http://inspire.ec.europa.eu/codelist/CommodityCodeValue/obsidianINSPIRE Registry teamJRC-INSPIRE-SUPPORT@ec.europa.euhttp://inspire.ec.europa.eu/registry2015-08-18 18:09 PM CEST2015-08-18 18:09 PM CESTobsidianObsidian is the result of volcanic lava coming in contact with water. Often the lava pours into a lake or ocean and is cooled quickly. This process produces a glassy texture in the resulting rock. Iron and magnesium give the obsidian a dark green to black color. Obsidian has been used by ancient people as a cutting tool, for weapons, and for ceremonial purposes and is sometimes found by archaeologists in excavations. - http://www.galleries.com/Obsidian