The
total average extraction value of gold and silver from copper ores
increased from $0.48 to $0.59 per ton in Arizona in 1910; from $1.78 to
$1.94 in California; from $16.32 to $27.91 in Colorado; and from $0.06
to $0.08 in Tennessee. It decreased from $0.24 to $0.21 in Nevada and
from $0.88 to $0.64 in Utah. The average extraction value
increased in lead ores from $2.06 to $2.27 per ton in Idaho, and from
$5.41 to $6.47 in Colorado. In argentiferous zinc ores and lead-zinc
ores decreases were general in 1910.
DISTRIBUTION OF GOLD PRODUCTION OF 1910.
Over
92 per cent of the total gold production of the United States is from
the combined contribution of the placers and the deep mines producing
dry or siliceous ores. The relative proportions of output from these
sources, however, show interesting changes from 1909 to 1910. In the
former year the placers supplied 27.26 per cent of the total gold
output and the dry or siliceous ores 64.87per cent; in 1910 the placers
supplied 23.76 per cent and the diy or siliceous ores 68.91 per cent.
In general this illustrates decreasing relative importance of the
placers as a whole, as is to be expected. The proportion of the output
from copper ore increased from 5.68 per cent in 1909 to 5.77 per cent
in 1910. The relative production from zinc ores also increased from
0.05 per cent to 0.07 per cent and that of lead-zinc ores from 0.19 per
cent to 0.29 per cent. The relative output from lead ores, however,
decreased from 1.59 per cent in 1909 to 1.18 per cent in 1910, and that
from copper-lead and copper-lead-zinc ores from 0.36 to 0.02 per cent.
The
following table gives the sources by classes of ore and by States and
Territories of the gold output of the United States in 1910, in fine
ounces:
