Sample No.: ALH85001

Location: Allan Hills

Weight (g): 212.3

Field No.: 2255

Dimensions (cm): 7 x 6 x 3.5

Meteorite Type: Eucrite

Macroscopic Description: Roberta Score

ALH85001 appears to be an oriented stone covered by a shiny black fusion crust with thick flow lines. Areas devoid of fusion crust have weathered to a brownish-gray color. A discontinuous weathering rind, as thick as 4 mm, was exposed when the stone was chipped. The interior is made up of abundant laths of chalky-looking plagioclase in a light gray matrix. The way this stone has weathered is more typical of the Elephant Moraine eucrites than those found in the Allan Hills.

Thin Section (,4) Description: Brian Mason

The section shows angular fragments of orthopyroxene and plagioclase, up to 2.4 mm across, in a comminuted groundmass of these minerals. Some of the pyroxene has lamellae and blebs of exsolved augite. One large gabbroic clast, 6 mm across with individual grains up to 3 mm, is present. Trace amounts of nickel-iron and troilite are present in the groundmass. Micro-probe analyses show that pyroxene compositions are remarkable uniform, Wo2Fs32, with a few more calcic grains, up to Wo8 (possibly incipient augite exsolution). Plagioclase composition is also fairly uniform, An92-94. The meteorite is a monomict eucrite with unusually magnesian pyroxene, similar to that in the Binda eucrite.