Nevada County CA Archives History - Books .....Cement Mining 1867
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Book Title: Bean’s History And Directory Of Nevada County, California

CEMENT MINING.

  Cement mining, properly, is a branch of placer mining, and the term is applied
to the reduction of the cemented gravel found in the ancient river channels. In
this county, the business has become of leading importance, requiring skillful
engineering in mining the gravel, and expensive machinery in reducing it and
collecting the gold. Little York township has taken the lead in this branch of
mining, where capital to a considerable amount has been invested in the
business. Cement mills have also been erected in Washington, Nevada, Grass
Valley and Bridgeport townships, but the yield from this source is small, as
compared with that from other branches of mining. In Little York, however, it is
the leading business. When the rich deposits along the margins of the streams
had been worked out, and the shallow surface diggings were impoverished, the
miners directed their attention to the deep hills and ridges in search of the
precious metal. The cost and labor required to open the claims was much greater
than in the shallow diggings, but the reward frequently more than
counterbalanced the risk and preliminary outlay. At first, extensive tunnels
were run, and, where practicable, deep shafts were sunk, and the rich gravel on
the bedrock drifted out; afterward, when the hydraulic hose cause into use, the
hills were washed down entire, sometimes to a depth of several hundred feet.
Gold in greater or less quantities was found in the earth from the surface down,
in some claims being sufficient to pay running expenses; but for their profits
the miners depended on striking rich pockets in the gravel beds at the bottom.
Numerous channels were found under the high ridges where ancient streams had
once coursed their way toward the ocean, leaving deposits of gravel containing
gold, similar to those found in the existing streams. Some of this gravel was
found to be cemented, requiring more or less force to pulverize it, in order to
save the gold by the sluicing process. For this purpose, various expedients and
appliances have been devised, among which is the erection of stamp mills,
similar to those used in crushing quartz.

  Blue gravel, rich in gold, was found in different places in Little York
township in the summer of 1852, and in the winter of the following year it was
found in the claims of Rogers & Co., cemented so compactly that it had to be
blasted and gadded out. The method adopted by this company to work the cement
was to run it through sluices, save the tailings and allow them to remain some
months until the action of the elements had partially decomposed them, then
sluice them again. In this manner each lot of tailings was run through the
sluices six or eight times, requiring, probably, two or three years in the
operation. The Chinamen work the cement in the same manner now, and some are of
the opinion that it is the most economical and effectual method of working it.

  The first stamp mill for crushing cement was erected by the Massassauga
Company, on Albany Hill, near Little York, in the summer of 1857. This company
sunk several shafts that year, one of which is now used by Curran & Buckman, the
present owners of the claim. The first mill had no screens, but the cement was
thrown into the battery and .carried off by a stream of water. The tailings from
this mill were saved for a year or two and allowed to slack, and on being run
through a sluice yielded some $4,000. In the spring of 1858 a cement mill was
erected by Begole & Johnson, on the old Rogers & Co. claims, at Little York,
which was a considerable improvement on its predecessor, and mills have since
been built at You Bet, Bed Bog, Hunt's Hill, Gougeye, Quaker Hill, and other
places in the township. The screens now used are nearly as fine as those used in
crushing quartz, and it is well determined that the finer the cement is crashed
the more gold will be saved.

  Cement mining, like every other branch of the business, has had its ups and
downs, but on the whole has exhibited a steady progress, and been increasing in
importance, since the first mill was erected in 1857. Almost every claim, at
times, has paid largely, and again the receipts would fall below the expenses.
The blue gravel channels in Little York township usually vary in width from
fifty to a hundred feet, and wherever the position of the rock or other
circumstances were such as to form riffles large deposits of gold are found, the
same as they were found at an early day of placer mining in the existing
streams. For this reason, the business must be subject to vicissitudes, while
the hope of making big strikes will always be an inducement to perseverance.

  The theory formerly in vogue, that there was but one blue cement gravel lead
is now generally discarded by miners. There is no evidence that the blue lead at
Little York is the same as that worked at You Bet, and it is quite certain that
there are two separate leads at the latter place. The claims of Neece & West,
Brown & Co., and Cozzens & Garber are nearly in a line—Brown & Co. being in the
middle, and distant from Neece & West a quarter of a mile, and a mile from
Cozzens & Garber. It has been, ascertained by actual leveling, that the channel
which Brown & Co. are working is forty feet higher than that in the claims of
Neece & West, and six feet higher than that of Cozzens & Garber. This, we think,
establishes the fact that the three companies can not be working in the same
channel.

