Northwest Africa 2957

Morocco

Find: 1997

Pallasite (main group)

History: A complete stone was found in Morocco in 1997 and purchased by S. Hamani in 1999. The stone was cut in 2003 and the pieces were sold to various dealers and collectors.

Physical characteristics: Lightly weathered fusion crust with a dull to shiny luster covers the 362 g stone. Many olivine grains are cleanly exposed at the surface. Vague ablation-melt features are still visible on the metal surface.

Petrography: (T. Bunch and J. Wittke, NAU) Olivine grains up to 1.8 cm are randomly dispersed throughout the metal host. Schreibersite and merrillite typically occur adjacent to olivine. Olivine is only slightly zoned from core to rim. Metal structure shows large taenite centers with kamacite margins and rare plessitic cores. Small pockets of brecciated olivine, schreibersite, and troilite are commonly observed between large olivine grains.

Mineral compositions and geochemistry: Olivine (cores = Fa_11.8, rims = Fa_12.5; FeO/MnO = 41–44), taenite (Ni = 19.8 wt%), kamacite (Ni = 6.4 wt%), schreibersite (Ni = 30.5 wt%).

Classification: Pallasite (main group); minimal shock and weathering.

Type specimen: A 21 g sample is on deposit at NAU. Herrmann holds the main mass of 170 g.