HASSI EL BIOD 002

Pallasite, ungrouped
standby for hassi el biod 002 photo
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Purchased 2021
28° 37' 42" N., 4° 43' 39" E.

Five individual masses with a combined weight of 10 kg were found in the Sahara Desert near the southwest tip of Ouargla Province in Algeria (Google Earth image), and these were subsequently purchased by M. Lyon. A type sample was submitted to the University of New Mexico's Institute of Meteoritics for analysis and classification (A. Ross and C. Agee; K. Ziegler, oxygen isotopes), and Hassi el Biod 002 was classified as an ungrouped pallasite.

The HeB 002 pallasite is composed of angular red-orange olivines (38 vol%) embedded in an FeNi-metal host (60 vol%), along with minor troilite (2 vol%). Other minor and accessory mineral phases commonly present in other pallasites were not observed in the classification analysis. The meteorite experienced low shock and exhibits moderate terrestrial weathering.

Hassi el Biod 002 and the Vermillion pallasite grouplet (Vermillion, Choteau, and Y-8451) have similar O-isotopic compositions (see diagram below). Nevertheless, HeB 002 and the Vermillion pallasites have disparate olivine compositions (HeB 002: Fa7.7 [±0]; Choteau: Fa9.2–10.1/10.3 [±0.6]) and FeO/MnO ratios (HeB 002: 24 [±1]; Choteau: 27–35/33.5 [±2.5]), which indicate they are not genetically related (MetBull and Gregory et al. (2016). Coincidentally, Hassi el Biod 002 and the Vermillion pallasites plot within the field of the acapulcoite–lodranite clan (see plot 1 and 2). However, differing mineral chemistry casts doubt on any genetic relationship between these ungrouped pallasites and the acapulcoite–lodranite clan.

Oxygen Isotope Composition of Ungrouped Pallasites
standby for oxygen isotope diagram
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Diagram adapted from Gregory et al., 47th LPSC, #2393 (2016)

Based on all of the data gathered so far, it could be concluded that the pallasites in our collections represent at least nine separate parent bodies: (1) main-group high-Δ17O; (2) main-group low-Δ17O; (3) Eagle Station group; (4) Milton; (5) Choteau + Vermillion + Y-8451; (6) Zinder + NWA 1911; (7) NWA 10019; (8) LoV 263; (9) Hassi el Biod 002. In addition, several pallasites with anomalous silicates (e.g., Springwater) and anomalous metal (e.g., Glorieta Mountain) could possibly increase the number of unique parent bodies. Proposed scenarios for pallasite formation, including ferrovolcanism, can be found on the Imilac page. The specimen of Hassi el Biod 002 shown above is an 18.3 g partial slice, photography courtesy of Mark Lyon.

Hassi el Biod 002 Slice and Individual
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Photos courtesy of Dr. Carl Agee—UNM