The man with pick, and pan, and rocker required but little capital for the prosecution of his enterprise; but mining in the quartz rock requires money to conduct it. Shafts must be sunk, and levels must be driven; the ore must be raised to the surface, the rock must be pulverized, and the gold extracted; and the machinery to accomplish this is more or less elaborate, and always costly. The mines are worked in the same way as other underground mines. The shafts, the levels, the tunnels, are the same; but after the ore is raised, there is a great expense attending its reduction. The rock must be broken, and placed in pulverizing machines, and after it is crushed, whether by rollers or stamps, the gold must be separated.
CATCHING GOLD WITH QUICKSILVER.
The water which carries away the gold is made to flow where it comes in contact with quicksilver placed along a series of riffles. In many instances blankets are spread, over which the water flows; and as the gold comes in contact with the rough surface of these blankets, it is caught and held.
Some of the gold miners in California invented a table of amalgamated copper, on which quicksilver was spread, and the ore coming in contact with it was stopped.
There are other inventions for the same purpose. In one the pulverized ore is agitated in a bath of quicksilver, and in another an inclined trough is divided into compartments filled with quicksilver, in which a series of forks have an oscillating movement, to bring the sands in contact with the fluid metal as they flow through the troughs. Sometimes sheep-skins are used inside of blankets, so that the golden fleece can be considered an affair of modern times, as well as of the earliest days of ship-building.
In working the placer mines by the hydraulic process, the miner can manage with profit the dirt which contains only a millionth part of gold.
In the quartz mining, the proportion of gold ought naturally to be greater, since it is necessary to execute all the work, which is partly done at the placers by nature; that is, to dig, transport, pulverize, enrich the ore, and finally amalgamate it.
In California the quartz ores of least hardness cannot be worked profitably when they yield less than five dollars’ worth of gold to the ton, or about one hundred thousandth proportion. Quicksilver is mainly employed in the auriferous quartz ores. When the gold of the placer is very fine, and invisible to the eye, or the work is done by means of long channels, riffles filled with quicksilver are placed in the bed of the stream, which detain all the gold in its passage, no matter how small the particles. The scales of gold which come in contact with this fluid are instantly caught up, and no process has yet been invented which can supersede that of quicksilver.
SUGAR CANDY OF A GOLD MINE.
The amalgam obtained in this way is generally liquid, but it is allowed to take up sufficient gold to give it the consistency of paste. It is passed through a chamois-skin folded into a bag, and twisted like a piece of wet linen. The quicksilver, being separated from the gold, passes through the pores of the skin in the form of silver drops, and is caught in a basin beneath. The gold must now be separated from the paste, and the amalgam left behind resembles a ball of tin. Quicksilver dissolves gold just as water dissolves sugar, but the quicksilver can be driven away in vapor, and the gold will remain. The amalgam can be made to give up its gold in the same way that a solution of sugar and water can be made to yield sugar candy. In this way gold may be considered the sugar candy of the miner.