40 
 
 
 
35 
30 
~25 
 
0 
V 
 
C 
0 
~20 
 
E 
 
Iii 
 
-J15 
 
> 
l0 
 
 
 
5 
 1950 1955 1960 1965 
 
Figure 2.—Value of mine production of gold, silv~r, lead, and zinc
and total value 
of these minerals (including copper) m Colorado. 
had production exceeding 100 tons were, in order of output, Ouray, San Juan,
Mineral, Eagle, and Gunnision. 
 The increase in the average price of copper from 36.17 cents per pound in
1966 to 38.23 cents was enough to offset the decline in output so that the
value of production was virtually the same as that of 1966. 
 The Cleveland-Cliffs Iron Co. joined with the Union Pacific Railroad Co.
and 
the W. S. Moore Company to develop a copper deposit at the old Sumniltville
mine property at Summitville. Shaft sinking was begun during the year. According
to the annual report of ClevelandCliffs, a 300-ton-per-day mill would be
built, and production was expected in early 1969. 
 
 Gold.—Gold production declined onethird from the 1966 output of 31,915
troy 
 THE MINERAL INDUSTRY OF COLORADO 187 
 
 
 
 
 
 
 
 
Total 
 I' / 
*\zinc 
 I ,__ 
 / '  / 
\ ~ 
 / 
 \Lead -# 
 
 
 
I I I