Hittel on Gold Mines and Mining

HITTEL ON GOLD MINES AND MINING
Chief Industry. —Mining is the chief industry of California. It employs more men and pays larger average wages than any other branch of physical labor. Although it has been gradually decreasing in the amount of its production, in the profits to the individuals engaged in it, and in its relative importance in the business of the state, it is yet and will long continue to be the largest source of our wealth, and the basis to support the other kinds of occupation.
Metals obtained. —Our mines now wrought are of gold, silver, quicksilver, copper and coal. Ores of tin, lead, and antimony in large veins, beds of sulphur, alum and asphaltum; lakes of borax and springs of sulphate of magnesia, are also found in the state, but they are not wrought at the present time, though they will probably all become valuable in a few years. Platinum, iridium, and osmium are obtained with the gold in some of the placer mines, but are never found alone, nor are they ever the main object sought by the miner. The annual yield of our gold mines is about forty millions of dollars, of our quicksilver two millions of dollars. Our silver, copper and coal mines have been opened within a year, and their value is yet unknown. All our other mining is of little importance as compared with the gold.
Gold Mines. —Our gold mines are divided into placer and quartz. In the former, the metal is found imbedded in layers of earthy matter, such as clay, sand and gravel; in the latter it is incased in veins of rock. The methods of mining must be adapted to the size of the particles of gold, and the nature of the material in which they are found. In placer mining, the earthy matter containing the gold, called the pay-dirt, is washed in water, which dissolves the clay and carries it off in solution, and the current sweeps away the sand, gravel and stones, while the gold, by reason of the higher specific gravity, remains in the channel or is caught with quicksilver. In quartz mining the auriferous rock is ground to a very fine powder, the gold in which is caught in quicksilver, or on the rough surface of a blanket, over which the fine material is borne by a stream of water. About two-thirds of our gold is obtained from the placers, and one-third from the quartz.