Sample No.: ALHA79017

Location: Allan Hills

Field No.: 1199

Weight (gms): 310.0

Meteorite Type: Polymict Eucrite

Physical Description: Roberta Score

This achondrite is mostly covered with a shiny black fusion crust that contains flow bands on all surfaces. The areas devoid of fusion crust are medium-gray in color and speckled with light and dark colored clasts which are <1 mm in diameter. Large clasts up to 0.5 cm in length were noted. The interior, which was exposed through chipping, is lighter gray in color than the exterior. Several clasts up to 1.2 cm were exposed. This meteorite looks similar to other eucrites in the 1977, 1978 and 1979 collection. Dimensions: 7.5 x 6 x 4.5

Petrographic Description: Arch Reid

The meteorite is a breccia with mostly angular but a few subrounded clasts. Pyroxene and feldspar dominate, ranging up to 2 mm and down to very fine grains in the matrix. Some of the larger pyroxene clasts, up to 2 mm, have sharp outer rims .03 mm thick of contrasting composition. A variety of clast types occur and these include: 1) pigeonite vitrophyres comprising euhedral to skeletal pigeonites (Wo4En48Fs49) up to .6mm, in a very fine grained matrix; 2) fragments of eucrite with igneous textures; 3) dark aphanitic clasts and; 4) a feldspar-rich clast with only minor pyroxene. The analysed pyroxenes are all low Ca pigeonites, Wo6En66Fs28 to Wo8En41Fs52. Some large single pyroxenes Wo6En65Fs29 have sharply defined outer rims of Wo7En40Fs53. Feldspars range from Or.1Ab7An93to Or.3Ab12An88 with more sodic grains (Or2Ab21An77) in some of the igneous clasts. The meteorite shows a limited range of mineral compositions and clast types in a preliminary examination and is classified as a polymict eucrite or a howardite.