The
placers produced 24.2 per cent of the total gold output ir 1911, 24.8
per cent in 1912, and 24.9 per cent in 1913, a slight but steady
increase. The placers producea only 0.3 per cent of the total silver
production in 1911, and 0.2 per cent in 1912 and 1913.
The mills contributed 53.8 per cent of the total gold output in 1911,
53.6
per cent in 1912, and 53 per cent in 1913, and increased the output of
silver from 15.7 per cent in 1911, to 19 per cent in 1912, and to 20.3
per cent in 1913. They are therefore producing a slightly less
proportion of the gold but a slightly greater proportion of the silver
each year. The production by amalgamation nas been less important both
of gold and of silver in the last three years, being 23.9 per cent of
the total gold and 1.5 per cent of the total silver in 1911; 22.3 per
cent of the gold and 1.2 per cent of the silver in 1912; and 21.5 per
cent of the gold and 0.6 per cent of the silver in 1913. The
cyanida-tion process has contributed constantly increasing proportions
of both gold and silver production, yielding 26.1 per cent of the gold
and 14.2 per cent of the silver in 1911 • 30.9 per cent of the gold and
17.8 per cent of the silver in 1912; and 31.2 per cent of the gold and
19.7 per
cent of the silver in 1913. The chlorination process has produced a
declining proportion of the gold yield, 3.8 per cent in 1911, 0.4 per
cent in 1912, and only 0.3 per cent in 1913. The smelters have produced
an average of nearly 22 per cent of the total gold yield during the
last three years but the smelter output of silver has declined from 84
per cent in 1911 to 80.8 per cent in 1912, and to 79.5 per cent in
1913. The bulk of the silver production is still therefore from the
smelting of crude ore, concentrates, and other material, but the
proportion declines as the relative recovery by cyanidation increases
each year. The bulk of the gold output is still from the placets and
from amalgamation, cyanidation, and smelting, in nearly equal
proportions, the small changes in importance of each method of
recovery being indicated above.
