Sierra Gorda 013        22°30.96’S, 69°07.51’W

Antofagasta, Chile

Find: 2018 Oct 24

Classification: Carbonaceous chondrite (CBa)

History: 8 pieces of one meteorite were found in the the desert by Mr. T. V. Kryachko.

Physical characteristics: all samples of the meteorite have a brown fusion crust.

Petrography: M. A. Ivanova, C. A. Lorenz (Vernad) Meteorite contains two lithologies - one lithology consists of Fe,Ni-metal nodules(~80 vol%), up to 0.5 cm, and POP and BO chondrules, and their fragments up to 0.4 cm, matrix is absent; minerals are olivine, pyroxene, anorthite, Fe,Ni-metal, daubreelite, schreibersite and chromite. The second lithology consists of Fe,Ni-metal (~50 %) and silicates (~50%), with relic chondrules; many fractures filled by products of Fe,Ni oxidation are crossing the lithology. In this lithology, sulfides and schreibersite are absent. Shock stage is S2, but several fragments have stage S3-4 and contain melt pockets enclosing tiny blebbs of Fe,Ni-metal.

Geochemistry: Mineral compositions and geochemistry: M. A. Ivanova, C. A. Lorenz (Vernad) Olivine: Fa_2.2±0.3 (N=53), orthopyroxene: Fs_3.4±0.3Wo_1.6±0.3 (N=75), clinopyroxene is represented by diopside: Fs_1.9±0.4Wo_45.7±0.5; plagioclase has a constant composition: An_95.8±0.2Ab_4.0±0.3; Fe,Ni-metal is not zoned, kamacite contains 6.90 wt% of Ni, 0.39 wt% wt% of Co; daubreelite is enriched in V (up to 2.0 wt%); chromite contains up to 15.0 wt% of Al₂O₃ and 18.0 Wt% of MgO . Oxygen isotopic compositions: (OU) δ¹⁷O -1.889, -1.9; δ¹⁸O 0.65, 0.59; Δ¹⁷O -2.226, -2.206 permil.

Classification: bencubbinite. Based on the texture, FeNi metal and chondrule sizes, their abundances, mineral compositions and bulk oxygen isotopic composition, the meteorite belongs to type CBa.

Specimens: a piece of the meteorite (99.3 g), 2 polished thin sections are deposited in Vernad. Mt. T. V. Kryachko ([email protected]) holds the main mass of the meteorite.