Sample No.: ALH83016

Location: Allan Hills

Weight (g): 4.1

Field No.: 2142

Dimensions (cm): 3 x 2 x 0.8

Meteorite Type: C2 Chondrite

Macroscopic Description: Roberta Score

Fusion crust covers most of ALH83016. One surface is iridescent coppery-brown in color but other surfaces are dull black and polygonally fractured. The stone broke apart into centimeter-size (and smaller) pieces, leaving no original surfaces. The interior is black with abundant irregular shaped white inclusions and some chondrules.

Thin Section (,5) Description: Brian Mason

The thin section shows a few poorly defined chondrules up to 1.8 mm across, consisting of granular or barred olivine with minor polysynthetically twinned clinopyroxene. The bulk of the meteorite consists of opaque to translucent brown to black matrix. Scattered through the matrix are colorless birefringent grains, mostly olivine, up to 0.3 mm but usually less than 0.1 mm across. Trace amounts of nickel-iron and sulfides are dispersed throughout the section as minute grains. Well-preserved fusion crust rims part of the section. Microprobe analyses show that both olivine and pyroxene vary in composition. Olivine ranges from Fa0.3 to Fa30, with a mean of Fa11; it has a notable chromium content, Cr2O3 ranging from 0.1 to 0.5 weight percent. Pyroxene is generally close to clinoenstatite in composition. The meteorite is a C2 chondrite.