Northwest Africa 13167 (NWA 13167)

(Northwest Africa)

Purchased: 2019

Classification: Carbonaceous chondrite (C2, ungrouped)

History: The meteorite was purchased from a meteorite dealer in Morocco.

Physical characteristics: Five black individuals partly covered with fusion crust.

Petrography: The meteorite a brecciated matrix-dominated carbonaceous chondrite with chondrules (mean diameter about 300 μm), mineral fragments, and few CAIs. Most of the components are surrounded by fine-grained dust rims. The matrix is highly porous and composed of Ca-carbonates, phyllosilicates with fibrous and flaky appearance, and Fe-sulfides. Some FeNi metal grains are present mostly as inclusions in forsteritic olivine.

Geochemistry: Mean values of defocused matrix analyses (beam diameter 10 µm; all wt%; N=25): SiO₂: 24.1, TiO₂: 0.03, Na₂O: 0.46, Cr₂O₃: 0.29, MgO: 13.9, MnO: 0.16, FeO: 31.2, Al₂O₃: 2.50, NiO: 2.10, P₂O₅: 0.34, S: 4.6, Total: 79.69; Oxygen isotopes (K. Ziegler, UNM): 6 acid-washed fragments analyzed by laser fluorination gave: δ¹⁸O=-6.769, -2.952, -1.991, 1.322, -2.345, -3.978; δ¹⁷O=-10.566, -7.481, -6.795, -4.079, -6.747, -8.036; Δ¹⁷O= -6.992, -5.922, -5.744, -4.777, -5.509, -5.936 (all per mil)

Classification: C2 due to petrography and presence of phyllosilicates and carbonates. Ungrouped according to oxygen isotopic composition which is incompatible with CM.