Meteorites from the Moon's Lava Plains
Eberhart, Jonathan, Science News
Meteorites from the moon's lava plains
Scientists have collected thousands of meteorites in Antarctica, where low temperatures keep the rocks from eroding away, a geological oddity concentrates some of them in certain places, and the often snowy and icy terrain makes them easy to spot. Researchers have identified about 10 of these meteorites as coming from the moon. All of the lunar meteorites found heretofore appear to have originated in the heavily cratered highlands that seem to constitute most of the moon's crust. But researchers now report finding three that may have arrived from the lunar lava plains, or maria.
One of these, weighing about 30.7 grams (a little more than an ounce), was gathered in an Antarctic region called the Elephant Moraine, say Jeremy S. Delaney of Rutgers University in New Brunswick, N.J., and Paul H. Warren of the University of California, Los Angeles. Designated MAC88105, this meteorite is a breccia -- a rock composed of numerous basaltic fragments and smaller grains held in a glassy matrix. Its basalt is a type with very low levels of titanium. Although remotely measured spectra have led some researchers to believe titanium is common on the moon, it is rare in basaltic moonrocks returned to Earth by space missions. …