Northwest Africa 7795 (NWA 7795)

Northwest Africa

Purchased: 2012

Classification: Iron meteorite (IAB, ungrouped)

History: Jason Utas purchased the iron from Gary Fujihara on ebay in late January 2012.

Petrography: As described for NWA 8154, NWA 8155, and NWA 8539, the metal consists of grains 0.20 × 0.15 mm with no evidence of an octahedral pattern. The structures is anomalous. The absence of a pattern suggest fast cooling. The small graphite ellipsoids (sometimes arranged like the petals of a flower) may reflect the locations of the last, C-rich melt to crystallize.

Geochemistry: Composition: Co, 4.72 mg/g; Ni, 136.0 mg/g; Ga, 50.2 μg/g; Ge,~320 μg/g.; As, 16.0 μg/g; Ir 22.0 μg/g; Au, 1.545 μg/g. The meteorite is compositionally a member of the IAB complex.

Classification: The meteorite is classified IAB-ungr. On most element-Au diagrams it plots close to IAB-sLM but there are large deviations in some elements (a factor of 2 for W) and IAB-ungr is the best choice.

Specimens: This meteorite is closely similar to NWA 8154, NWA 8155 and NWA 8539 and appears to be paired with them.