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 Fa_13.1±11.2, range Fa_0.5-30.2 (n=9), Cr₂O₃ in ferroan olivine 0.36±0.13 (n=6). Pyroxene Fs_6.3Wo_0.7Fs_1.5Wo_2.5. 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.