Sample No.: GRO85201

Location: Grosvenor Mountains

Weight (g): 1400.7

Dimensions (cm): 13 x 8 x 3.5

Field No.: 2010

Meteorite Type: Octahedrite, probably IIIAB

Macroscopic Description: Roy S. Clarke, Jr.

The specimen is flat and roughly the shape of a slightly curved extended hand with closed fingers and thumb. The convex surface was the anterior surface during stable oriented flight. A distinct stagnation point is present at the center of this surface from which streamers of melt flowed to a circumferential lip that separates the anterior and posterior surfaces. The anterior surface is a dark reddish brown due to the presence of terrestrial oxides with patches of black fusion crust. The posterior surface is darker and has a uniform matte appearance. The specimen has been exposed to long terrestrial weathering, but its delicate ablation-produced markings are remarkably well preserved.

Polished Section Description: Roy S. Clarke, Jr.

A slice was removed from the narrow end of the specimen giving an area of 11 cm² for examination. A regular Widmanstätten pattern with band widths from 0.8 to 1.5 mm is present. Plessite areas and centers of taenite bands have a martensitic structure. Grain boundary schreibersite and occasional large rhabdites are present. Weathering has penetrated along grain boundaries into the interior. The anterior edge has a coating of intermittent terrestrial oxide generally less than 0.1 mm thick and containing remnant fusion crust in some few areas. The posterior edge is uniformly covered with a layered, lightly weathered fusion crust 1.0 to 1.5 mm thick. Interior to both edges is an α2 structure typical of a heat-altered zone. This α2 structure blends into a much coarser martensite structure that is present throughout the kamacite in the section. The meteorite is a medium octahedrite, probably a IIIAB meteorite.