Sample No.: ALHA78085

Location: Allan Hills

Field No.: 435

Weight (gms): 219.3

Meteorite Type: H5 Chondrite

Physical Description:

Only the B surface of the specimen (6.5 x 4.5 x 3.5 cm.) has a very thin, black fusion crust. The remaining surfaces of the sample are fracture surfaces that are weathered and stained a dark reddish-brown. A small clast (~2 mm), that appears to be troilite is present on the T surface. During processing of the meteorite, the brecciated character of the meteorite and the interior light-dark structure was exposed. The light portion of the chondrite exists as numerous clasts in a wide range of sizes. These light colored clasts are surrounded by dark material.

Petrographic Description: Brian Mason

Chondritic structure is well developed in parts of the section, but in other parts it is less prominent, possibly as a result of local brecciation. The chondrules are set in a fine-grained granular groundmass which consists largely of olivine and pyroxene, with minor nickel-iron and troilite (nickel-iron in excess of troilite). Brown limonitic staining is present in parts of the section, along with veinlets and patches of red-brown limonite. Microprobe analyses give the following compositions: Olivine, Fa18; orthopyroxene, Fs16; plagioclase, An12. The meteorite is classified as an H5 chondrite.