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756
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MINERAL RESOURCES, 1918----PART I.
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In
1918 the Benguet Consolidated Mining Co., in the Province of Luzon,
treated 23,539 tons of ore which yielded 30,013 ounces of bullion
valued at $13.73 an ounce. Other deep mines were operated in 1918 and a
considerable quantity of gold was recovered by dredging.
NUMBER OF PRODUCING MINES.
The
following table indicates the number of mines producing gold and silver
in 1918 divided into placers and deep or lode mines. The placers are
those in which the gold and the silver in natural alloy with the gold,
and, in a few placers, found also with platinum are recovered from
gravels and sands, whether by hand washing, sluicing, hydrau-licking,
drifting (in frozen ground or'ancient buried river channels), or by
dredging. The deep mines are those producing gold and silver (from ores
as distinguished from gravels) mainly from underground workings,
including those whose ores are valuable chiefly for copper, lead, or
zinc, but which contribute precious metals as by-products. In addition
to producing mines here enumerated, many properties were being
prospected and developed (though prospecting and development were less
active than usual) without making any output in 1918, and many other
mining claims were being held by assessment work only.
The
enumeration of placer mines is less satisfactory than that of deep
mines, because some of the operations are only temporary and
individually small and because the production is frequently by
transitory miners not regularly working placer ground. The unit so far
as possible is, however, as for deep mines, not the operator, but the
mining claim or group of claims.
Number of mines producing gold and silver in 1918.a
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