Northwest Africa 7335 (NWA 7335)

Morocco

Purchased: March 2009

Classification: Iron meteorite (ungrouped)

History: A single specimen was purchased in March 2009 by Andreas Gren from a Moroccan dealer in Rissani.

Physical characteristics: The 4908 g mass is shaped like a loaf of bread, with typical rusty desert weathering. One weathered edge shows Widmanstätten pattern.

Petrography: (P. Strickland and C. Herd, UAb) Cut and polished sections display 3 prominent lamellae directions. Two are at 60° intersection angles with a unique 70° intersection angle. The lamellae producing the Widmanstätten pattern have an average bandwidth of 0.6±0.2 mm, indicative of a medium octahedrite. Upon closer examination however, these lamellae are composed of multiple tiny spindles (<0.2 mm width) that are roughly parallel to each other. The spindles can also be seen in the plessite matrix displaying an octahedrite arrangement on a much finer scale, similar to that of a plessitic octahedrite.

Geochemistry: (C. Herd and G. Chen, UAb) Ni=109.8, Co=8.40 (both mg/g); Cr=21, Cu=229, Ga=50.8, Ge=41.2, As=8.66, W=3.67, Ir=12.3, Pt=26.3, Au=1.73 (all μg/g); Sb=210 (ng/g). Obtained by ICP-MS using North Chile as a calibration standard.

Classification: Ungrouped, plessitic octahedrite. Although Ni content is similar to IB, IIC, and IIIAB groups, Ga and Ir concentrations are outside limits for these groups. The texture shows characteristics of both medium and plessitic octahedrites.

Specimens: Two polished and etched specimens (151.1 and 7.7 g) and a 25 g analytical specimen at UAb. Remainder with Gren.