Long Distance Obsidian Trade In Pre-Columbian North America

I knew that there were long distance economic links in pre-Columbian America, but I was not aware that it extended to the fruits of hard rock mining.  

On the Scioto River south of Columbus, Ohio, archaeologists identified 300 pounds of Yellowstone obsidian in mounds built by the Hopewell people 2,000 years ago. It’s possible the obsidian was traded there by intermediaries, but MacDonald and some other archaeologists believe that groups of Hopewell made the 4,000-mile round trip, by foot and canoe, to bring back the precious stone.

Via John Hawks blog.