In
all, 26,445,846 short tons of ore containing gold and silver were mined
and sent to reduction works in 1908. This can not be directly compared
with the corresponding total for 1907, because that included the whole
tonnage from Michigan, or nearly 10,000,000 tons, whereas it has been
found possible in 1908 to trace the relatively small silver production
of that State to about 2,000,000 tons of copper ores. Taking these
changes into consideration the ore production of 1907 was 23,788,934,
and that of 1908, therefore, shows an increase of 2,656,912 tons.
The
division of the tonnage shows that the siliceous or dry and the copper
ores are by far of most importance with, respectively, 9,633,939 and
14,041,795 tons, against 8,080,601 and 12,198,675 tons in 1907. The
quantity of lead ores containing gold and silver was 2,392,030 tons, a
decrease of about 400,000 tons compared with the tonnage of 1907. The
tonnage of zinc ores increased somewhat, to 69,177 tons, but the
lead-zinc ores. decreased heavily, from 1,048,592 tons in 1907 to
240,934 tons in 1908.
The
tonnage of siliceous ores increased notably in all States except
Oregon, New Mexico, and South Carohna. Nevada made the most striking
gain, from 628,501 tons in 1907 to 951,880 tons in 1908. Alaska,
California, and South Dakota also made great increases.
General
gains are also shown in copper ores, especially in Utah, which gained
over 1,000,000 tons, and in Nevada, Arizona, and California. Less
copper ores than in 1907 were mined in Alaska, Colorado, Idaho, and New
Mexico. The larger tonnage was mainly due to the beginning of the
mining on a great scale of the so-called "porphyry ores" of Utah and
Nevada. Lead ores (including a small amount of copper-lead ores) were
mined mainly in Idaho, Colorado, and Utah; but while the great tonnage
in Idaho, chiefly from the Coeur d'Alene mines, increased considerably,
the output of Colorado and that of Utah was reduced to almost one-half
of that of 1907.
The tonnage of lead-zinc ores of Colorado declined heavily in 1908, and only minor amounts were shipped from other States.
The
greatest average extracted values in gold and silver are found in the
class of the siliceous ores, but they declined to $7.28 per ton in 1908
from $8.27 per ton in 1907. The figures indicate $16.58 for Nevada,
against $25 in 1907; $11.34 for Idaho, against $13.60 in 1907; $5.32
for Arizona, against $6.47 in 1907; $5.09 for California, against $5.75
in 1907; $2.28 for Alaska, against $2.30 in 1907; $3.03 for Utah,
against $3.36 in 1907. The tendency to lower average values is manifest.
The
copper ores were very much poorer in gold and silver; the highest
average values of $16.67 and $4.68 per ton are found, respectively, in
Colorado and Idaho. In the copper-producing States proper the values
per ton were verv much lower; Utah, $1.24, against $3.09 in 1907;
Montana, $1.32, against $1.43 in 1907; and Arizona $0.54, against $0.56
in 1907.
The
lead ores averaged $3.55 per ton in gold and silver, against $5.81 in
1907. In Colorado their average precious metal value was $11.58,
against $7.72 in 1907; in Utah $10.47, against $10.02 in 1907; in these
States a smaller tonnage of richer ores was mined. The lead-zinc ores,
chiefly from Colorado, average $2.01 per ton in gold and silver.