  Another idea has obtained, that the channels containing the blue cement are
more ancient than, and belong to a different river system from, those containing
gray and light-colored gravel, and which is successfully worked in sluices. We
are not aware that there is any substantial reason for this opinion. It may not
necessarily require a long period of time for the gravel to become a compact
cement; the cementing material, as well as the blue color, was probably derived
from the bed-rock, and exists only in certain localities. The petrifactions
found in the blue cement gravel, as well as those in other ancient channels, are
the pine, manzanita, and other varieties of wood now growing in the
mountains—indicating that no great geological changes have taken place since the
ancient channels were filled up. The channels of the streams may have been
changed by avalanches, earthquakes, volcanoes, and other causes now in force,
and without any extraordinary convulsion, such as the upheaval or sinking of a
mountain range.

  The developments thus far made, by the mining operations in this county,
indicate that the ancient streams did not differ materially from those now
existing, and that their general course was nearly the same. This, at least, is
the opinion now entertained by the most intelligent and observing miners.

  In general, the old channels are at a higher altitude than the beds of the
adjoining streams. There are, however, exceptions. At Scotch Flat, six miles
above Nevada, shafts have been sunk to the depth of a hundred and fifty feet
below the present bed of Deer creek, without finding the bed-rock. At Sailor
Flat, a mile and a half above Scotch Flat, deep shafts hare also been sunk,
without reaching the bottom, and the two places are believed to be situated °on
the same channel. Some company, with -well-appointed machinery and sufficient
means, may yet take out hundreds of fortunes from this deep channel. It is
probable that the channels of the streams have been changed over and over again,
while the mountains have been slowly wearing away, and that the deeper channels
were made by the more modern river systems.

  The facts thus far brought to light are not sufficient to enable us to form
any definite conclusions as to the old river channels. At present we can merely
theorize on the subject; and in doing this we should be careful not to become so
attached to theory as to lead us to disregard facts that may hereafter be
brought to light tending to controvert our preconceived opinions. The miners are
slowly developing facts, which will in time enable scientific men to construct a
map of the old river system and write the geological history of the California
gold fields.

  Whether cement mining is to increase until it becomes a leading branch of the
business depends upon the character of the deposits yet to be opened in the
ancient channels. A vast amount of placer mining ground, and channels for great
distances, are yet to be explored, and should a considerable proportion of the
gravel therein be found cemented so compactly as to require crushing, numerous
mills will be erected for the purpose, otherwise, it will be worked by the more
economical process of sluicing.

  At the present time, there are sixteen cement mills in Little York township,
having one hundred and thirty-six stamps; two mills in Washington, with eight
stamps; one in Nevada, with fifteen stamps; one in Grass Valley, with eight
stamps; and one in Bridgeport, with ten stamps. These make an aggregate in the
county of twenty-one cement mills, with one hundred and seventy-seven stamps.
More than half of these have been running steadily during the past year, while
the others have been idle a portion of the time for want of gravel to crush and
other causes. About five hundred men are directly employed in the mills and
cement mines. We have no accurate statistics of the amount of cement gravel
worked during the year. In some cases as much as a hundred tons is run through a
ten-stamp mill in twenty-four hours, while in other eases not more than thirty
tons is worked in the same time by the same number of stamps. The great
difference is owing to the difference in the gravel worked—at times being merely
soil and loose gravel, which is ordinarily worked in sluices, while at other
times the cement is compact and as difficult to crush as the hardest quartz. In
some eases the loose gravel is run through a mill for the purpose of saving the
gold contained in the small quartz pebbles.

  Cement mills are not usually provided with the appliances for amalgamating and
saving the gold that are now connected with the quartz mills. Copper plates and
riffles are mostly used, and the immense amount of cement crushed renders it
impracticable in most cases to work it in pans. The improvement most needed is
an effectual method of separating the sulphurets. These are found in
considerable quantities vrith the cement gravel, and generally contain
sufficient gold to yield a good profit when worked by the chlorinizing process.
If machinery, not too expensive, could be devised to separate them from the mass
of pulp it would add largely to the profits of cement mining.


Additional Comments:
Extracted from:

Bean’s History and Directory of Nevada County, California

CONTAINING A COMPLETE HISTORY OF THE COUNTY, WITH
SKETCHES OF THE VARIOUS TOWNS AND MINING
CAMPS, THE NAMES AND OCCUPATION OF
RESIDENTS; ALSO, FULL STATISTICS
OF MINING AND ALL OTHER
INDUSTRIAL RESOURCES.

COMPILED BY EDWIN F. BEAN.

PRINTED AT THE DAILY GAZETTE BOOK AND JOB OFFICE,
1867.


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