Sample No.: ALHA77015

Location: Allan Hills

Field No.: 77122945

Weight (gms): 411.1

Meteorite Type: L3 Chondrite

Physical Description:

The specimen is angular, 9.0x5.5x5.0 cm. Dark charcoal-brown fusion crust with vitreous luster covers approximately 50% of the sample. The fusion crust is preserved on the S surface, and is partially preserved on the B surface. The remainder of the sample is devoid of fusion crust, however, it is nearly the same color. Many fractures are present in the sample. Both angular lithic fragments and chondrules were observed on the B surface. They range in color from light brown to dark gray. The largest of these clasts is approximately 0.5 cm in length. When the meteorite was cleaved in half, one chip showed a surface with dark matrix and non-weathered metallic flakes, but the remainder of the meteorites' surfaces were very weathered.

Petrographic Description: Brian Mason

The section shows a close-packed aggregate of chondrules, 0.2-1.8 mm in diameter, with only a minor amount of fine-grained matrix. Chondrules are mostly olivine and olivine plus polysynthetically-twinned clinopyroxene; transparent pale brown glass is interstitial to olivine and pyroxene grains in some chondrules. Minor subequal amounts of nickel-iron and troilite are present, concentrated in the matrix and at chondrule margins; the nickel-iron grains are extensively corroded and altered to limonite, and thin veins of limonite occur throughout the section Microprobe analyses show a wide range in the composition of olivine (Fa1-Fa21) and pyroxene (Fs4- Fs24); the pyroxene is a low-calcium clinopyroxene (CaO = 0.2-0.5%). This range of composition, together with the presence of glass and twin clinopyroxene, indicates type 3, and the small amount of nickel-iron suggests L group; the meteorite is therefore tentatively classed as an L3 chondrite.