localities in the interior of the State. Asphaltum also, a product of the southern counties, is used extensively for paving and roofing purposes. Many other mineral substances occurring in California will become of value for various manufacturing and commercial purposes in the future, some of them even now being turned to profitable account. Though silver has been included in the list of its metallic products, California can by no means be called a silver producing State-the greater part of that shipped from San Francisco being furnished by the mines of the State of Nevada. True, silver mines are not uncommon in the southeastern part of the State, and some of them contain very rich ores. This is especially the case in Alpine, Mono and Inyo counties, lying east of the Sierras. Many attempts have been made to mine and work these ores; but the veins are usually small, and mining operations in these localities, under present conditions, can only be conducted at a heavy expense. Besides, these ores, though often rich, are generally among the more complex kinds, requiring peculiar treatment. Practical operations having, however, been mostly attempted by men possessing little or no acquaintance with metallurgy, have generally resulted in failure. Under more skillful management these mines could probably be worked with large and steady profits. The copper ores found in that part of the State bordering on Arizona are usually argentiferous, sometimes very highly so; and from these and other sources, California will ultimately, no doubt, become a large producer of silver. But at present most of the silver actually obtained in this State is derived by separation from the gold, which always contains more or less of it as an alloy-the amount procured from this source not being large. Thus, it will be seen, silver is not a leading, but rather an incidental product of California mining; and the metallurgical treatment of its ores, though of vital importance in the adjoining State of Nevada, is of little practical moment in California.

GOLD.

Among the mineral products of California, gold is incomparably the most important metal. Rapid and immense as has been the development of this branch of mining in California, it is yet, in view of future results, scarcely more than barely entered upon, the repositories of this form of wealth remaining comparatively intact. Gold, with rare exceptions, is found in the native or metallic state. It is never, however, perfectly pure, being always alloyed with more or less silver, and sometimes also with small quantities of platinum, copper, iron, mercury, palladium, iridium, rhodium, etc. It also occurs in a mineralized condition in

connection with other metals combined with tellurium. The minerals, sylvanite and nagyagite, are examples of this mode of occurrence; and other compounds of the same class, whose characteristics are as yet but imperfectly known, have been found at Carson Hill, in Calaveras county, at the Rawhide Ranch Mine in Tuolumne county, and at a few other localities in the State. But these telluric compounds of gold, though rich in this precious metal, are of rare occurrence, and possess no general interest. It has been a matter of doubt with some, whether the gold present in auriferous pyrites, mispickel, etc., existed in the metallic state or mineralized in combination with sulphur. The prevalent opinion among the best chemists being that in these ores the gold is always in the metallic state, though its mechanical subdivision is in this case almost chemically minute-it will here be assumed that such is the fact. The metallurgy of gold is thus entirely confined to the separation or extraction chiefly, though not entirely, by mechanical means, of the native metal from the earthy débris or the rocky gangue, which may accompany or contain it.

In the consideration of native gold, our attention is first drawn to the fact that it occurs extensively in two distinct and well characterized conditions. It is found either in the solid rock, usually in veins, whose gangue is almost universally quartz, accompanied by various metallic oxides and sulphurets; or else it is found in alluvial deposits, in the form of minute scales, pellets, coarser grains, or larger pieces, always more or less water worn, and mixed with the sand and gravelly debris of all sorts of rocks, whose degradation and comminution have been the slow work of ages preceding the advent of man. To the latter class of deposits the general name of placers has been given, and from these two prominent modes of occurrence have arisen two distinct modes of mining, viz: placer, and quartz, or vein mining.

PLACER MINING.

The placers themselves may be again subdivided into two prominent classes, the deep and the shallow; or, speaking generally, the ancient and the modern placers. In California, these deposits, particularly the shallow placers, are also frequently styled "diggings," and these have again been further characterized according to their topographical position, as river, gulch, bar, flat, bench, and hill diggings; while the deeper placers have been called hydraulic diggings, tunnel diggings, etc., according to their situation, and the means adopted for their exploitation. At first operations were almost entirely confined to the

shallow or surface diggings, which owe their origin in great measure to the denudation and degradation, by mountain streams, of the older and deeper detrital formations-enormous quantities of the earthy and lighter materials having been washed away, while the gold has been left in a concentrated form and in positions readily accessible to the miner. Many of these shallow diggings, exceedingly rich when first discovered, having long since become either exhausted or greatly impoverished, are now almost wholly abandoned to the Chinese.

The methods and implements employed in placer mining, and by means of which such immense quantities of the precious metal were once extracted, seem insignificant compared with those now in use. In all placer mining the gold is obtained by washing the auriferous gravel, the sand and earthy matter being carried off by a current of water, while the gold, owing to its vastly greater specific gravity, remains behind, and can then be collected by itself in the metallic state or amalgamated by means of mercury.

THE SHALLOW PLACERS.

