Sample No.: ALHA77221

Location: Allan Hills

Field No.: 78012504

Weight (gms): 229.2

Meteorite Type: H4 Chondrite

Physical Description:

All surfaces of the meteorite, with the exception of the S surface, have remnant patches of thin, dull black fusion crust. The exterior surfaces devoid of fusion crust are stained by iron oxidation. Several clasts, approximately 1 mm in diameter, are apparent on the S surface. The specimen is fractured. Chipping revealed no unweathered material in the interior of the sample.

Petrographic Description: Brian Mason

Chondrules are numerous and well developed, and unusually large, ranging up to 3 mm in diameter; the commonest types are granular and barred olivine. One example of a chondrule within a chondrule (barred olivine) was noted. The groundmass consists of olivine and pyroxene, with a fair amount of nickel-iron in relatively large (up to 1.2 mm) grains, and a smaller amount of troilite. The groundmass is pervaded with fine-grained black material, probably carbonaceous. A little limonite is present. Microprobe analyses show olivine (Fa15) of essentially uniform composition and slightly variable pyroxene (Fs13-Fs15, average Fs14). The meteorite is classified as an H4 chondrite.