760 MINERAL RESOURCES, 1918----PART I,
DISTRIBUTION OF MINE PRODUCTION OF GOLD IN 1918, BY
SOURCES.
As
shown bv the following table, the great bulk of the domestic output of
gold" is Obtained from dry or siliceous ore—normally gold quartz and
gold-silver quartzose ores—and from placers, more than 87 per cent of
the total production of gold coming from these sources alone. The total
contribution of gold derived from the great copper, lead, and zinc
mines of the country is therefore relatively small, notwithstanding
their recent enormous development and production of ore. ,
It
is interesting to note, however, that the placer mines and dry or
siliceous ores yielded 1 per cent less of the total gold than they did
in 1917. The contribution of gold from dry or siliceous ores, which had
gradually declined from about 69 per cent in 1910 to about 66 per cent
in 1914 and had increased to nearly 68 per cent in 1915, decreased more
than 4 per cent in 1916, was 62 per cent in 1917, and 63.7 per cent in
1918. The yield of gold from copper ores, which had increased from 6
per cent in 1914 to 7 per cent in 1915 and to 9 per cent in 1916,
decreased to less than 9 per cent in 1917 and increased to 9.6 per cent
in 1918.
