Northwest Africa 6165 (NWA 6165)

(Northwest Africa)

Purchased: Dec 2003

Classification: Iron meteorite (IAB-sLM)

History: A single small iron mass was purchased in Erfoud, Morocco, in December, 2003, by F. Kuntz.

Physical characteristics: The 29 g mass measuring 3.5 × 1 × 1 cm is covered by terrestrial iron oxidation products and lacks fusion crust.

Petrography: (M. D’Orazio, M. Gemelli, DST-PI) Etched sections display a fine Widmanstätten pattern of straight kamacite lamellae with a bandwidth of 0.25 ± 0.05 mm. Kamacite lamellae show Neumann bands and sub-boundaries. Schreibersite is common as large skeleton crystals (to 1.5 cm) enveloped in swathing kamacite. They are frequently brecciated and cemented by terrestrial oxidation products. The heat-affected rim (maximum observed thickness 250 µm) is locally very well preserved. Close to the heat-affected rim are found melted schreibersite crystals with dendritic texture and the kamacite is recrystallized into serrated α₂ grains.

Geochemistry: Composition of the metal (ICP-MS; D’Orazio and Folco, 2003) is: Co = 0.492, Ni = 10.8 (both in wt%), Cu = 214, Ga = 18.0, Ge = 24.2, As = 21.2, W = 0.72, Re = 0.03, Ir = 0.40, Pt = 3.45, Au = 1.60 (all in ppm).

Classification: Iron meteorite, fine octahedrite, IAB-sLM, moderate weathering grade.

Specimens: Two etched full slices (3.03 and 2.53 g) are on deposit at DST-PI. F. Kuntz holds the main mass.