Northwest Africa 14740 (NWA 14740)

(Northwest Africa)

Purchased: 2021

Classification: Carbonaceous chondrite (C3, ungrouped)

History: Purchased jointly by Juan Poblador and Roger Jones in 2021 from an Algerian dealer.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL; L. Garvie, ASU) Relatively small, well-formed chondrules (apparent diameter 310±280 µm, N = 26) accompanied by zoned mineral grains, AOA and rare very small, amoeboid, very fine grained CAI are set in a black ultra fine-grained matrix (~60 vol.%). Accessory phases detected by electron microprobe analysis include troilite, pentlandite, kamacite (as inclusions in chondrule olivine only) and calcite. No phyllosilicates were detected by powder X-ray diffraction analysis.

Geochemistry: Olivine (Fa_23.1±23.8, range Fa_0.9-58.1, N = 8), low-Ca pyroxene (Fs_1.1±0.5Wo_2.8±2.6, range Fs_0.7-1.4Wo_0.9-4.6, N = 2), subcalcic augite (Fs_0.8Wo_30.3). Oxygen isotopes (C. Sonzogni, J. Gattacceca, CEREGE): analysis of a 1.5 mm powdered sample by laser fluorination gave δ¹⁷O 1.41, δ¹⁸O 8.68, Δ¹⁷O -3.16 (for a TFL slope of 0.526), all per mil.

Classification: Carbonaceous chondrite (Type 3, ungrouped). Potentially paired with NWA 14139, NWA 14179 and other recently recovered ungrouped C3 chondrite specimens based on similarities in texture, mineralogy and especially oxygen isotopic composition.

Specimens: 22.0 g including one polished thin section at UWB; remainder equally with Mr. J. Poblador and Mr. R. Jones.