Obsidian Cliff

Obsidian is found in volcanic areas where the magma is rich in silica and lava has cooled without forming crystals, creating a black glass that can be honed to an exceptionally thin edge. It was first quarried from Obsidian Cliff for toolmaking about 12,000 years ago and gradually spread along trade routes from western Canada to Ohio. Unlike most obsidian, which occurs as small rocks strewn amid other formations, Obsidian Cliff has an exposed vertical thickness of about 30 meters. It is the country’s most widely dispersed source of obsidian by hunter-gatherers.