In 1902, De Lamar sold his Mercur and De Lamar, Nevada mines, for one million dollars each. To his discredit, the operation in the mill at DeLamar created such a fine particulate during the milling process that many workers were killed by inhaling the dust, the focus of medical study and accusation of DeLamar's inconsideration of his laborer's safety. In the late 1890s, De Lamar had turned his attention to copper. While at Mercur, DeLamar became interested in the Bingham Canyon copper mines and sent Jackling and others to inspect the deposit. DeLamar would eventually acquire a portion of the canyon, but sold out to his former Cripple Creek partners, MacNeill and Spencer Penrose who would reap a fortune in copper at Bingham Canyon, Utah, with Jackling as their manager. In July 1899 De Lamar also purchased the Bully Hill mines, in the Shasta copper district of California, and financed the big copper smelter which was operating near there. A railroad project was installed to connect level 3 of the mine with the smelter, and the project became informally known as the DeLamar Railroad, which became part of the Sacramento Valley and Eastern Railway. Like his earlier operations, DeLamar unloaded the California property for a quick profit. Also, in 1901 he invested in mines near Yerington, Nevada and formed the Bluestone Mining & Smelting Company, one of his smaller yet still profitable operations sold after his death. He next turned to Canada, taking over the great copper nickel lodes of Sudbury, Ontario and organized the International Nickel Company (Inco), a multinational mining corporation. In 1905 he and his International Nickel partners bought into the Nipissing Mine, located in Cobalt, Ontario, 300 miles north of Toronto. In May 1906, they hit the famed "Silver Sidewalk," a vein of nearly pure silver. DeLamar and his partners reportedly unloaded the property for $10 to $20 million. His next move was into the rich Porcupine district of Canada, where he became president of the Dome Mines Company, a long-term gold producer. As Inco, Dome and his other operations reached peak production during the high mineral market prices of World War I, he was one of the wealthiest men in America at the time of his death in 1918. Three former mining cities, which are today ghost towns, Delamar, Nevada, De Lamar, Idaho, and Delamar, California, were renamed after him; the last is now under water of Shasta Lake.