108 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
Iii 1870 the connection of the Union Pacific and Central Pacific 
railroads by the Utah Central with Salt Lake Citj^, the inauguration of 
the branch road to Bingham, the gradual removal of the early oppo- 
sition of Mormon authorities to the entrance of their followers into 
mining operations, the results of experiments in the reduction of 
local ores, and the successful exploitation of the Emma mine and 
adjoining properties in the Wasatch Mountains, all combined to 
stimulate mining activities in Bingham. Many bodies of lead ore, 
mainly carbonate, were exploited. The first efficient development of 
the mines of the district was conducted by Messrs. Bristol & Daggett 
in the Winamuck and Spanish, and the largest body of argentiferous 
lead ore was developed in the Jordan and Galena mines. In 1874 
the bulk of lead-carbonate ore was exhausted, and in the Wina- 
muck, Neptune, Kempton, Spanish, and Utah sulphides had been 
encountered. 
Special attention was directed toward saving the gold in the super- 
ficial oxidized portions of the ore shoots in the silicified limestones. 
Various experiments in milling and cyaniding were conducted, and 
large stamp mills were erected. Despite claims that in special cases 
cyaniding was successful, the general opinion prevails that the pres- 
ence of copper necessitated the use of so inuch cyanide that no profit 
could be made, and, further, that the siliceous gold ores of Bingham 
have never been worked successfully. In the early eighties there 
were developed in the outer western slopes of the range bodies of 
carbonate ore which continued to afford an increasing output for 
about a decade. In 1801 and 1 S02 the leading productive mines were 
the old Jordan and Galena, Brooklyn, Highland, Telegraph, York, 
Petro, and Yosemito mines, [n L893 the decline in silver brought 
this period of activity to a close. 
A few years later the discovery of pay shoots of sulphide-copper ore 
at a time of strong demand for copper and a rise in the market value 
of lead inaugurated a new era in the camp. Reduction of copper 
sulphides having been successfully conducted, and the value of the 
Bingham copper ores having been demonstrated in 1890 on a shipment 
of 5,000 tons from the Highland Boy, exploitation for copper was 
vigorously begun and has continued to the date of writing. This has 
resulted in the disclosure of strong and valuable shoots of low-grade 
copper-sulphide ore. 
These bodies are now worked on both a large and a small scale. 
The largest ones are controlled by consolidations, including the Utah 
Consolidated, the United States Mining, Bingham Consolidated, and 
the Boston Consolidated companies, which (with exception of the lat- 
ter, which has not yet begun to ship from its well-proven shoot) trans- 
port their output either by aerial tramways or narrow-gage railroad 
to the Bingham terminal of the Rio Grande road, and thence by rail 
to smelters built and operated by each company at Bingham Junction. 
