Hassi Khebi 001 Carbonaceous Chondrite C3 ungrouped 0.338g

Hassi Khebi 001        29°09’28.3″N, 4°55’43.3″W

Tindouf, Algeria

Purchased: 2022

Classification: Carbonaceous chondrite (C3, ungrouped)

History: Purchased by Matthew Stream from an Algerian meteorite dealer in August 2022. Found approximately 15 km southeast of Hassi Khébi in Tindouf Province, Algeria.

Physical characteristics: Dark gray/black fusion-crusted exterior, saw cut surface reveals scattered well-formed chondrules set in a black matrix that makes up over 50% of this meteorite. Some of the chondrules appear to have orange iron-staining. Rare small CAIs are visible.

Petrography: (C. Agee and M. Spilde, UNM) Electron microprobe examination reveals a fine-grained matrix that gives slightly low microprobe totals (~95%) consistent with the absence of significant hydrous phases. Most chondrules are porphyritic type I with predominantly forsteritic olivines and enstatitic pyroxenes. Apparent mean chondrule diameter is 275±227 μm (n=50). Kamacite and Fe-Ni sulfide are the dominant opaque phases. Cr-magnetite was not detected. Vesicular fusion crust is 200-300 µm thick.

Geochemistry: (M. Spilde and C. Agee, UNM) Type I chondrule olivine Fa_1.3±1.4, Cr₂O₃=0.34±0.16 (wt%) n=24; low-Ca pyroxene Fs_1.6±0.8Wo_1.6±1.5, n=9; matrix (20 μm defocused microprobe beam) SiO₂=31.5±5.3, TiO₂=0.32±0.66, Cr₂O₃=0.43±0.14, Al₂O₃=4.4±3.6, FeO=29.6±9.7, MgO=15.7±3.7, CaO=3.0±3.4, NiO=1.6±0.3, MnO=0.21±0.07, Na₂O=0.18±0.05, K₂O=0.27±0.15, SO3=7.3±3.6 (all wt%), n=7., with total around 95 wt% not consistent with significant hydrous phases being present. Fusion crust, proxy from bulk composition (20 µm defocused microprobe beam) SiO₂=43.5±2.5, TiO₂=0.17±0.01, Cr₂O₃=0.58±0.04, Al₂O₃=4.2±0.5, FeO=19.5±4.0, MgO=28.2±2.5, CaO=3.1±0.3, NiO=0.10±0.07, MnO=0.35±0.01, Na₂O=0.83±0.12, K₂O=0.07±0.01 (all wt%), n=7. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ¹⁷O=-6.509,-7.235,-9.497; δ¹⁸O=-1.497, -2.483, -5.165 (all ‰).

Classification: Carbonaceous chondrite ungrouped (C3). Oxygen isotopic compositions are significantly displaced below the CCAM indicating ungrouped carbonaceous chondrite. Type 3 based on a predominantly anhydrous matrix and Cr₂O₃ content of olivine.

Specimens: 20 g on deposit at UNM, Matthew Stream holds the main mass.