Northwest Africa 12767 (NWA 12767)

Mali

Find: April 2018

Classification: Iron meteorite (ungrouped)

History: A single 6.3 kg mass was found in Mali in April 2018

Physical characteristics: The main mass is an irregularly shaped rock with a dark-brown exterior and no obvious regmaglypts.

Petrography: (C. Herd and L. Tunney, UAb) Optical and SEM examination of a 3.5 × 4 cm polished and etched slice, as well as images of etched surfaces provided by the owner, show kamacite spindles up to a few mm long and approximately 100 μm wide, often in clusters. Schreibersite grains are typically enclosed by kamacite; the matrix consists of taenite exsolved on a sub-μm scale. Also visible are trains of elongate kamacite crystals up to several cm long and 1-2 mm wide. These crystals are also cored by scheibersite. No inclusions were observed on any cut surfaces, and no weathering veins are evident.

Geochemistry: (C. Herd and L. Tunney, UAb) ICP-MS data, using sample of North Chile (Filomena) as standard: Ni = 12.3, Co = 0.80 (both wt%); Ir = 5.0, Ga = 28, Ge = 139, As = 22.8, W = 1.0, Re = 0.35, Pd = 5.9, Pt = 20.9, Cu = 179, Au = 2.5 (all µg/g).

Classification: Iron, ungrouped. Although the composition suggests a relationship to the IAB-sHL subgroup, Co, Ir and Pt are all too high. The lack of silicate inclusions is also inconsistent with the IAB group.

Specimens: Type specimen of 61.9 g at UAb. Main mass with A. Habibi.