In This Issue

摘要

Researchers routinely sift Antarctica's snow and ice to find mi-crometeorites-cosmic dust particles related to chondrites, the most abundant class of meteorites. Matthieu Gounelle et al. report rnthe discovery of a unique basaltic micrometeorite, MM40, in the Terre Adelie region of Antarctica. The authors suggest that the micrometeorite is not related to chondrite, and its composition indicates that it was once part of an asteroidal or planetary crust. The sample weighs a few micrograms and consists of two major phases-rnplagioclase and pyroxene-as well as quartz, typical of basaltic rocks. The presence of a thin magnetite shell at its surface certifies its extraterrestrial nature.