Gourara 003        29°48.79’N, 2°56.66’E

Ghardaia, Algeria

Find: 2020

Classification: HED achondrite (Eucrite, monomict)

History: A single fusion-crusted broken stone weighing 3273 g was found by nomads in the desert outside the town of Hassi Gara, Algeria, in early 2020. Broken fragments were subsequently purchased from a Moroccan dealer in April and May 2020 by Oz Backman, Topher Spinnato, and Jason Bliss.

Physical characteristics: Fragments of the single broken stone display an extremely fresh, black glossy fusion crust. Certain fragments display radial flowlines, rollover lip, and regmaglypts. A slice of the interior reveals a brecciated sample with an assortment of light and dark clasts set in a finer-grained matrix.

Petrography: (D. Sheikh, FSU) Specimen is a monomict breccia consisting of eucrite lithic clasts exhibiting primarily diabasic textures (grain size 800 µm, up to 3 mm) set in a fine-grained clastic matrix of similar lithology with approximately 50% pyroxene, 45% plagioclase, 4% opaques, and 1% shock-melt veins. Mineral phases include pigeonite (most displaying exsolution lamellae of varying width; some inverted to orthopyroxene), augite (some exsolved from pigeonite), orthopyroxene, calcic plagioclase (display both polysynthetic and carlsbad twinning under cross-polarized light), ilmenite, chromite (some Ti-rich), and SiO₂-rich glass.

Geochemistry: Orthopyroxene (Fs_51.5±1.9Wo_4.9±0.7, range Fs_48.5-55.0Wo_3.6-5.7, FeO/MnO = 31±4, n=15), Pigeonite (Fs_50.7±1.3Wo_7.4±1.2, range Fs_47.9-53.3Wo_6.1-10.8, FeO/MnO = 32±4, n=26), Augite (Fs_27.7±3.4Wo_37.7±4.6, range Fs_21.3-33.9Wo_27.1-42.3, FeO/MnO = 28±4, n=8), Calcic Plagioclase (An_91.6±1.2, range An_88.7-94.2, n=42).

Classification: HED Achondrite (Eucrite, monomict breccia).

Specimens: 20.21 g at UNM; 430 g with Oz Backman; 2714 g with Topher Spinnato; 129 g with Jason Bliss.