Sample No.: ALHA77232

Location: Allan Hills

Field No.: 77122905

Weight (gms) : 6494.3

Meteorite Type: H4 Chondrite

Physical Description:

The sample is rounded and only small patches of remnant fusion crust remain on the exterior surface. The sample is severely weathered, the entire specimen is uniformly stained reddish-brown, and fractured. When the sample was sawed it crumbled into many pieces. All of the surfaces exposed during processing were severely weathered. White deposits developed on some surfaces of the meteorite while they dried in the nitrogen cabinet. Dimensions: 20 x 19 x 14 cm.

Petrographic Description: Brian Mason

The section shows well-developed chondritic structure, the chondrules ranging from 0.4 to 1.2 mm in diameter. Chondrule types include porphyritic olivine, granular olivine and olivine-pyroxene, and fine-grained radiating pyroxene; in the porphyritic chondrules the olivine crystals are set in a turbid devitrified glass. Much of the pyroxene is polysynthetically twinned clinobronzite. The chondrules are in a fine-grained granular matrix consisting largely of olivine and pyroxene, with minor amount of nickel-iron (~15%) and troilite (~5%). The meteorite is considerably weathered, with limonite pervading the section and also concentrated in veinlets. Microprobe analyses show olivine (Fa17) and pyroxene (Fs15) of essentially uniform composition. The olivine and pyroxene composition and the presence of clinobronzite indicate that the meteorite can be classified as an H4 chondrite.