Sample No.: ALHA81189

Location: Allan Hills

Field No.: 1582

Weight (gms): 2.6

Meteorite Type: E4 Chondrite

Physical Description: Roberta Score

No fusion crust remains on this fractured reddish brown colored stone. Dimensions: 2 x 1.1 x 0.5 cm

Petrographic Description: Brian Mason

The section shows an aggregate of chondrules, chondrule fragments, and mineral grains set in an opaque matrix. The chondrules range up to 0.9 mm in diameter; most of them consist of granular pyroxene (sometimes with a little olivine), but a few are made up of nickel-iron and troilite. The matrix consists largely of nickel-iron and troilite, with a considerable amount of limonite formed by weathering of the metal. Microprobe analyses show that the pyroxene is close to MgSiO3 in composition (FeO 0.5-4.5, mean 1.9%; A1₂O₃ 0.02-2.4, mean 0.7%; CaO 0.1- 0.7, mean 0.3%; TiO₂ 0-0.13, mean 0.08%; MnO 0.07-0.22, mean 0.15%). Most of the olivine grains are close to Mg₂SiO₄ in composition (FeO 0.7-6.4%). One grain of a silica polymorph was analyzed. Since part of the pyroxene is polysynthetically twinned clinoenstatite, the meteorite is tentatively classified as an E4 chondrite; however, it shows some similarities to Kakangari, classified by Graham et al. (Mineralogical Magazine, V.41, p. 201, 1977) as a forsterite chondrite.