NORTHWEST AFRICA 16734

Numerous small stones with a combined weight of 186.1 g were found in an undisclosed location in the Sahara Desert, and they were subsequently purchased in Tindouf, Algeria by F. Kuntz. A type sample was submitted to CEREGE (European Centre for Research and Teaching in Environmental Geosciences) for analysis and classification (J. Gattacceca, C. Sadaka, D. AuYang), and NWA 16734 was classified as an ungrouped pallasite.

The NWA 16734 pallasite is composed of cm-sized olivine embedded in an FeNi-metal host, each distributed in approximately equal proportions, along with minor chromite, Ca-phosphate, and troilite. Olivine contains aligned inclusions measuring ~10 µm and composed of an assemblage of metal, troilite and spinel. Other minor and accessory mineral phases commonly present in other pallasites were not observed. Northwest Africa 16734 contains the most ferroan olivine of any other pallasite measured to date, with a fayalite value of Fa29.75 [±0.32] mol%.

Based on all of the data gathered so far, it could be concluded that the pallasites in our collections represent at least fourteen separate parent bodies: (1a) main-group high-Δ17O; (1b) main-group low-Δ17O; (2) Eagle Station group; (3) Milton; (4) Vermillion + Y-8451 + Khatgal; (5) Zinder + NWA 1911; (6) Choteau; (7) NWA 10019 ± Bordj Badji Mokhtar 001; (8) LoV 263; 9) Hassi el Biod 002; (10) Lieksa; (11) Mont Tourniat 001; (12) Gyarub Zangbo; (13) NWA 16734; (14) NEA 081. 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 can be found on the Imilac page. The specimen of NWA 16734 shown above is a 1.6 g end section, while that below is a 14.24 g end section shown courtesy of Fabien Kuntz.