calls
for 125,342,836 pounds, while the smelters say that 112,520,000 pounds
represent the output. The bulk of the production in these two States is
sold in the form of concentrates by a number of large mining companies.
The figures given represent the assay values of these concentrates.
Assuming a 5 per cent loss in smelting, which seems very liberal, in
view of counteracting influences mentioned, under gold and silver, but
in part applicable to lead, there still remains an excess of almost
9,000,000 pounds of mine returns above smelter returns in Idaho, and of
almost 6,000,000 pounds in Utah.
The
zinc returns are still more unsatisfactory. The principal zinc-mining
States of the West are as follows, in their order of production:
Colorado, New Mexico, Montana, Utah, Nevada, and Idaho. The ores are so
complex, and they vary so widely in character and tenor, that
the Missouri Valley measurement by tons of ore is of doubtful value.
The loss of metal in concentration and smelting is very heavy. It is
aimed in the mines report to obtain the tonnage and assay value of the
product (crude ore and concentrates) shipped to the zinc works, and 25
per cent of the quantity of metal contained is then subtracted for
smelter loss. The matter is still further complicated by the great
consumption of zinc ores for the manufacturing of zinc white and
lead-zinc pigment. The figures given in the reports for the different
States, therefore, do not mean metallic zinc or spelter. They simply
represent 75 per cent of the assay value of the ores shipped. It is
probable that some better method may be devised, and it is especially
planned for the 1907 report to obtain a better check on the quantity of
ore consumed by the paint manufactories. At present the shipper of zinc
ores often does not know whether his product will be used for the
manufacture of spelter or of pigment.
In
the smelters report published elsewhere in this volume, Mr. Boutwell
has succeeded in apportioning for 1906 the metal according to source of
ore on the basis of returns made by the zinc works. From his tables it
appears that the Western States yielded almost one-fifth of the total
spelter, or, in exact figures, 78,590,000 pounds, and that the
principal part of the production was derived from the Central and
Eastern States. The mines report for the Western States, on the other
hand, indicated a total of 122,522,222 pounds, or nearly one-third more
than the smelters report. A large part of this difference was
undoubtedly due to ore used for pigments. Colorado has by far the
greatest production, and the bulk of it is derived from Leadville
mines. The mines report gives 86,965,308 pounds (three-fourths of assay
value of product shipped), whereas the apportioned spelter output of
the smelters is only 64,912,000 pounds. The New Mexico mines report
17,292,655 pounds, while the smelter statement is 1,110,000 pounds. A
very large part of the output of the Magdalena district in New Mexico,
which is the principal zinc camp in that Terri-tory, is, however, known to be used for the manufacture of pigments.
Some
buyers of zinc ore from Leadville mines, for instance, are known to
reconcentrate the products in Denver or Canyon before shipping to the
zinc works, and considerable loss is, of course, involved in that
operation. In the report for 1907 there will probably be an improvement
shown in the zinc statistics in the reports from both mines and
smelters.
The
zinc ores of the West, except in rare cases, contain gold and silver.
The cinders, after the distillation of the zinc, are naturally
