Obsidian Cliff in Yellowstone Park is the largest deposit

of obsidian in North America. Native Americans have used this for thousands of

years for scrapers, spears and arrow heads. More than two dozen tribes would

peacefully gather obsidian in this war free zone. Pieces of this obsidian has

been found as far as the East coast and central America. Knapping, the process

of making arrow heads is still used today.

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