Sample No.: EET92029

Location: Elephant Moraine

Dimensions (cm): 18.5 x 9.0 x 6.0

Weight (g): 2434.2

Meteorite Type: Medium octahedrite, IIIAB?

Macroscopic Description: Roy S. Clarke. Jr,

The specimen has a shape suggestive of a giant arrowhead, with cm-sized regmaglypts. Its dark brown color is due to a coating of terrestrial iron oxides. Small patches of fusion crust remain in surface depressions, and delicate streamers of late-stage, ablation-formed layered melt-crust are preserved at edges of adjoining surfaces. Occasional cm-long, narrow incisions several mm deep are present, possibly formed by ablation melting of schreibersite inclusions. A 52 g slice was removed 6.5 cm from the 'point of the specimen and perpendicular to the long axis. Butts of 357 g and 1954 g resulted. Suggestions of a Widmanstätten pattern (WP) were apparent on the cut surface.

Polished Section Description: Roy S. Clarke. Jr.. The 52 g slice was polished to a metallographic surface and a distinct WP appeared without etching. Microscopic examination revealed that the pattern was outlined by holes in the section, possibly due to the absence of schreibersite. A piece weighing 7 g was removed from the slice, and it was split parallel to its large surface area with an Isomet diamond saw to avoid plucking. Both pieces were polished and etched, and they produced a similar result to the earlier section. At this writing the cause of the voids is still an open question.

Exterior edges have a heat altered zone approximately 1.5 mm deep. About 20% of the length of these edges is covered with remnant layered melt crust under a thin terrestrial oxide coating. One melt crust area was 0.3 mm thick and 2.5 mm long. The kamacite band width is ~0.9 mm, and schreibersites frequently occupy centers of bands. These schreibersites are typically 0.1-0.5 mm wide, and range from small squares to elongated inclusions over a mm. Kamacite lamellae also contain occasional rhabdites in the 20-50 µm range, and a smaller generation of more numerous rhabdites in the pm and sub-pun range. Taenite lamellae appear to have been absorbed and are now represented by rows of associated small schreibersites, schreibersite-globular taenite associations, globular taenite, and larger voids where elongated schreibersites may have resided. Net plessite areas are comprised of this same general association. This specimen may be a IIIAB meteorite with an unusual ratio of bulk Ni to bulk P.