MINES REPORT.
METHOD OF COLLECTING STATISTICS.
The
first table in this report presents the final official figures of the
production of gold ana silver in the United States in 1913 as agreed
upon by the Bureau of the Mint, and the United States Geological
survey. With the comparatively unimportant exceptions of domestic gold
and silver contained in ores, mattes, etc., exported for reduction
during the year, these figures record the actual production of gold
and silver bullion from domestic ores in marketable form as metals,
either refined or unrefined.
Owing
to the difficulty of tracing this total gold and silver production
back to its origin by States, counties, and mining districts, however,
the Geological Survey attacks the problem of distribution by systematic
investigation of the mine production of ores containing gold and silver
during the calendar year, and of the output of the placer mines. In
this way the state of the mining industry is studied in detail, and
classification of output by methods of production and by kinds of ore,
as well as by mining districts, is obtained. The resulting figures form
the basis of the mines report.
As
already stated, the Bureau of the Mint takes into account, as the basis
for figures of production, statistics of gold and silver in unrefined
bullion deposited in the United States mints and assay offices, in fine
bars of both metals produced by private refineries, and in ores,
mattes, etc., exported for treatment.
The
data for the mines report of the United States Geological Survey may
be classified as follows: (1) Gold and silver from placers in nuggets,
dust, and bullion; (2) gold and silver in mill bullion (obtained by
amalgamation, cyanidation, chlorination, etc.) from mills of mine
companies treating their own ores, tailings, dumps, etc.; (3) gold and
silver in base bullion, matte, etc. (by assay value), from smelters
treating their own ores; and (4) gold and silver in crude ore,
concentrates, old tailings, slags, etc. (by assay value), shipped to
custom mills and smelters—all four of these classes of data being for
material treated at the mines or shipped from them during the calendar
year.
The
first item is the native gold (with silver in natural alloy) produced
from placer mines and sold to Government mints and assay offices, and
to refineries, banks, and traders. It is difficult to obtain accurate
figures for this item only in some parts of Alaska, or from transitory
miners elsewhere, or from miners who report only value received for
their output. The second and third items cover metal production by
mining companies whose mills and smelters treat their own ores and
whose products go to the mints and refineries and are covered by
confidential mine reports to the purvey. The fourth item, which covers
raw mine products shipped for treatment, gives rise to the main
apparent discrepancies between mine and mint-refinery reports on the
production of gold and silver ; for the same calendar year. The
discrepancies are due largely to the lapse of time between the disposal
by shipment of the ore as reported from the mines and its arrival and
metallurgical treatment at the mill or smelters, followed by the
refining of the products, an interval in
