron-rich matrix (85 vol%). Some chondrules have fine grain dust rim, about 200 µm thick. Metal is present as blebs to 500 µm in the matrix, and inside chondrules. No CAI was observed. X-ray diffraction analyses over a ~2 cm2 area on a polished section (D. Borschnek, CEREGE) reveal the presence of phyllosicilates, as typically observed in type 2 chondrites using the same experimental setup.
Geochemistry: Olivine Fa13.1±11.2, range Fa0.5-30.2 (n=9), Cr2O3 in ferroan olivine 0.36±0.13 (n=6). Pyroxene Fs6.3Wo0.7Fs1.5Wo2.5. Defocused matrix analyses FeO 35.7 wt%, analytical totals 85.1 wt%.
Classification: Carbonaceous chondrite (C2-ungrouped). The type 2 designation is based on the presence of phyllosilicates. The high matrix abundance and chondrule size set this meteorite apart from CM2 chondrites.
Specimens: Type specimen at CEREGE. Main mass with Kuntz.