Sample No.: ALHA78113

Location: Allan Hills

Field No.: 385

Weight (gms): 298.6

Meteorite Type: Aubrite

Physical Description:

This specimen is brecciated. Visible on the exterior surfaces are abundant very large enstatite grains (~2.5 x 2.0 cm) and less numerous dark clasts. Patches of very thin black fusion crust are present on only three of the six surfaces. Half of the B surface has thin yellowish-green weathering discoloration. Very small spots (<1 mm) of iron oxidation are present on 3 surfaces. Overall dimensions of this sample are 8.5 x 6.5 x 3 cm. The cut face shows many large white enstatite clasts. Few of these contain isolated rounded blebs of metal, of which some have oxidation haloes around. Surrounding these white clasts is fine grained dark gray material. In places this material appears as veins, while in other areas it is much larger in diameter.

Petrographic Description: Brian Mason

The thin section consists almost entirely of clasts of orthopyroxene up to 2 mm long in a groundmass of comminuted pyroxene. Accessory amounts of sulfides and nickel-iron are present as small grains in the groundmass. The section shows a moderate amount of brown limonitic staining, concentrated around the metal grains. Microprobe analyses show that the pyroxene is an iron-free enstatite (FeO<0.1%) with minor and variable amounts of CaO (0.2 - 0.6, average 0.5%). The meteorite is an aubrite (enstatite achondrite).