Sample No.: ALHA77167

Location: Allan Hills

Field No.: 77123029

Weight (gms): 611.2

Meteorite Type: L3 Chondrite

Physical Description:

This is an angular specimen approximately 12.5x8.0x6.0 cm, and is weathered very dark reddish brown. It appears that the S surface has small remnants of fusion crust, while the other surfaces are broken surfaces. Fractures are present on the N, S and B surfaces. Snow was present in a prominent fracture when the sample was removed from cold storage. Some light colored angular clasts and chondrules, up to as much as 0.5 cm, are apparent through the weathering rind. Many small holes are randomly distributed over the exterior of the stone, presumably due to the weathering out of lithic clasts and chondrules. When the sample was cleaved it broke into many pieces, none of which exposed fresh, non-weathered material.

Petrographic Description: Brian Mason

The thin section shows a close-packed-aggregate of chondrules and chondrule fragments, with a minimal amount of dark fine-grained matrix. The chondrules range from 0.2-1.5 mm in diameter, and show a variety of types, the commonest being granular olivine, olivine-pyroxene, and fine-grained pyroxene (sometimes radiating). The pyroxene is polysynthetically-twinned clinopyroxene. The granular chondrules contain intergranular glass usually turbid and partly devitrified, but occasionally transparent and pale violet in color. Minor amounts of nickel-iron and troilite are present, often concentrated on the surface of chondrules.. The meteorite is extensively weathered with brown limonitic staining pervading the section and numerous veins and small patches of limonite throughout. Microprobe analyses show a wide range in the composition of olivine (Fa2-Fa41) and pyroxene (Fs3-Fs17); the pyroxene is low-calcium, CaO=0.2-0.5%. 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 classed as an L3 chondrite.