Northwest Africa 8441 (NWA 8441)

(Northwest Africa)

Purchased: June 2012

Classification: Iron, IAB-sLM-an

Petrography: The type specimen is etched on two surfaces to yield a total area of about 10 cm². It is a finest octahedrite with kamacite bandwidth of 0.09±0.02 mm. It contains three small (0.3 to 1.3 mm diameter) FeS inclusions. Tiny amounts of schreibersite were tentatively identified at points where kamacite bands intersect. No silicates were recognized. Near the end of one surface is a wide wavy kamacite interpreted to be the boundary between two precursor gamma crystals. Weathering is minor but no heat-altered zone was recognized.

Geochemistry: Composition: Co, 5.18 mg/g; Ni, 119.5 mg/g; Ga, 37.9 μg/g; Ge, ~150 μg/g; As, 16.0 μg/g; Ir, 1.64 μg/g; and Au, 1.629 μg/g. The meteorite plots in or close to IAB-sLM fields on element-Au diagrams but differs in enough cases that the preferred classification is IAB-sLM-an.

Classification: The nearest compositional relatives are Edmonton (Kentucky) and Persimmon Creek but its Ir and W contents are higher and its Co content lower than in these IAB-sLM irons.