Sample No.: ALHA81014

Location: Allan Hills

Field no.: 1214

Weight (gms): 188.2

Meteorite Type: Fine Octahedrite

Physical Description: Roy S. Clarke, Jr.

This specimen is an irregularly shaped individual somewhat resembling a fish. It is covered with a uniformly pitted, dark reddish brown, iridescent, secondary iron oxide coating. Dimensions: 6.5 x 3 x 2 cm.

Tentative Classification: Roy S. Clarke, Jr.

A microetched surface area of approximately 4.5 cm³ was examined. The section was taken perpendicular to the long axis of the specimen near the more massive end. The edge of the section contains an intermittent thin border of oxide. Below this is a heat-altered zone up to 1 mm thick that is present, with the exception of a few small gaps, around the complete section. Remnant fusion crust was not observed. Kamacite has a rather uniform matte surface at low magnification that can be resolved with higher magnification to a fine epsilon-decomposition structure. A system of wider than average kamacite lamellae, containing frequent centered schreibersites in the 100 x 200 micron size range, is a prominent feature. Kamacite lamellae free of centered schreibersites have widths in the 0.3 mm range. Plessite fields occupy approximately two-thirds of the surface. Interiors of larger fields contain cellular plessite framed in martensite with taenite borders. Narrow plessite fields have only martensitic areas with taenite borders. Schreibersite is also occasionally present at taenite borders, and as grain boundary schreibersite bridging between adjoining plessite areas. Occasional 5 to 10 micron schreibersites are present within plessite fields. Other inclusions were not observed. The specimen is a fine octahedrite with structural similarities to the high phosphorus IVA meteorite Chinautla. It appears, however, to be even richer in phosphorus and to be distinct from ALHA78252. Chemical data will be required for definitive classification.