128
MINERAL RESOURCES.
form
by the smelters and refineries. The miners furnish the United States
Geological Survey with confidential reports on assay values and
tonnages of ore and concentrates shipped as the measure of their output
and the mine figures are reported by the Survey so far as possible in
terms of recoverable metal; and the smelters and refineries report the
metals eventually produced, first as unrefined and finally as refined.
In
using the mines report it should be noted that tonnages and metal
output given are based not on ore mined but on ore treated or sold
during the year. Of course most of the ore treated or sold is also
mined during the same year, but some of it is necessarily mined during
the preceding year. It must not be overlooked also that the mines
report aims to give the recoverable content, not the assay content, of
ore treated or sold. A part of the actual recovery is of course made
during the early part of the following year for ores treated or sold
late in the year under review, but the basis of the report is
essentially metal recovered at whatever time from the tonnage treated
or sold during the year covered by the report. For the second and third
items enumerated the recovery figures are easily had, as the ore is
treated on the ground, and the metal content of the bullion, either
base or unrefined, is readily known. In the third item the refining
loss and in the fourth item the combined concentrating, smelting, and
refining losses must be considered. In the case of the precious metals
the concentrating losses may be large and must be allowed for, but the
smelting and refining losses are known to be very small and in ordinary
practice to be more than offset by certain gains. These gains are of
small quantities of precious metals (not paid for, but actually
recovered from ores of copper, lead, and zinc) and certain differences
in quantity of gold and silver between actual recovery and basis of
settlement—for instance, silver is usually paid for on the basis of 95
per cent of the current New York price and gold at from $19 to $20 per
fine ounce. From this it is seen that producers reporting in terms of
dollars only will frequently be giving figures corresponding to
production below actual final output of metal, and if they erroneously
report net proceeds, as they sometimes do, their figures are still
further below. Other gains offsetting refining and smelting losses are
the relatively small quantities of precious metals, principally gold,
not regularly reported from the mines, but coming from transitory
placer miners whose production escapes estimate, from stolen ore
treated in improvised "assay offices," and from smelter and refinery
cleanings and similar material. Although mine reports in the aggregate
may appear, therefore, to give figures of gold and silver that are too
high, it is known from actual practice and comparison, later discussed,
that final recoveries, especially for gold, are somewhat in excess of
those reported from the mines.
COMPARISON OF MINT REPORT AND MINES REPORT.
Of
the two plans outlined for ascertaining the gold and silver production
of the United States it may be said that the one is a measure of the
mining industry and the other a measure of the metallurgical industry;
the one reports the production and recoverable content
