Hassi el Biod 001 (HeB 001)        28°46’16.10"N, 05°30’10.00"E

Ouargla, Algeria

Purchased: 2020 Jan 2

Classification: HED achondrite (Diogenite, anomalous)

History: The meteorite was found by a nomad named Abo Zaid on January 2, 2020, in the great Sahara south of the village of Wargla, Algeria, and subsequently purchased by the main mass holder, Said Yousfi.

Physical characteristics: Light-brownish rock with very minor fusion crust.

Petrography: Unbrecciated ultramafic rock displaying a cumulate texture of up to 0.6 mm sized low-Ca pyroxene poikilitically enclosing rounded to subrounded olivine grains 20 to 400 µm in size. Most regions are pyroxene-dominated while few contain abundant clustered olivine grains. Pyroxene is compositionally zoned, i.e., exhibits Mg-rich cores and Fe-rich rims. Olivine grains are compositionally homogeneous but of four distinct compositions varying in Fe/Mg ratios. Many olivine grains show outer rims of symplectic intergrowth of chromite and silica. Plagioclase is a minor component typically occurring interstitial to pyroxene and olivine and is of highly variable composition. Opaques include Ti-poor zoned chromite, troilite blebs, and kamacite often intergrown with FeS.

Geochemistry: low-Ca pyroxene: Fs_23.7±2.3Wo_2.8±1.2 (Fs_17.7-28.8Wo_1.8-4.8, FeO/MnO=22-32, n=39); predominant olivine: Fa_28.9±0.2 (Fa_28.6-29.1, FeO/MnO=41±2, n=22); Fe-rich olivine: Fa_31.0±0.1 (Fa_30.8-31.2, FeO/MnO=40±2, n=5); intermediate olivine: Fa_25.6±0.1 (Fa_25.4-25.8, FeO/MnO=43±2, n=5); Fe-poorer olivine: Fa_24.1±0.2 (Fa_23.9-24.3, FeO/MnO=42±4, n=5); plagioclase: An_84.5±4.1Ab_14.9±3.9Or_0.5±0.2 (An_76.2-91.3Ab_8.4-22.5Or_0.3-1.4, n=19); chromite: Cr₂O₃ 45.22-52.41, TiO₂ 0.84-1.24, Al₂O₃ 14.31-20.17, MgO 5.82-6.91 (all in wt%); Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave: δ¹⁸O=3.816, 3.852, 3.830; δ¹⁷O=1.734, 1.753, 1.748; Δ¹⁷O= -0.280, -0.280, -0.274 (all per mil)

Classification: Achondrite (diogenite-anomalous, harzburgitic). The anomalous designation comes from the texture (pronounced cumulate texture of orthopyroxene poikilitically enclosing rounded olivine), and the oxygen isotopic composition that is apart from typical diogenites.