Sample Petrographic Description
Sample Number | MIL 13013 |
Newsletter | 39,2 |
Location | Miller Range |
Field Number | 23788 |
Dimensions (cm) | 18.5 x 9.0 x 6.5 |
Weight (g) | 2893.90 |
Original Classification | Iron-IAB |
Weathering | |
B | |
Fracturing | |
A | |
Macroscopic Description - Tim McCoy | |
This highly irregular mass is heavily pitted, although relatively smooth areas possibly suggestive of fusion crust occupy only about 20% of the mass. Most of the fusion crust appears to have been weathered or removed, although the irregular surface was probably sculpted largely by atmospheric entry and weathering is relatively minor (a few mm). A few deeper indentations are typical of iron meteorites where less-resistant phases (e.g., schreibersite, troilite) are preferentially ablated during atmospheric entry. Minor mm-sized rust halos are present across the specimen. | |
Thin Section Description (,2) - Cari Corrigan, Tim McCoy | |
A complete longitudinal section was studied from one end of the meteorite. To the unaided eye, the meteorite is a coarse octahedrite with kamacite lamellae of 1.5-2 mm. No fusion crust or α2 region was observed. On closer inspection in the microscope, both kamacite and taenite have been transformed, likely by shock, to numerous a subgrains with interstitial γ. In the kamacite lamellae, the subgrains are typically 50-100 µm in size with α far more abundant than γ. In the taenite interstitial areas, subgrains are typically ≤25 µm with γ dominating. Graphite rosettes are present, with sizes of ~100 µm. No silicates were observed. A microprobe traverse across the section yielded an approximate average composition of 8.9 wt.% Ni and 0.38 wt.% P. Compositionally and structurally, this meteorite resembles the IIIAB Juromenha (Buchwald, 1975). The presence of graphite suggests that this meteorite may be a IAB iron, but further studies are warranted. |
Antarctic Meteorite Images for Sample MIL 13013 | ||||
Lab Photo(s) : | ||||