In
all, 31,624,943 short tons of ores containing gold and silver were
mined and sent to reduction establishments. This can not be directly
compared with the corresponding table for 1906, because that did not
contain the slightly argentiferous ores of Michigan and Missouri, which
amount to a total of 10,500,000 tons in round figures. Subtracting
this from the total, we have left about 21,100,000 tons, which indicate
a decrease compared to the corresponding figures of 1906 of 2,100,000
tons in round numbers. A decrease of about 500,000 tons in siliceous
gold ores is noted from California. The decrease in Colorado amounts
to about 250,000 tons and is due to a falling off in the mining of
lead-zinc ores and siliceous ores. The tonnage of Idaho remains about
the same. In Montana the decrease in copper ores is very great and
amounts to about 1,250,000 tons. This, of course, represents the
results of the temporary suspension of the work at Butte. The tonnage
of Nevada siliceous ores was increased by over 200,000 tons,
representing the begiiming of milling operations on a large scale at
Tonopah and Goldfield. The output of South Dakota was 1,471,156 tons, a
decrease of 300,000 tons. Besides Nevada, Utah is the only one of the
important States which has increased its tonnage heavily. In 1907 its
tonnage was 2,669,696, an increase of over 300,000 tons, largely due to
the beginning of the mining of porphyry ores on a large scale at
Bingham. A somewhat increased tonnage is probable for 1908. The Ely
plants in Nevada will add largely to the tonnage of 1908. Their
capacity is 4,000 tons per day. In tonnage the important States and
Territories now rank as follows: Michigan, Montana, Arizona, Utah,
Colorado, California, Idaho, South Dakota, and Alaska.
The
division of the tonnage shows that the copper ores and the siliceous
ores are most important with, respectively, about 10,100,000 and
8,100,000 tons (Michigan excluded). Compared with the figures of 1906,
this shows a decrease of about 400,000 tons of copper ore and of nearly
1,200,000 tons of dry or siliceous ores. The lead ores also suffered a
considerable loss in tonnage, amounting in all to nearlv 500,000 tons.
In 1907 2,354,426 tons of gold and silver-bearing lead ore were mined.
The zinc ores which contain gold and silver amounted to only 34,859
tons, against 68,296 tons in 1906. A large portionof the tonnage from
Tintic, Utah, has in the past been classified as copper-lead ore, but
this year it has been found possible to class these either as copper
ores or as lead ores.
The
greatest average extracted values in gold and silver are shown by the
siliceous ores, $8.27 per ton. They vary from $25 per ton in Nevada,
$14.49 per ton in Colorado, $13.60 in Idaho, to lower figures like
$6.47 in Arizona, $5.75 in California, $2.85 in South Dakota, $2.30 in
Alaska, and to the minimum of $1.49 per ton in South Carolina.
The
copper ores are very much poorer in gold and silver. The highest values
of $12.24 and $6.65 per ton are found in Colorado and Nevada. In the
copper-producing States proper the values per ton are much lower: Utah,
$3.09; Montana, $1.43, and Arizona 56 cents.
The
lead ores average $5.81 per ton, much of the value being in silver. The
lead ores of Montana appear to be the richest, averaging $24.40 in gold
and silver. The lead ores of Utah, chiefly from Park City, Bingham, and
Tintic districts, average somewhat over $10 per ton in gold and silver.
The lowest values are obtained from Idaho, where the average is $3.10.
64949—M B 1907, PT 1------0
