Tranquillityite

Australian scientists have discovered a rare mineral previously known only to be found in lunar rock samples and used it to date an Earth rock which formed over a billion years ago. Named tranquillityite after the Sea of Tranquillity, where astronauts landed on the Moon in 1969, researchers discovered the substance in rocks collected from six sites in Western Australia. Tranquillityite was first discovered in rocks brought back from the moon soon after the first Apollo mission, along with two other substances - armalcolite and pyroxferroite. Both substances were found in Earth rocks within a decade or so of the 1969 Apollo mission but the third, tranquillityite, wasn't found on Earth until now.