Sample No.: ALHA79004

Location: Allan Hills

Field No.: 1159

Weight (gms): 34.9

Meteorite Type: H5 Chondrite with enclaves

Physical Description: Roberta Score

Most of this tabular stone has been weathered to a reddish-brown color. Patches of yellow are visible on one surface. Approximately 5% of the interior is gray in color while the remaining material has been weathered to a deep reddish-brown color. Dimensions: 5 x 3 x 1.5 cm.

Petrographic Description: Brian Mason

The section shows well-developed chondritic structure, with chondrules ranging from 0.2-1.2 mm in diameter; a variety of types is present, the commonest being granular and porphyritic olivine and fine-grained pyroxene. The matrix is fine to medium-grained, and consists largely of olivine and pyroxene, with minor amounts of nickel-iron and troilite. An enclave of granular polysynthetically twinned clinopyroxene, 2.4 mm across, is present on one edge of the section. The specimen is somewhat weathered, with brown limonitic staining throughout the section. Microprobe analyses show olivine (Fa16) and pyroxene (Fs14) of essentially uniform composition in the chondrules and groundmass; the composition of the pyroxene in the enclave is variable, as follows: Wo0.6-3.7, En 60-85, Fs11-38. The meteorite is classified as an H5 chondrite, although the enclave properly belongs to a lower type.