Sierra Gorda 009        22°30.10’S, 69°08.20’W

Antofagasta, Chile

Find: 2017 Oct 21

Classification: Ungrouped chondrite

History: Three pieces (30 g, 70 g, and 140 g) of one meteorite were found in the the desert by Mr. T. V. Kryachko, Mr. M. E. Nepomiluev, and an anonymous finder.

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

Petrography: M. A. Ivanova (Vernad) Meteorite has chondritic texture and consists of FeNi-metal (22 -25 vol%), chondrules, and their fragments; matrix is absent. Chondrules, up to 2 mm, are PP, BO, POP, SiO₂-bearing and Al-rich with clear bounaries; PP chondrules are dominant; the main minerals are pyroxene, Fe,Ni-metal, olivine and sulfides (troilite and daubreelite), schreibersite; accessory minerals are silica, Mg-chromite, anorthite, spinel, graphite and PGE-metal nuggets.

Geochemistry: Mineral compositions and geochemistry: M. A. Ivanova (Vernad), V. V. Kozlov (Oxford Instruments OM & Gatan Inc., Moscow Office) Olivine: Fa_0.47±0.10 (N=74), orthopyroxene: Fs_1.42±0.39Wo_0.88±0.63 (N=42), (N=42), FeO-rich Opx: Fs_9.33-32.48Wo_0.23-4.74; diopside: Fs_1.34±0.57Wo_47.32±2.31; plagioclase varies in composition: An _32.28-95.04Ab_4.96-65.99; mesostasis in chondrules is enriched in K₂O (up to 9.18 wt%) and TiO₂ (up to 6.53 wt%); kamacite contains 5.07 wt% Ni, 0.43 wt% Co, Co/Ni - 0.09, Si and Cr are below detection (<0.03 wt%); taenite: Ni -32.3 wt%, Co - 0.25 wt% ; troilite is enriched in Cr (up to 2.4 wt%); MgO-chromite is almost pure MgO-end member. Oxygen isotopic compositions: (OU) δ¹⁷O 3.763, 3.736; δ¹⁸O 6.263, 6.169; Δ¹⁷O 0.506, 0.528 permil.

Classification: ungrouped Fe,Ni-metal-rich chondrite with affinities to "G-chondrites" (GRO 95551 and NWA 5492, Weisberg et al., 2015) in texture and mineral chemistry. Oxygen isotopic compositions are between those of ordinary and enstatite chondrites.

Specimens: 3 pieces of the meteorite (6.3, 16.2, and 18 g), polished and thin sections are deposited in Vernad. Anonymous finder, Mt. M. E. Nepomiluev ([email protected]), and Mt. T. V. Kryachko ([email protected]) hold the main mass of the meteorite.