As early as 10,000 years ago, the Tahltan people, who now live in Dease Lake, Telegraph Creek and the Iskut, used obsidian from Mount Edziza to make tools and weapons for trading material. This is the main source of obsidian found in northwestern British Columbia, which was traded as far away as Alaska and northern Alberta. Obsidian is a type of naturally occurring glass that is highly valued for its cutting qualities. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture, creating razor sharp edges.