Olivine in Antarctic micrometeorites - Comparison with other extraterrestrial olivine

The compositions of 5-micron or larger Mg-rich olivines from 26 Antarctic micrometeorite particles were examined and compared with those of other extraterrestrial olivine. The following differences were noted between the Antarctic meteorites and the generally recognized meteorite groups: (1) while refractory-rich (e.g., high Al2O3 or CaO) are common in C2, C3, and UOC meteorites, there are only rare, or possibly no refractory-rich olivines in Antarctic micrometeorites; (2) Mg-rich olivine compositions with FeO less than 1.9 wt pct are underrepresented in the Antarctic micrometeorites, relative to other unequilibrated meteorites; and (3) no Mn-rich, high-Mg olivines were found similar to those described in interplanetary dust, C1, C2, C3, and UOC meteorites.