The discovery of a small jade tool that was dropped into the waters off an island in the Southwest Pacific about 3,300 years ago is stirring up questions about its origin. The reason for puzzlement: the small green artifact has a chemical composition that is unlike any other described jade, and it was found thousands of miles away from the nearest known geological source.

An international team of archaeologists and geologists from the American Museum of Natural History, the University of Otago (New Zealand), and the University of Papua New Guinea investigate this unusual specimen in a special issue of theEuropean Journal of Mineralogy on jadeitite, the rock that defines one type of jade.