Sample No.: ALHA78134

Location: Allan Hills

Field No.: 403

Weight (gms): 458.3

Meteorite Type: H4 Chondrite

Physical Description:

Snow and ice remained on the sample (7.0 x 5.0 x 7.5 cm.) when it was removed from cold storage. Dull black fusion crust covers nearly 40% of the sample. The remaining surfaces are weathered and stained by iron oxidation. On the S surface the inclusions in the meteorite have a higher relief than the surrounding matrix, probably as a result of preferential weathering. Inclusions (chondrules and lithic fragments) are visible on the other fracture surfaces but have not experienced any preferential weathering. In several areas the weathered material appears granular. Several large fractures penetrate the sample. When the sample was divided during processing, 60% of the interior was stained reddish-brown. The remaining 40% is light gray and contains many clasts, (1 mm or less). Oxidation halos are also present in this material.

Petrographic Description: Brian Mason

Chondrules are numerous and well developed, ranging from 0.3-1.2 mm across; a variety of types is present, the commonest being granular olivine and olivine-pyroxene, and radiating fibrous pyroxene. The chondrules are set in a fine-grained aggregate of olivine and pyroxene, with minor nickel-iron and troilite (nickel-iron in greater amounts than troilite). Some of the pyroxene is polysynthetically twinned clinobronzite. The meteorite is extensively weathered, with veinlets and patches of red-brown limonite throughout the section. Microprobe analyses show olivine of essentially uniform composition (Fa18) and somewhat variable pyroxene (Fs 15-Fs20, mean Fs17). The meteorite is classified as an H4 chondrite.