DENVER & RIO GRANDE WESTERN ROUTE. 



257 



help tear down the mountain. Locomotives with long lines of ore 

 cars shuttle back and forth across the face of the mountain, at times 

 directly above the spectator, then again far below. It seems to be 

 pandemonium let loose, but out of it comes the ore in a steady stream 

 that makes the spectator wonder. 



metallic copi^er. This ore orrurs as 

 grains of copper sulphide (iisseniinated 

 in a large mass of monzonite. 



From 1903 to 1909 the Boston Con- 

 solidated Mining Co., which operated 

 on part of this ground, used steam 

 shovels and produced over 43,000,000 

 pounds of copper. The ore averaged 

 1.65 per cent copper, or only 33 pounds 

 of copper in 2,000 pounds of ore. The 

 loss in milling reduced this figure to 23 

 pounds actually recovered. 



In 1904 tlie Utah Copper Co. built 

 the Copperton mill for experimental 

 work in the lower canyon. As the 

 work progressed the mill was in- 

 creased in size until it could treat 900 

 tons of ore a day. At the same time 

 underground development was proceed- 

 ing, and in 1906 it amounted to nearly 

 18 miles. The plan was to extract oi'e 

 by the caving system, but when some 

 idea was gained of the extent of the 

 ore body and the amount that would 

 be required to make a sufficient ton- 

 nage of commercial concentrate, steam 

 shovels were put to work. These 

 shovels have been used ever since, 

 partly to load ores on cars for milling 

 and partly to remove the top or cap of 

 the deposit, a brown oxidized material 

 from which part of the copper has been 

 removed by natural leaching. A photo- 

 graph taken in 1906 shows only one 

 steam shovel, and that one was at 

 work on the capping. Trees still grew 

 on the hillside, where apparently slight 

 change had been made on the surface. 



In 1909 the property of the Boston 

 Co. was consolidated \\ith that of the 

 Utah Copper Co., which thus acquired 

 740 acres of mineralized territory, 

 most of which is north and west of 

 the main canyon. When the first mill 

 at Copperton proved that the ore 

 could be successfully treated the 



Magna mill (PI. XCVI, .1), 15 miles 

 north of Bingham, was constructed, 

 section by section, until its capacity 

 was 4,000 tons of material a day. 

 The ore was concentrated at the ratio 

 of 20 tons of ore containing less than 

 2 per cent to 1 ton of concentrate con- 

 taining about 25 per cent copper, leav- 

 ing 95 per cent of the original material 

 to be discarded as tailing. The de- 

 velopment proceeded so rapidly that 

 the company was reorganized many 

 times. In 1904 it was capitalized at 

 $4,500,000, and in 1910 its capi- 

 talization reached $25,000,000. To in- 

 crease the extraction of ore the only 

 thing necessary was more steam shov- 

 els. The solitary shovel of 1906 had 

 22 companions in 1910. But trans- 

 portation and milling had to keep pace 

 with mining. The Gai-field branch of 

 the Denver & Rio Grande Railroad 

 hauled an immense tonnage, but in 

 1911 the Utah Copper Co. constructed 

 a railroad from Bingham to Garfield, 

 a di.stance of 20 miles, in order to meet 

 its needs. 



After the property of the Boston 

 Consolidated Co. was taken over the 

 3,000-ton mill near Garfield was re- 

 modeled and enlarged. This mill was 

 later called the Arthur plant. It 

 treated 8,000 tons of ore a day in 1910 

 and 15,000 tons in 1918; the Magna 

 mill treated 10,000 tons of ore a day 

 in 1910 and 18,000 tons in 1918. The 

 Magna plant was shut down in Feb- 

 ruary, 1919. In 1920 the Arthur plant 

 treated 5,500,000 tons of ore. A mill 

 treating 500 tons is considered a fair- 

 sized plant, but these mills require 12 

 trains a day hauling 40 cars of 50 

 tons of ore each. The ]Magna plant 

 alone covers 20 acres, and the com- 

 pany owns an immense acreage for the 

 disposal of the tailings. Like most 



