Excerpt from Pre-Columbian Copper Mining in North America The yield of mounds, graves and fields, as shown in the col lections, confirms in a general way the ob

Excerpt from The Copper Mines of Lake Superior Copper mining on Lake Superior commenced in 1845, about twenty-eight years since. Prior to this date copper had b

Excerpt from Copper Mining in Lake Superior There is a very generally received opinion that the copper in these beds occurs in Shoots. This does not appear to b