General statement.—The
totals in this table indicate that siliceous or dry ores, which in
general may be considered as gold ores proper, furnished about 63 per
cent of the whole production, and that placers yielded approximately 28
per cent. The base-metal ores furnished only about 8.5 per cent of the
total output, although the tonnage of these ores, as shown in a
previous table, was exceedingly heavy. The copper ores yielded most of
the gold from this source, or nearly 6 per cent of the total, while the
lead and lead-copper ores only gave 2\ per cent of the total. The gold from zinc ore was insignificant in amount.
Compared with 1905 there wTas
a heavy increase in placer gold, little change in the siliceous ores, a
moderate increase in gold from copper and lead-copper ores, and only
slight changes in the sum of the gold from lead and lead-zinc ores.
Placers.—Placer
gold was obtained in 1906 to the value of 1,328,360.70 fine ounces,
equivalent to $27,459,653, while in 1905 the quantity was only
934,709.26, valued at $19,222,155. The increase of 1906 over 1905 was
$8,237,498, and that of 1905 over 1904 was $6,557,949. Alaska was of
course most conspicuous in this great advance, but California also
added about $1,500,000 to its yield of placer gold in 1905. Several of
the other States, though of less importance, showed an increase in
1906, notably Montana, Oregon, Nevada, and Idaho.
Dredging continues as the source of the-increase
in California. The yields from this branch of mining in that State in
recent years have been as follows: 1904, $2,187,038; 1905, $3,276,143;
1906, $5,098,359, and a still further increase is not unlikely. The
total yield of the dredges in all States was about $6,150,000, divided
between California, Montana, Alaska, Oregon, Colorado, and Idaho.
Thirty-eight dredge
