Northwest Africa 14051 (NWA 14051)

(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 210±160 µm, n=40) set in an abundant fine-grained, iron-rich matrix (72 vol% from point coounting, n=290). Chondrules have fine-grained dust rims with radial cracks. Opaque minerals are metal, troilite, magnetite. No CAIs were observed.

Geochemistry: Olivine Fa_13.0±17.4, range Fa_0.6-33.7, Fa PMD = 108% (n=12). Cr₂O₃ in ferroan olivine 0.39±0.16 (n=8). Low-Ca pyroxene Fs_4.4±3.4Wo_3.2±2.1 (n=5). Defocused matrix analyses FeO = 33.6 wt%, analytical total 90.6 wt%. 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 234 mg bulk sample is δ¹⁷O=-0.907‰, δ¹⁸O=5.894‰ , Δ¹⁷O=-3.972‰ (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 distinguishes this meteorite from CM2 chondrites. The oxygen isotopic composition plots below the trend defined by CM chondrites. The high matrix abundance, chondrule size and oxygen isotopic composition distinguish this meteorite from CO3 chondrites.

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