Sample No.: ALHA77002

Location: Allan Hills

Field No.: 77122927

Weight (gms): 235.2

Meteorite Type: L5 Chondrite

Physical Description:

Specimen reasonably angular with complete, brownish-black fusion crust which shows appreciable weathering. No broken surfaces to indicate crustal thickness. One large fracture. A few chipped corners show appreciable rusting. Specimen is approximately 6.5 x 4.5 cms in dimension.

Petrographic Description:

The meteorite is classified as an L5 chondrite. Chondrules are prominent and well-defined, 0.3-0.6 mm in diameter; most are porphyritic olivine, some fine-grained pyroxene. The matrix is dominantly olivine, in angular grains up to 1.0 mm in maximum dimension, with lesser amounts of orthopyroxene. Minor minerals in the matrix are nickel-iron, troilite, and chromite; plagioclase is present as very small grains difficult to recognize. The section is stained brown with limonitic materials and the metal grains are corroded evidently by terrestrial weathering, troilite is unaffected. Microprobe analyses show uniform composition in the olivine (Fa25) and orthopyroxene (Wo1.2 En77 Fs22), plagioclase composition averages Ab84An10 Or6, but appears somewhat variable.