Northwest Africa 14052 (NWA 14052)

(Northwest Africa)

Purchased: 2020

Classification: Carbonaceous chondrite (C3, ungrouped)

History: Bought in Morocco

Physical characteristics: One crusted stone. Cut face reveals a dark interior with small chondrules.

Petrography: (J. Gattacceca, CEREGE) Chondrules (average apparent diameter 240±200 µm, n=31) and chondrule fragments set in an abundant fine-grained, iron-rich matrix (75 vol% by point counting, n=240). Opaque minerals are metal (as small spheres in the silicates) and troilite. No CAIs were observed.

Geochemistry: Olivine Fa_14.0±16.2, range Fa_1.0-42.4 (n=8). Cr₂O₃ in ferroan olivine 0.49±0.10 (n=7). Low-Ca pyroxene Fs_1.8Wo_1.0 (n=1). Defocused matrix analyses FeO = 36.3±2.4 wt%, analytical total 94.5±1.1 wt% (n=4). XRD of a powdered sample (D. Borschnek, CEREGE) does not reveal the presence of hydrous phases (serpentine, tochilinite) typically observed in type 2 chondrites using the same experimental setup. Oxygen isotopic composition (J. Gattacceca, C. Sonzogni, CEREGE) from analysis of one acid-washed 1.5 mg aliquot of a powdered 119 mg bulk sample is δ¹⁷O=-3.30‰, δ¹⁸O=2.739‰ , Δ¹⁷O=-4.724‰ (slope 0.52, analytical uncertainties 0.08‰, 0.12‰, 0.03‰ respectively),

Classification: Carbonaceous chondrite (C3-ung). Carbonaceous chondrite based on petrography and oxygen isotopes. Type 3 based on the unequilibrated silicates and absence of phyllosilicates. The absence of phyllosilicates and the oxygen isotopic composition distinguish this meteorite from CM2 chondrites. The high matrix abundance and chondrule size distinguish it from CO3 chondrites.

Specimens: Type specimen at CEREGE. Main mass with Labenne.