Northwest Africa 11530 (NWA 11530)

(Northwest Africa)

Purchased: June 2016

Classification: Iron meteorite (ungrouped)

History: Purchased by the owner at Sainte Marie-aux-Mines in June 2016.

Physical characteristics: The main mass has an irregular shape with one flat, pitted side; the other side is more rounded. The surface is dark brown and the rounded side shows a bright patina.

Petrography: Polished and etched surfaces show no Widmanstatten pattern, with troilite nodules up to 2 mm. SEM examination reveals kamacite laths ~30 × 200 μm containing ~20 μm schreibersite inclusions. Taenite is present interstitial to kamacite laths.

Geochemistry: ICP-MS data, using sample of North Chile (Filomena) as standard (C. Herd and G. Chen UAb): Ni = 15.8, Co = 0.46 (both wt%); Ir = 23.6, Ga = 52, As = 16, W = 1.1, Re = 1.5, Os = 18.9, Cu = 535, Pd = 4.0, Pt = 13.3, Au = 2.0 (all μg/g).

Classification: (C. Herd, UAb): Iron, ungrouped. Ga, Pt, Cu, and Au concentrations too high for the high-Ni groups. Texture suggests recrystallization as a result of shock heating.

Specimens: Type specimen consisting of a 16.6 g representative slice at UAb. Main mass with Kuntz.