Sample No. MAC88177

Location: MacAlpine Hills

Dimensions (cm): 4.2x3x1.5

Field Number: 5740

Weight (g): 35.3

Meteorite Type: Ureilite

Macroscopic Description: Roberta Score

MAC88177 is a dome-shaped stone covered with flow-marked black and gray fusion crust on the top and frothy fusion crust on the bottom. The interior of the stone is heavily oxidized and much of it is orange. The less weathered matrix is buff colored. Several thin black veins criss-cross the interior.

Thin Section (,3) Description: Brian Mason

The section shows an equigranular aggregate of anhedral to subhedral olivine and pyroxene (grains 0.3-0.6 mm across), with minor troilite and accessory amounts of nickel-iron and chromite. Shock effects include undulose extinction in the silicate grains, mosaic structure in troilite, and minor veining. Some weathering is indicated by small areas of brown limonite and limonitic staining along veins. Microprobe analyses show olivine and pyroxene of uniform composition: olivine, Fa13; pyroxene, Wo4Fs12. The meteorite is classified as a ureilite, but it lacks the carbonaceous material characteristic of ureilites, and the olivine contains less than 0.1 % Ca and Cr.