DOMESTIC SUPPLY.
The
remarkable gain in domestic supply of gold indicated by the great
excess of $530,200,000 in imports over exports for 1916, or $76,000,000
more than the world's total output of new gold for the year, was due to
the fact that this country has been a creditor nation since the last
great movements of its gold abroad. This movement was much less
conspicuous in 1917, though the excess of imports of gold in ore
bullion and coin amounted to more than $180,000,000, due largely to the
imports of foreign refined bullion. The continuation of large exports
of silver to the Far East, and especially to the entente nations in
Europe, was due largely to demand for exchange and for the coinage of
silver money to pay troops in the field. The quantity of refined
domestic silver bullion exported was more than double the silver
contained in imported foreign ore and base bullion.
The
domestic supply of new gold comes chiefly from dry or siliceous gold
ores, treated in gold mills by amalgamation or cyanidation, or both,
and from placer gravels largely by dredging. As shown on page 645 these
ores and placer gravels supplied 25.8 per cent of the yield of gold in
1917. Examples of gold-milling ores are those of the Homestake mines of
South Dakota, the Goldfield mines in Nevada, the Grass Valley and
Mother Lode mines of California, the Alaska mines of the Juneau
district, and the Cripple Creek and upper San Miguel County mines in
Colorado. The great gold-dredging fields of California, especially of
the Marysville district, are examples of the placer gravels worked on a
large scale. A considerable output of gold is also now recovered from
the refining of copper bullion from copper ores, especially of the West
Mountam or Bingham district, Utah, the Robinson or Ely district, Nev.,
and the Summit Valley or Butte
