Northwest Africa 11732 (NWA 11732)

(Northwest Africa)

Purchased: 2017

Classification: Carbonaceous chondrite (CM2.0)

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

Physical characteristics: Small black individual with some fusion crust.

Petrography: The meteorite is a brecciated carbonaceous chondrite composed of chondrule, mineral and CAI polymorphs set into a fine-grained matrix of phyllosilicates (as indicated by fibrous appearance), carbonates and sulfides including up to 400 μm long needles of Ni-bearing pyrrhotite. Carbonates are almost pure calcites and Mg-Mn-Fe-rich varieties. The hydrous and porous nature of the matrix is also proven by low analytical totals of defocused (10 μm beam diameter) electron microprobe analyses. Many components are surrounded by flaky phyllosilicates apparently replacing former dust rims. No anhydrous silicates have been found.

Geochemistry: Mean values of defocused (10 μm beam diameter) matrix analyses (all wt%; N=27): SiO₂: 27.0, TiO₂: 0.09; Na₂O: 0.11; Cr₂O₃: 0.41, MgO: 19.8, MnO: 0.18, CaO: 0.25, FeO: 21.7, Al₂O₃: 2.29, NiO: 0.79, P₂O₅: 0.03, S: 0.36, Total: 73.01

Classification: CM2.0. Subtype based on the absence of anhydrous silicates.