AMOUNT OF WORKABLE GRAVEL REMAINING IN CALIFORNIA.
The quantity
of auriferous gravel remaining on the flanks of the Sierra Nevada is
very great, but necessarily the amount available for hydraulic mining
is limited.
Minimum Pay Yield.—The
minimum yield per cubic yard of material which can be mined
profitably, must be considered in determining the extent of workable
deposits. This cannot be stated in advance without a knowledge, in any
given case, of the other factors : as area of ground, character and
depth of deposit, facilities for working and dump, supply and cost of
water, price of labor and amount of capital invested. In certain
localities, even under very disadvantageous circumstances, it has paid
to work gravel yielding only four cents per cubic yard; and Mr.
Skidmore states that, within his personal knowledge, a claim near Iowa
Hill, Placer County, in 1879 paid "a fair profit" when the product was
only three cents per cubic yard.
With an abundance of cheap water, four per cent.
grades, good dump, banks of light gravel one hundred
and fifty feet in height and over, a large area of ground,
labor at one dollar per diem, and good management, the
total running expenses ought not to exceed three cents per
cubic yard at the present time, and with present methods.
Therefore under these conditions gravel yielding more
than three cents per yard ought to pay a greater or less
rate of interest on the capital invested in the purchase of
the claim and water rights, the building of necessary
ditches, flumes, pipes, etc., and in the other appliances
requisite for commencing active operations.
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