LEW88516 Petrographic Description

Antarctic Meteorite Newsletter, Volume 14, Number 2
September 1991

Sample No.:	LEW88516
Location:	Lewis Cliff
Field Number:	5348
Dimensions (cm):	2 x 2 x 1.5
Weight (g):	13.2
Meteorite Type:	Shergottite

Macroscopic Description: Cecilia Satterwhite
Pitted and mostly shiny fusion crust covers 80% of LEW88516. The sample's interior consists of green/black matrix which appears glassy and has conchoidal fractures. Several dark colored inclusions are present.

Thin Section (,3) Description: Brian Mason
The section shows that this meteorite is an achondrite with the approximate composition (volume percent): olivine 50, pyroxene 35, maskelynite 8, opaques (mostly chromite, with a little troilite) 2, brown glass 5. Olivine is present as rounded anhedral to subhedral grains, up to 1.8 mm long, and weakly pleochroic in pale brown. Pyroxene occurs as colorless subhedral grains up to 3 mm long, showing undulose extinction, and maskelynite is interstitial to the olivine and pyroxene. Dark brown glass containing numerous birefringent needly-like crystals (probably olivine) occurs as veinlets and patches up to 1.5 mm across. A little fusion crust is present on one edge. Microprobe analyses gave the following compositions: olivine, Fa₃₃; pyroxene, Wo₅Fs₂₈; maskelynite, An₅₃. The meteorite is a Shergottite; it resembles ALHA 77005 in texture and mineral compositions.