The principal implements employed in shallow placer mining are the pick and shovel, horn spoon, pan, cradle or rocker, long tom, and the sluice. The horn spoon is made by a lateral section cut from the horn of an ox, which, being scraped thin, forms a sort of curved spoon, from one to two inches in depth, two to three inches in breadth, and six to ten inches long. This spoon is used exclusively for "prospecting purposes"—that is, for testing the richness of auriferous gravel or pulverized rock, by washing in it small quantities at a time. In its use some skill is required, especially when, as is often the case, the gold dust is very fine, to save and exhibit as nearly as possible the whole of the precious metal present. This spoon holds at most but two or three pounds of earth, and it might seem that tests so rudely made could be of little value. It is found, however, to answer this purpose better than might be expected; and it is surprizing how closely an experienced prospector will estimate the probable yield of rock or gravel, after having made a sufficient number of trials with it to enable him to approximate an average of the mass.

The pan in present use is usually stamped from thin sheet iron, possessing the advantages of lightness and strength, while at the same time it is not attacked by the mercury often used. In shape and size, this implement resembles an ordinary circular dairy pan, with a twelve or fourteen inch bottom, the chief difference consisting in its having a more flaring form. In using this pan, it is first filled with the aurifer

ous earth, which is then taken to a stream, puddle, or tub of water near at hand, for washing. Being submerged, if the material be clayey in texture, it is worked over with the hands till it becomes disintegrated, and then the washing commences. One side of the pan being held a little higher than the other, by a peculiar circular motion of the hands a revolving current is produced within it, which carries away the lighter portions over its top, while the heavier matters remain behind. In this way the earthy particles are gradually washed away, the pebbles being removed by the hand, until nothing is left but the gold, either entirely clean, or mixed with a small quantity of heavy sand. The residue thus obtained is either saved until more has been accumulated, and then, if necessary, carefully washed as clean as possible, or it is amalgamated with a little mercury. With the pan, as well as the horn spoon, it requires practice and skill to wash rapidly and well. In the earlier days of mining the operation of washing for gold was mostly performed by the pan. It rapidly gave place, however, to the cradle, the long tom, and the sluice, and is now very rarely used, except for mere prospecting purposes. It is also indispensable in the "cleaning up" of sluices, and also about quartz mills, as a means of washing and saving small portions of amalgam.

The cradle and the long tom, as successors of the pan, were improvements on the latter as means for extracting gold-each in its day being the most efficient implement known for that purpose. Both, however, were superseded by the sluice, and can now be rarely seen, except where used occasionally by the Chinese, for which reason a particular description of them is here omitted.

The sluice, in its various forms, is now the apparatus generally employed for separating the gold from the worthless matters with which it is mixed, in both the deep and the shallow placers. In form and dimensions it varies to suit the work for which it is intended, being in some cases but a few feet long, while in others, especially in hydraulic mining, its length reaches several thousand feet. The sluice is essentially a long, slightly inclined trough, through which a rapid stream of water flows, the bottom being provided with a suitable arrangement for catching and retaining the heavier particles, while the lighter are carried forward and discharged with the water at its lower end. In its ordinary form as applied to shallow placers, it consists of a series of wooden troughs open at the ends, each being from ten to twelve inches deep, from fifteen to twenty inches wide, and twelve feet long. They are constructed of rough pine boards, from an inch to an inch and a half thick, and are made three or four inches narrower at

one end, so as to fit into each other, and thus form a continuous sluice of any desired length.. By this arrangement they can be rapidly put together, and as readily taken down and removed. The sluice is set to a uniform grade, so that the fall in each twelve feet, or the length of a box, is from ten to eighteen inches, according to the character and quantity of the material to be washed. If the fall in twelve feet be ten inches the sluice is said to have a ten-inch grade. Across the bottom. of each box is nailed a number of cleats called riffles, intended to catch and retain the gold and amalgam. As these riffles and the bottom of the sluice itself would soon be worn out if left unprotected, by the stones. and gravel passing over them, a set of false riffles, consisting of a frame of slats, is placed longitudinally in each box, presenting the necessary cavities for catching and holding the gold, while its surface is such as to present the least possible resistance to the stones and gravel passing over it.

The most common style of riffle in sluices for shallow placers, is formed of strips of plank two or three inches thick, from three to six inches wide, and about five feet six inches long, being nearly half the length of a single box. These strips are placed on edge, an inch or two apart, side by side, longitudinally along the bottom of the box, being properly wedged to keep them in place. There is thus formed a series of narrow rectangular depressions, having a depth equal to the width of the strips, and which, though quickly filled with sand when the sluicing is commenced, still present a sufficient number of cavities and inequalities to retain the particles of gold, while the pebbles are carried smoothly forward by the current of water. When, however, as often happens, the gravel to be washed contains large quantities of stones, the wear upon the riffles, even with the best arrangement, is severe, necessitating frequent renewal. To meet this emergency, instead of the riffles described, the sluice is paved with blocks of wood cut crosswise the grain, and placed with the fibres in a vertical position on its bottom, narrow spaces being left between the blocks which fill with sand and serve to retain the gold. These block riffles are not only durable, but very efficient in saving the amalgam and gold. If the placer gold dust were always course the riffle would be a complete and all-sufficient means of saving it. But, since this is not the case, the grains being of all sizes, from nuggets several pounds in weight down to an almost impalpable powder, so fine that when dry it will readily float upon the surface of the water; or if suspended in it, be carried along by the gentlest current; the use of mercury in the sluice becomes necessary to arrest and save these minute particles, which even this agent, with its strong