Rechecked Meteorite Yields New Mineral

Reexamination of a 4.5 billion-year-old meteorite has revealed tiny deposits of wassonite, a new type of mineral. Named after chemist John T. Wasson, a meteorite expert at the University of California, Los Angeles, the mineral is reported to contain only titanium and sulfur. Although TiS has been synthesized in labs, it has never before been seen in nature. Keiko Nakamura-Messenger, Lindsay P. Keller, and Simon J. Clemett of NASA’s Johnson Space Center and their colleagues described the finding last month in Houston at the 42nd Lunar & Planetary Science Conference. The group used a transmission electron microscope and X-ray spectroscopy to study small pieces of the meteorite, finding a 50-nm-wide sliver of wassonite and identifying several other mysterious, and as yet unknown, substances in the surrounding material. The TiS grain found in the meteorite is a single crystal with a rhombohedral structure, the NASA scientists reported. The meteorite, Yamato 691, which was discovered in Antarctica in 1969, likely originated from an asteroid orbiting between Mars and Jupiter, they explained. “Meteorites, and the minerals within them, are windows to the formation of our solar system,” Keller said in a statement. “Through these kinds of studies we can learn about the conditions that existed and the processes that were occurring then.”