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The Atlantic to the Pacific: What to See and How to See it (1873), by John Erastus Lester


Quartz Mining in California and Colorado.

Quartz Mining in California and Colorado.—In Colorado quartz mining has almost entirely superseded placer and hydraulic mining. In California however, hydraulic-mining is still carried on upon a gigantic scale in some sections, where vast sums of money have been expended in bringing a supply of water to the claim. Placer-mining was the earliest mode in which the loose gold was removed from the surface-soil by means of the inexpensive rocker, pan, &c. Hydraulic-mining is placer-mining on a gigantic scale; and, while the first mode is but little practised now, the latter is carried on, in many localities, at a profit. On the road to the Yo-Semite, you will find Chinamen at work with those early inplements, rocker, pan, &c.; and from the Central Pacific Railroad, at Gold Run, you can see an example of hydraulic-mining in the valley below the road. Quartz-mining is now, however, the general mode of obtaining gold. Many veins or leads where former owners have lost vast sums of money are now, under new and more economical management, paying largely. All through the mountains of California, and in Colorado, Nevada, Utah, Montana, &c., are great stamp-mills pounding out the gold from the rock. The rock, in these States—pure quartz, through which is mingled gold and silver—is blasted out, and is run through a crusher, which reduces it to small pieces. Then it goes to the ‘stamps.’ For these water must be had in abundance, and is generally brought in a flume into the mill, where it empties into the ore-trough, and is conducted out through a race. There is a heavy frame-work of timber, and long, upright sticks, to the end of which a heavy iron face is attached; which sticks are made to work up and down in guides. A shaft—upon which are cam-pulleys, or, generally, merely a bar inserted through the shaft—is made to revolve by means of steam or water power, and, by the cam-motion, raises the stamps; and, letting go, the stamp falls with force to the bottom of the box. The box extends the whole width of the framework, and into it is shovelled the crushed ore and the stamps pound away upon the stone and dirt in the water, which is made thick and muddy. On the side of the box towards the race are holes along the whole length, out of which the muddy water flows into a gutter, which carries it to a spout in the middle, from which it runs into the race. There are large copper plates which cover the bottom of the race. Upon them is spread a thin coating of quicksilver, which takes up the gold as the water flows over it. There are several of these plates, which are placed one after the other down the race; and at the end of the last is a blanket, made of wool, and through which the water flows. When it is thought that the quicksilver has absorbed all the gold that it will take, the plate is removed, and the amalgam is scraped off, and a fresh coating of quicksilver is put on. Occasionally the blanket is rinsed out in a tub of water, which is poured back again into the box. The gold is taken from the amalgam by subliming the quicksilver, as before described.

There are some stamps where the quicksilver is

Yosemite Valley map, 1972
[click to enlarge]
PLAN OF YO-SEMITE VALLEY
placed in the box in liquid form, and the whole mass of ore, water, and quicksilver, is agitated until an amalgam is formed. By this process water is saved—a desideratum in some localities.

I saw a stamp-mill just like the one above described at Black Hawk, in operation upon ore composed of quartz and gold and silver. But a majority of the Colorado ores cannot be worked in this manner at all; for if the sulphides of iron or copper are present, then a very different process must be resorted to. Here lay the cause of failure of so many mining enterprises in Colorado. In California, they say that professors and students have always failed as miners, and that only practical miners have been successful. But here it was a professor, trained in a college laboratory, who found out by patient toil and study just what was required, and brought success out of a seeming ruin. At the Boston and Colorado Smelting Works, at the head of which is Professor Hill, you can see the ores of Colorado successfully reduced. The ores from the mines are purchased by samples, which are nicely assayed, and the value per ton thus determined. The ores are then placed in large heaps, in form of a pyramid, over a loose pile of fire-wood. A match is applied; and, as the mass becomes heated, the sulphur is set free and burns out. This process is called roasting; and the sulphur supplies fuel for some three months in piles of the usual size. In making up a pile, the coarse is packed first, and over the outside the fine ore is covered. When the ore is freed from the sulphur, it is crushed, and is smelted in a furnace in a similar manner to iron ore. The product is a matte, which is composed of iron, copper, gold, and silver. In this form it is transported to Swansea, Wales, where the final reduction takes place.

Large works are being built at Georgetown, and others projected at Golden, to deal with these ores; and if they succeed, the mining-interests of Colorado will brighten, and those Eastern people, who now have only a stock-certificate to show, may not, after all, have made so poor an investment when they invested in a gold-mine.

Here ends the story of my journeyings. I trust my writing has not been amiss; for I have had before me continually one aim—to give only correct information that would aid my readers in planning a trip from the Atlantic to the Pacific, that they might know what to see, and how to see it.



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