For some 1800 years, beginning abruptly about 3000 BC, some industrious peoples mined ore equivalent to 500,000 tons of copper from Michigan's Isle Royale and Keweenaw Peninsula. Who were these mysterious miners, and what happened to all all that copper? It certainly hasn't been found in the relics of North American Indians. And where was the ore smelted?
http://www.science-frontiers.com/sf090/sf090a01.htm
America's Mysterious Furnaces
Casting In Mold Found At Pit Furnace Site
Stone Masonry At Spruce Hill? -- Spruce Hill Furnaces Melted Copper?
Copper Casting At Cahokia? -- 1,000 B.C. In Michigan? --
http://www.iwaynet.net/~wdc/
http://www.science-frontiers.com/sf090/sf090a01.htm
America's Mysterious Furnaces
Casting In Mold Found At Pit Furnace Site
Stone Masonry At Spruce Hill? -- Spruce Hill Furnaces Melted Copper?
Copper Casting At Cahokia? -- 1,000 B.C. In Michigan? --
http://www.iwaynet.net/~wdc/