Sample No.: ALHA77262

Location: Allan Hills

Field No.: Y78010309

Weight (gms): 861.5

Meteorite Type: H4 Chondrite

Physical Description:

The specimen is covered by dull brownish-black, polygonally fractured fusion crust on all-surfaces with the exception of the B surface, which is only partially covered. The angular stone is approximately 9.5x7.5x6.5 cm. Snow/ ice was present on the sample when it was removed from cold storage. Areas of the sample are covered with a thin white coating, presumably evaporites. After drying the sample in the nitrogen cabinet, additional white material was noted around many of the surface cracks that was not present during initial processing. Small irregular and round inclusions are apparent on the sawed surface. Metallic particles present in the light gray matrix material of the sawed surface have oxidation halos. A weathering rind, as much as 0.8 cm thick, is present on the stone.

Petrographic Description: Brian Mason

The section shows well-developed chondritic structure, the chondrules ranging from 0.2-1.4 mm in diameter; a variety of types is present, the commonest being porphyritic to granular olivine, fine-grained pyroxene, and granular olivine-pyroxene. Some of the chondrules are fragmented. The chondrules are set in a fine-grained granular matrix consisting largely of olivine and pyroxene, with minor amounts of nickel-iron and troilite (nickel-iron in greater amount than troilite). Some of the pyroxene is polysynthetically twinned clinobronzite. The meteorite is extensively weathered, with limonite pervading the section and also concentrated in veinlets. -Microprobe analyses show somewhat variable composition in olivine (Fa15-19, average Fa16) and pyroxene (Fs13-16, average Fs14). The meteorite is classified as an H4 chondrite.