Excerpt from Mineral Resources of Michigan With Statistical Tables of Production and Value of Mineral Products for 1915 and Prior Years: With a Treatise on Limestone Resources The production of the Michigan copper mines during the year 1915 was the largest in the history of the industry. According to the figures of the U. S. Geological Survey, the total refined copper produced amounted to pounds, as compared with pounds in 1914 and with pounds in 1912, the record production previous to 1915. There was mined and milled in the Lake Superior district tons of ore-producing concentrates, containing pounds of copper, or a recovery of slightly above one per cent of copper from the ore. A portion of the concentrates produced was not smelted in 1915. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.