On
the whole 1906 was a very prosperous year for the mining industry. High
prices for the metals stimulated prospecting and development work to an
unusual degree. Wages showed a tendency to advance. There was a great
scarcity of labor, and during the last months of the year the freight
congestion on the railroads became so serious as to interfere with the
operation of many smelting works and to delay shipments of ore.
The
year was comparatively free from labor troubles, which, unfortunately,
can not be said of 1907. In Arizona copper mining was especially active
at Bisbee and Globe. Smelting works were built or enlarged. In
California the advance in dredging operation was marked. Colorado
suffered perhaps to some extent from the great attention given to
Nevada and from some local causes, but nevertheless experienced a very
successful year. In Montana the Butte copper mines prospered and
recorded an extremely heavy production of low-grade ore. Crowds of
prospectors examined the ranges of Nevada, and Goldfield yielded
millions in gold from the wonderfully rich ore of the Mohawk and
Florence mines. Concentrating and cyanide mills were provided for
Tonopah and projected for Goldfield. Concentrating mills were built
for the great low-grade copper deposits at Ely. In Utah most of the new
activity centered at Bingham, where large quantities of low-grade
copper ore were mined by steam shovels at a cost said to approach 30
cents per ton. Concentration and smelting works were provided for
these ores.
CLASSIFICATION OF ORES.
The
gold and silver product is divided according to its derivation from
placers, from dry or siliceous ores, copper ores, lead ores, zinc ores,
copper-lead or copper-lead-zinc ores, and lead-zinc ores.
These
divisions of the ores from the deep mines are, of course, to a certain
degree arbitrary, and in many cases of complex ores doubt exists about
their proper classification.
In general, ores which contain 2-1/2 per cent or more of copper are considered as copper ores, while those with over 4-1/2 per
cent of lead are called lead ores. Special divisions of mixed ores,
such as copper-lead and lead-zinc have been established. The bulk of
the zinc ores contain at least 25 per cent of that metal. The
classification is based on the quality of the ore as mined.
DISTRIBUTION OF THE GOLD PRODUCT OF 1906.
The following table shows the source of gold in the United States in 1906, by kinds of ore and by States:
