In California, where mining has been the leading, and sometimes, almost the only industry, the tourist naturally desires a clear and concise statement of the means employed in obtaining the precious metal. The following table may aid him:
GOLD MINES IN CALIFORNIA ARE:Placer mines are also classed according to topographical position, and the methods employed in working them.
The gold was probably all originally encased in veins, which varied in width and extent in different localities. The breaking and grinding of the glacial epoch, and the disintegration of more recent ages, has partially or wholly freed the gold from its rocky bonds. The eroding streams have dislodged the particles of gold from the place where they were previously deposited, and have carried them with the current until some rock, sand-bar, or hollow basin, has offered them a resting place. Here we find the principles of the two kinds of mining which have been employed in California. The glacier was the prototype of the quartz mill; while aqueous erosion is but Natures system of hydraulic, or placer mining.
The present streams still continue their work of depositing the foreign matter which, either by natural causes, or the labor of man, enters their waters. The nature of the substances which the current carries down stream regulates, in a great measure, the manner and location of deposit. If large boulders are transported, they are pushed by the current along the bed of the stream until they reach a point where they successfully resist the diminished force of the water, or become lodged against some impediment in the stream-bed. If logs, or tree trunks, are carried away, they float on the surface until the stream widens and becomes so shallow that they are imbedded in the bottom, or on the banks. When boulders, or tree-trunks, lodge at the bottom of a stream, they form nuclei for collections of pebbles, sand, or mud, and begin the formation of sand-banks and bars. When logs lodge in such a manner that they permit stony and earthy matter to pass by them, and only intercept objects floating on the surface, they produce the snags which interfere with inland navigation, and form the jams on logging streams. Thus river-bars are formed around a nucleuseither organic, or inorganic. The coarser gravel only is first detained, and as the structure progresses, sand and mud are added. Along the upper end of these bars floating particles of gold find a lodgment. Thus originate the river-bed claims, to mine which the streams are turned from their courses; bar-claims, where the gold is mined at low water; bench-claims, where the bars are on narrow table-lands, once the beds of rivers; and flat-claims, where the wash of rivers has been spread over a level space of country. Some hill-claims, or mines in which the gold-bearing dirt lies under an accumulation of nonauriferous soil, have evidently been formed as bars, and, in the changes of time, have been covered to a great depth by the wash of other streams. Gulch-claims are formed, as are those of river beds, with the exception that a small quantity of water has been the agent.
According as the pay-dirt is near the surface, or remote from it, placer mines are shallow, or deep.
The manner of working these various claims demands notice. The beds of streams along which auriferous-earth is carried are more or less rich in gold. Owing to the swiftness of the mountain streams the only way of reaching these river-bed claims is to turn the water into some other channel. In working on river-bars it is not usually necessary to turn the course of the river, as work is deferred until late in the season, when the streams are low. Deep claims are reached by shafts, or, more generally, by tunnels, through which the auriferous soil is transported, and it is afterward washed at some convenient locality. Ancient river-beds are also reached by tunnels, the gold being treated in the same manner as that obtained in the hill-claims.
In the early days of mining in California river-bed and bar-claims were called "wet-diggings, in contradistinction to the gulch and flat-claims, denominated dry-diggings, where water was obtainable during but a part of the year, if at all. When the "deep placers began to be worked, and the extensive and complex system of ditches and flumes, which now traverse the Sierra foot-hills, was first planned, the names wet and dry-diggings were discarded, and others more appropriate substituted. In the early days of mining in this State, when gulch, or flat-claims, were found very rich, and no water was obtainable to dissolve the soil, a mode of working, since discarded, was employed, and called dry-washing. The richest dirt was placed on a raw-hide that was laid on the ground. The miner then pulverized the earth, throwing out all the pebbles with which gold-bearing soil is filled. This done, the fine dust was put into his pan, and by repeatedly throwing the dirt into the air and catching it in its descent, the earth was all blown away, and the metal remained.
The tunnels which are run into hills are usually seven feet high, and about five wide. The drift is generally run on a level, or with a sufficient ascent to facilitate the draining of the claims and the excavation of earth. Occasionally a tunnel is run down so as to avoid some rock ledge above, but unless there is a draining tunnel beneath, much difficulty is experienced from the water which may be in the hills. Tunnels generally require timbering to prevent the earth from caving, and it is frequently necessary that heavy planking be placed against the side walls also. Thus it will be seen that a tunnel is an expensive structure in some places, especially where timber is scarce. Shafts are usually dug for the purposes of prospecting. But in some localities, where the pay-dirt cannot be more easily reached with a tunnel, the auriferous soil is hoisted through a shaft.
Before describing the modes of mining at present generally adopted, it will not be amiss to state the methods of obtaining the gold in the Fall of 49 and the Spring of 50. It was not until about 1852 that what has become known as hydraulic mining was begun. The crushing of the rock to free the metal was a feature of Californian mining of still later introduction. Those who first came to the State were usually supplied with three toolsa pick, a shovel or spade, and a pan.
The pan is usually made of sheet iron, which does not amalgamate with mercury and is stronger than tin. Its diameter is about twelve inches, while the sides are six inches high, rising from the bottom at an angle of about forty-five degrees. The pan is the simplest instrument employed in the separation of gold from the soil in which it is found. It is partly filled with dirt and held under water. A gentle shaking aids in dissolving the dirt. Thus a thin mud is formed which is carried away by the clear running water. The gold dust and pebbles settle to the bottom, where quicksilver is frequently placed, and the gold is retained by amalgamation. The pebbles are thrown out, and the metal removed. An inexperienced hand loses considerable gold, but an expert in this process can make a good living in many parts of the State at the present day, although shallow mines are not generally regarded as paying. Except for the purposes of prospecting, the pan has passed out of general use, and the rocker, a later invention, has also with it gone into disuse.
The cradle or rocker looks somewhat like a childs cradle, and is provided with two rockers. The instrument consists of a box about three and a half feet long, nearly two feet wide, and four inches deep. One end, which is open so as to allow the escape of water and earth, is lower than the other. Across this cradle-box two riffle-bars are placed. These are strips of board, about one inch square, which are fastened in the bed of the cradleone near the middle and the other at the end of the boxfor the purpose of catching and retaining the particles of gold. At the elevated end of the cradle is the hopper. This is a square box with a length equal to the width of the cradle, and it is about four inches deep. It is not securely fastened to the cradle, but may be lifted off when desirable. The bottom of the hopper or riddle-box is of sheet iron, perforated with holes, that, in diameter, do not exceed half an inch. Under the hopper an apron of either wood or leather is securely fastened to the sides and inclines toward the upper end of the cradle. The miner places dirt in the riddle-box. The cradler sitting beside the machine, with one hand rocks it gently as with the other hand he dips water from the stream or pool by which he works, and pours it upon the earth in the hopper. The soil is dissolved, and the muddy water sinks through the bottom of the riddle-box upon the apron, which, by its inclination, sends it to the upper end of the cradle-box. Hence it flows over the riffles and escapes through the open lower end. The gold, together with the heavy black sand, is retained by the riffles. The traveler will, in mining districts, see many Chinamen patiently working over the tailings or refuse left years ago by Caucasian miners.
Another instrument which is used in but a few parts of California at the present day is the pudding-box. This is made of rough boards. It is about six feet square and a foot deep. Very tough clay that cannot be worked successfully otherwise, is thrown into this box together with water. A man stirs this mass until it is thoroughly dissolved. He then removes a plug, a few inches above the bottom, and allows the thin mixture of earth and water to escape. The heavier portion with the gold remains, more water is added, and the process repeated. When sufficiently separated in this manner, the pan or rocker is called into requisition to complete the work of parting the gold from the tenacious earth.
The board-sluice was, for a time, an important auxiliary in gold mining. A trough of rough boards is constructed, not less than fifty feet long, and often several hundred or even thousand feet in length. The maximum width is one foot, and it varies from one foot to five feet in width. Riffles in the sluice serve to detain the gold which is also held by quick-silver. Through the sluice a stream of water constantly runs, the dirt is shoveled in, and as the soil dissolves and is carried away, the gold sinks to the bottom.
Hydraulic mining is now extensively used. Early in 1852 the miners in the Sierra foot-hills were generally impressed with the fact that some other mode of obtaining the precious metal must speedily be adopted. Many had made money by picking the gold from crevices with knives and spoons, but this could no longer be done. The earth near the water-courses had been mined over with pan or rocker. The sluice had been employed for ground more remote from water, but that means of mining had ceased to make a rich return. Many had discovered by shafts and tunnels that very valuable deposits were to be found in strata deeper than those which they could readily reach. In the spring of 1852, a miner, whose name is not remembered, put up a novel machine on his mining claim at Yankee Jim, in Placer County. This machine was very simple. From a small ditch on the hill-side a flume was built towards the ravine, where the mine was opened; the flume gained height above the ground as the ravine was approached, until finally a head or vertical height of forty feet was reached. At this point the water was discharged into a barrel, from the bottom of which depended a hose, about six inches in diameter, made of common cow-hide, and ending in a tin tube, about four feet long, the latter tapering down to a final opening or nozzle of one inch. [Charles Waldeyer, of Cherokee, Butte County, California, in United States Mining Industry. Raymond, N.Y., 1874, p. 390.]
Thus, like all great things, did hydraulic mining have its small beginning. The hose made of raw leather soon rotted, not only becoming very offensive, but also utterly useless. Some sailors adopted canvas, and that has since continued to be used in many places, for conducting the water; in other localities iron pipe has superseded sail cloth.
The nozzle has undergone many changes and improvements. Inventive genius was immediately called into requisition to perfect the instruments of the new method of mining, which was attracting universal attention. The nozzle received a great share of notice. Numerous nozzles are in use, but the detailed description of their various styles would occupy too much space here. The general form is that of a tapering metallic tube, which moves in a ball and socket joint in the metallic end of the pipe or hose which conducts the water upon the auriferous earth.
When a way was opened to the miners by which the deep placers could be profitably worked, it was but natural that many should eagerly engage in the enterprise. But there were many items of heavy expense that appeared to only a few of the more far-sighted speculators. These were not slow to avail themselves of all the advantages which the new system placed at their disposal. Large Ditch Companies were organized, surveys were made, water rights located, and mammoth ditches, and extensive flumes constructed. Miniature rivers brought in artificial channels, down the mountain sides from the regions of never-failing snow, were led to every mining camp. When a system of ditches was first instituted in 1852, investments in it brought large returns. Water was scarce in the mining sections, from the fact that the stratification of the slate-rock had made springs impossible here. A bountiful supply now enabled the miners to work their claims more extensively. But when one large ditch scheme was superseded by a grander, the supply began to exceed the demand. Immense expense had been incurred in the construction of uncalled-for ditches. Labor was high, and extravagant wages were paid by rival companies desiring to first reach a common destination. Costly flumes were built, which, owing to subsidence and decay, as well as to their frequent destruction by snow-storms, cost large amounts for repairs. Bad engineering also caused much unnecessary expense. The companies who had engaged in the construction of these works became bankrupt, with liabilities of several millions of dollars. It is estimated by competent men that not less than $20,000,000 have been invested in the mining ditches of California, and that their present (1868) cash value is not more than $2,000,000. [Resources of the Pacific States and Territories, J. Ross Browne. S.F., 1869, p. 180.]
In many localities the high water-rates prevented the miners from working their claims, and in others when the miner had become indebted to the Ditch Companies for water, beyond his capacity to pay, he transferred his claim to cancel the obligation. Thus Ditch Companies became owners and workers of mining territory. In some parts of the State one Ditch Company has absorbed one after another of its less prosperous rivals until it has become a gigantic monopoly. We may, as an example, mention the California Water Company of El Dorado County. This company has obtained possession of very extensive water privileges as well as other valuable property.
We have thus far mentioned two of the important requisites of hydraulic mining; gold-bearing earth, and an abundant supply of water. The third indispensable necessary is facilities for the outlet and deposition of the great amount of tailings, or debris. As a ton of earth returns but a very small amount of gold, when we consider the large quantities of precious metal which has been obtained by washing earth, it will be evident to the most casual observer that the tailings which have been washed from the hill-sides down into the valleys and rivers, have been enormous in amount. Here a question of grave import arises, which has led to long and bitter contentions between the miners and agriculturists of California.
The agriculturist affirms: that prior to the extensive removal of soil from the hill-sides, many rivers of the State flowed through alluvial bottoms; that these meadow-lands were extremely fertile; that the washing of tailings in the rivers has resulted in filling up their beds, until in the overflows large quantities of volcanic debris, gravel, and sand, have been deposited on productive agricultural lands; that the lands have thus become impoverished; that the loss to the State by the ruin of these farming lands, and the destruction of the improvements thereon, has reached many millions of dollars; that the transient gain from the mines has been far less than the constant returns from the lands would have been had they not been rendered valueless. He also asserts that large tracts of forest land have been destroyed, the State being thus deprived of much valuable timber; that the soil has been washed away to the bedrock in vast areas; that these tracts are useless for all purposes, and are rapidly enlarging; and that many streams, formerly navigable, have been filled up to such an extent as to stop navigation, and necessitate extensive canals and railroads; that the bays of California have been impeded by the deltas from these mountain streams, and in a comparatively brief period the greater portion of these bays will be useless for the purposes of commerce.
The miner pleads: that mining was the first great interest in the State, and that to which California owes its rapid growth; that as the miners came before the farmers, they have a prior right; that unless outlets are granted the mines cannot be worked, and the State will thus be deprived of many millions annually furnished by the hydraulic mines. He also claims that fine gold has been deposited in these alluvial bottoms until they should be considered rather as mineral than farming lands. The miner also pleads, that if an outlet for the tailings is denied him, his expensive ditches and other structures will be useless.
Careful legislation is required to adjust these counter-claims. The mining interests should not be overlooked, neither should the soil of the State be irreparably injured for the gold which is obtained by hydraulic mining. A loss of the many millions annually added to its wealth by mining cannot affect the State of California as materially as the permanent forfeiture of large forest belts, and of thousands of acres of valuable farming lands, with consequent loss to commerce.
We may well consider a few of the mechanical appliances used in hydraulic mining. Mention has already been made of the flumes, ditches, and iron pipes which conduct the water to large reservoirs, from which it is drawn in desired quantities, and conducted through iron pipe to the nozzles, through which it rushes with terrible force against the bank to be excavated.
We will now, as briefly as possible, describe the sluice-boxes which carry the water and earth away from the mine, catch the gold, and conduct the tailings out of the miners way. A sufficient fall from the head to the bottom of the sluice-box is an all-important consideration. This grade varies from three inches, in twelve feet, where an abundant and cheap supply of water is at hand, to nine inches, in the same length of sluice-box, when the supply of water is limited. These grades may be considered as extremes. From four and a half to six inches fall in twelve feet is about the normal grade.
In arranging the grade of a sluice-box many important questions are involved. One of the greatest being the establishment of under-currents. These are large, flat boxes, generally varying from thirty to fifty feet in length, and from ten to twenty feet in width, and often containing a surface of from 500 to 1,000 square feet. These boxes are provided through their whole extent with riffles, as we have seen in the rocker, which catch the gold, or amalgam. The under-current is beside and a little below the main sluice-box. An opening from fifteen to eighteen inches in width is cut in the bottom of the sluice-box. Over this a frame-work of steel bars, about one inch square, and an inch apart, allows the fine particles of sand and metal to drop into a sloping box. This box has a pitch of about one inch in a foot. Through this box the finer materials reach the broad area of riffles, while the coarser gravel and cobble-stones are carried down in the main sluice-box. The water which flows into the under-current afterward unites with that in the sluice farther down from the mine. The cobbles and small boulders are next disposed of by a grizzly, or a grate of parallel bars which permits the finer particles to pass down through the sluice, while all stones are thrown out of the sluice altogether. If a grizzly is used, a drop of a few feet is necessary, as the material which passes through the grating must drop into a series of sluice-boxes underneath, and is thus carried farther from the mining ground. Should a precipice be along the line of sluice-boxes, a grizzly may be most profitably constructed, but otherwise the accumulation of refuse thus thrown out of the sluice soon prevents farther deposits. When a grizzly is made, and a precipice is at hand, a great amount of wear on the sluice-boxes below is prevented. Then a frame of iron bars, which may be condemned iron rails, is made, extending beneath the end of the higher sluice-box and above the drop-box, into which the finer matter falls. The bars of the frame-work are placed parallel to each other, towards the cliff, and about six inches apart. The whole frame slopes at an angle of about 30 towards the cliff, over which stones of more than six inches in diameter may be rolled, while strong wooden sides prevent their escape in any other direction.
