La Follette, Robert M. (Robert Marion), 1855-1925, ed, La Follette, Robert M. (Robert Marion), 1855-1925, Handy, William M, Higgins, Charles · Chicago : Making of America · leaf 300
The copper mines in the upper peninsula of Michigan(the Lake Superior region) are unique. The ore is nativecopper with some silver, but containing hardly any otherimpurities. It is found as a cement binding together orreplacing the pebbles of a conglomerate, as a fiUing in anamygdaloidal diabase,… … WORLDS PRODUCTION OF LEAD
Science -- United States History · Inventors -- America · Working class -- United States · United States -- Economic conditions · United States -- Defenses · United States -- Social conditions
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