Sample No.: ALHA77260

Location: Allan Hills

Field No.: 77123017

Weight (gms): 744.3

Meteorite Type: L3 (tentatively)

Physical Description:

The specimen is oblong 14.0x5.5x6.5 cm. A thin fusion crust, 0.5 mm, covers 50% of the specimen. There are several fractures that penetrate the stone and snow was preserved in these when it was removed from cold-storage. Light colored chondrules and lithic clasts, up to as much as 0.5 cm in maximum length, were observed on the fractured surfaces. Apparently the reddish-brown color of the weathering rind masks out the darker inclusion on the exterior surfaces. The meteorite appears to be weathered throughout.

Petrographic Description: Brian Mason

The section shows well-developed chondritic structure, chondrules ranging from 0.2-1.5 mm in diameter; some of the chondrules are irregular or broken. A variety of types is present, the commonest being barred olivine, granular olivine-pyroxene, and fine-grained radiating pyroxene. The barred and granular chondrules have interstitial glass, usually turbid and partly devitrified, but sometimes transparent and pale brown in color. Much of the pyroxene is polysynthetically-twinned clinopyroxene. The groundmass is fine-grained olivine and pyroxene, with minor subequal amounts of nickel-iron and troilite. Limonitic staining and occasional patches of limonite are present throughout the section. Microprobe analyses show highly variable composition for both olivine (Fa7-23, average Fa16) and pyroxene (Fs1-28, average Fs11). The highly variable composition of olivine and pyroxene indicates a type 3 chondrite, and the small amount of nickel-iron suggests L group, so the meteorite is tentatively classified L3; however, certain assignment should await further investigation.