A sluice is constructed of boards resting on strong sills, laid four feet apart. These sills are usually four inches by six, and for a double sluice, about fifteen feet long. The advantage of a double sluice is that the mining can be prosecuted at the same time that one of the sluice-boxes is cleaned up. The sluice-box is from four to six feet wide, and for the latter width, about three feet deep. The sides are supported by posts, four by five inches, and strongly braced. The floor and sides of the sluice-box are made of plank one and a half inches thick.
The paving of the sluice next requires attention. This is sometimes done with hard, flat rocks, standing on their edges, and so placed as to be least effected by the flow of water. These rocky pavements are from ten to twelve inches thick. Separate compartments, formed by pieces of stout plank permanently fixed across the bed of the sluice-box, from six to eight feet apart, prevent a great displacement of the rocky pavement, should any stone give way. Above the stone pavement the sides of the sluice-box are lined to the height of about a foot with two-inch plank, to save the real sluice from the wear of the gravel. Square blocks, about ten inches deep, are also used for pavement, especially where the sluice is in a tunnel, as the work of taking out the pavement, for the purpose of obtaining the gold there retained, is, in this way, greatly facilitated. These blocks are made of wood and fastened together in sections, with a space of an inch and a half, extending across the sluice, between the rows of blocks.
In hydraulic mines the work is done by the united forces of water and powder. The latter is employed only to shake the bank, so that water will more easily effect its removal. The hydraulic nozzle is directed against the bank of earth, and a strong head of water is turned on. A stream, from five to seven inches in diameter, apparently as rigid as a bar of steel, plays against the yielding earth. A hole, which rapidly enlarges, is ploughed out of the soil, until at length a portion of the bank caves, and is washed down into the sluices. If the earth is very tenacious, a tunnel is dug into the mine, and cross-drifts, of various forms, connected with it. In these drifts large quantities of powder, from a few hundred, up to two thousand, twenty-five pound kegs, are placed; connection is made by electric fuses, the mouth of the tunnel filled up, and the blast set off. The soil thus shaken can be removed by the stream of water. To work some mines, extensive tunnels must be dug through the wall-rock to reach the rich deposits in former river-beds. From the tunnels, drifts, or chimneys, are dug into the rich deposit, and a shaft is excavated. The earth is then washed down from above into the shaft, and is carried away in a series of sluices extending through the tunnel.
We have mentioned that quicksilver is put into sluices to detain the gold. The minute particles of gold form an amalgam with the mercury. The quicksilver, therefore, must be exposed to the gold as much as possible. With this intent, at first only a small amount of washing is done through the sluices, that the spaces between the stones, or blocks, of the pavement, may become partially filled with earth. The quicksilver is then introduced. It is scattered in a light spray all along the sluice. The first charge of quicksilver is between five and six hundred pounds for five thousand feet of sluice. After that the daily charge, applied twice a day, is about one hundred pounds. Much of the quicksilver is regained when separated from the gold.
Cleaning up is done usually once or twice a month, though in some places it is performed oftener. The pavement of the sluice is gradually taken out, while a small stream of water is applied to move the sand and fine gravel. The amalgam is scraped up, and put into iron, or wooden buckets.
The quicksilver is then separated from the gold. A quicksilver bath divides the gold from any base metal which may have combined with it. The free mercury may then be obtained by straining through a filter of canvas. After this the amalgam is washed in a bath of water and sulphuric acid, when the mercury is considered pure. The gold and remaining quicksilver is now placed in a retort. The mercury is vaporized by heat, and after passing through a tube, is condensed in water. The pure gold is then removed.
A considerable percentage of the gold is lost in hydraulic mining, in great measure on account of the rapidity with which the work is prosecuted. Fine flour gold has not time to settle through the thick water, and is carried off in the tailings.
IN: California Notes,
Chapter X, by Charles B. Turrill, San Francisco, E. Bosqui & Co., 1876.
For more about the California Gold Rush see the San Francisco History Index.
For more about the California Gold Rush see the San Francisco History Index.
Charles Beebe Turrill (1854-1927), California historian and promoter, was author of Foreign Population Held Balance that Placed City on Side of Anti-Slavery, published in 1925. His 1876 book California Notes was an early publication that encouraged California tourism. This section from California Notes, about gold mining, gives the reader a handy guide to terms and procedures used by miners. Turrill also touches on the extensive environmental damage caused by hydraulic mining. The author was twenty-two when this book was published.