Northwest Africa 6164 (NWA 6164)

(Northwest Africa)

Purchased: Dec 2007

Classification: Iron meteorite (IAB-MG)

History: A single iron mass was purchased from a Moroccan dealer in December, 2007, by M. Graul.

Physical characteristics: The 726 g mass, measuring 88× 70 × 55 mm, has an irregular shape. The portion of the surface originally sitting in the soil is partially covered with light-brown caliche, whereas the remaining portion is glossy dark-brown due to polishing by wind-driven sand. No fusion crust is preserved.

Petrography: (M. D’Orazio, DST-PI) Etched sections show a coarse Widmanstätten pattern with kamacite lamellae (bandwidth = 1.6 ± 0.2 mm) and comb-net plessite fields in approximately 9:1 volumetric ratio. The heat-affected rim (≤1.5 mm) is partially preserved. Kamacite lamellae show abundant Neumann bands and host crystals of cohenite (up to 4 mm in length) with inclusions of schreibersite and taenite.

Geochemistry: Composition of the metal (ICP-MS; D’Orazio and Folco, 2003) is Co = 0.502, Ni = 7.01 (both in wt%), Cu = 122, Ga = 74, Ge = 281, As = 14.9, W = 1.23, Re = 0.205, Ir = 1.99, Pt = 5.8, Au = 1.49 (all in ppm).

Classification: Iron meteorite (IAB, main group), coarse octahedrite.

Specimens: Two etched full slices (12.8 and 7.6 g) and one etched endcut (7.7 g) are on deposit at DST-PI. M. Graul holds the main mass.