TAILINGS AND DUMP.
refuse material thrown aside in quartz, drift, hydraulic, or other
mines, after the extraction of the precious metal, is called "
tailings." The tailings from hydraulic mines are called " debris "
number of cubic yards of debris from the various gravel mines
discharged in 1880-1 into the streams and valleys of California,
between Chico Creek on the north and the Merced River on the south, has
been estimated at about 46,000,000. To this amount, according to
Professor Price, there should be added 1,000,000 cubic yards from the
tailings from the working of 1,500,000 tons of quartz by 12,546 stamps
Composition of Tailings.—The
tailings from mills consist of pulverized quartz particles. The refuse
from gravel-washing is of all forms and dimensions, and is composed of
the most diversified materials. The light particles of soil, loam, and
sand are easily carried forward by running water, while the rocks and
boulders, though readily transported through sluices, lodge and
distribute themselves, when discharged therefrom, in the creeks and
streams in accordance with their size, shape, and specific gravity, and
for their further removal the agencies of time and flood are necessary.
material and pipe-clay are more or less disintegrated and ground down
in the process of sluicing. When subjected to the action of running
water further pulverization and disintegration ensue, the actual
amount of which is unknown.
Wear in Running1 Water.—The wearing down of