A naturally occurring black volcanic glass extensively used in the production of edged tools. It fractures at the molecular level and produces some of the sharpest edges known on stone tools. One of the largest exploitation sites is on the Cycladic island of Melos but other sources are known at Lipari, Sicily, on Sardinia, in central and eastern Turkey, and in Hungary. Obsidian was exported widely around the eastern Mediterranean. In the Americas obsidian is found in Mexico. It also occurs in southeast Asia and in the Pacific, including important sources in Melanesia; obsidian from Talasea was traded from at least 17 000 bc. There are also many sources in New Zealand.