Sample No.: ALHA77249

Location: Allan Hills

Field No.: 77122925

Weight (gms): 503.6

Meteorite Type: L3 Chondrite

Physical Description:

This is not a complete specimen. The S and T surfaces have very thin, dull, patches of fusion crust. The B surface has thin, shiny black fusion crust, portions of which have weathered to reddish-brown. There are numerous inclusions, both chondrules and lithic clasts, visible through the reddish-brown oxidation rind. The largest chondrule is approximately 0.5 cm in diameter and is lighter colored than the surrounding matrix. A few inclusions that are darker than the matrix are also observed; however, they are not as numerous or as large. The sample is angular, 11.0x6.5x5.0 cm, and has many obvious fractures on the exterior surface.

Petrographic Description: Brian Mason

The thin section shows an aggregate of well-defined chondrules, 0.3-2.1 mm in diameter, set in a small amount of fine-grained groundmass. A wide variety of chondrule types is present, the commonest being barred olivine, porphyritic olivine, granular olivine-pyroxene, and fine-grained pyroxene. The olivine chondrules frequently have interstitial glass, usually turbid and partly de-vitrified, but occasionally transparent with a pale brown color. Pyroxene grains show polysynthetic twinning. Sparse nickel-iron and troilite is concentrated on the surfaces of chondrules. Limonitic staining pervades the section, and scattered grains of red-brown limonite are present. Microprobe analyses show a wide range in the composition of olivine (Fa7-Fa35, average Fa17) and pyroxene (Fs2-Fs25, average Fs11). This range of composition, together with the presence of glass and twinned clinopyroxene, indicates type 3, and the small amount of nickel-iron suggests L group; the meteorite is therefore tentatively classified as an L3 chondrite.