Name: Grosvenor Mountains 06050 This is an OFFICIAL meteorite name. Abbreviation: GRO 06050 Observed fall: No Year found: 2006 Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)] Mass: 9.13 kg
Macroscopic Description: Tim McCoy and Linda Welzenbach The meteorite is a rounded, flattened mass and all surfaces are irregular. One large surface exhibit several cm-sized rounded pits suggestive of regmaglypts, a few linear fractures, <5% of a black coating that may be fusion crust and is dominated by irregular rocky surfaces suggestive of spallation of the original surface. The opposite large surface has a much higher percentage of the black, vesicular material which exhibits flow lines and is almost certainly the original fusion crust. This side exhibits numerous, intersecting linear fractures. Minor evaporites are present, primarily on one end of the meteorite.
Thin Section (,2, 4 and 5) Description: Tim McCoy, Linda Welzenbach and Cari Corrigan A longitudinal slice measuring ~14 x 6 cm was examined prior to thin section preparation. The slice exhibits numerous angular polyminerallic silicate clasts which range from a few hundred microns up to 4 cm in maximum dimension. Many of these inclusions have been fragmented with metal injected in fractures of these single inclusions but with offsets small enough that the original pieces can be easily recognized as a single clast. The clasts themselves exhibit disseminated metal and sulfide within them. Silicate-free or –poor regions can reach 1 cm and exhibit a Widmanstatten pattern consistent with a medium octahedrite, with kamacite bandwidths of ~1 mm. Many of the clasts are surrounded by swathing kamacite. Sulfide is relatively rare in hand samples, but can occur in local patches up to a few mm across and is found occasionally as veins within the silicate inclusions.
Two polished thick sections and one polished thin section were prepared from the meteorite. In one thick section, fusion crust was observed on one edge of the section, confirming that the vesicular, black material on the surface is the original fusion crust. Metal underlying this edge exhibits a2 structure to a depth of ~1 mm. The metallic host is dominated by kamacite lamellae with widths of 0.8-1 mm and L/W ratios of 2-4. Subgrains are present in most kamacite crystals, with subgrains of a few tens of microns to hundreds of microns and Neumann bands are reasonably common. Taenite ribbons are typically small and highly zoned, although a few larger ones exhibit a plessitic structure. Other phases present include troilite, chromite, daubreelite, schreibersite, graphite (occasionally with cliftonitic forms), and copper.
In thin section, the silicate clasts exhibit an equigranular structure of olivine, pyroxene and plagioclase with typical grains sizes of 100-200 mm, although grains up to 0.5 mm are present. Minor staining from terrestrial weathering is present. In hand sample, we observed a single green elongate silicate reaching 4 mm in length which is likely a chromian diopside. Silicates are homogeneous with olivine of Fa2, orthopyroxene of Fs8Wo2, diopside of Fs4Wo46, and plagioclase of An16Or3. The meteorite is almost certainly a silicate-bearing, low-Ni IAB iron similar in composition to others, e.g., Landes.
9.13 kg
