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Mining Techniques

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Gold miners arrived in California with varied degrees of preparedness. Some miners arrived with virtually no tools, attempting to use spoons, handkerchiefs, pots, and bowls to obtain the precious metal. Some Chinese gold miners discovered that the wok was a surprisingly effective gold pan. Most of the rest purchased their tools as ruinous rates. Collis P. Huntington, who after a half a day in the diggings abandoned mining for business, made a minor fortune buying shovels at $2.50 a dozen, and having cornered the market, selling them for upwards of $125 a dozen. As President of the Southern Pacific Railroad, his freight rates demonstrated the understanding of the brutal law of supply and demand he gained in the gold fields. Yet not all Argonauts were naïve to the art of mining. Amid the thousands of amateurs were a handful of knowledgeable professionals. Many were Welsh and Cornish miners from the tin mines of Britain, along with many Mexicans experienced in gold mining. A few Americans were veterans of the Georgian gold mines. One such Georgian, Isac Humphrey, is credited with introducing the gold pan and rocker in 1848 (Paul, 52). The pan was the simplest means for extracting gold from the sediments in which it resided. A miner would take a shovelful of "pay dirt" and place in the pan. Picking out the stones and pebbles, he would place the pan beneath the water and swirl it until the lighter sands and silts had been washed off into the rivers, leaving behind the denser gold dust. It was a slow and tedious means of mining, as even the most patient and experienced miner might only wash 15 pans per hour. It was also excruciatingly difficult labor, as the miner had to hunch in the freezing water while his back baked in the sun, painfully discovering the existence of muscles he was unaware he had.

The next development, the rocker, allowed a miner or a team of miners to sift through a significantly larger volume of auriferous sediments. It consisted of an open box with a screen to catch pebbles, leading down to a short riffled trough. A miner would shovel sediments down into the boxes, while another poured water over. A third man then rocked the cradle back and forth, causing the lighter sediments to be washed over, while the denser gold was trapped in the riffles. A great deal of finer gold passed over the riffles and was lost, but because of the increased amount of sediments thus processed, use of a rocker was significantly more profitable than use of a pan. Furthermore, it reduced some of the tedium, as men in a group could alternate tasks.

In late 1849 a new invention appeared, the Long Tom. It consisted of a box with a grating, built over a ten-foot riffle platform. A stream was diverted to rush over the platform, while paydirt was shoveled into the box and washed down the riffles. The running water eliminated the rocker’s tedious labor of rocking and pouring. By 1851, the long riffle box of the long tom had been expanded into a network of sluices, running often for hundreds of feet. Such sluices, bottomed with riffles, captured most of the gold dust within the paydirt. Woolen blankets were sometimes placed at the end to grab onto the finest particles. Sluices however took significant cooperation and modest capital to build, and frequently twenty men went into business together to construct a sluice network.

Another cooperative, but highly risky, mining technique was to build a diversion dam, looking for alluvial gold at the bottom of a streambed. However, it was usually impossible to determine where alluvial deposits were situated until after the dam had been constructed and stream diverted, making diversion dams a highly speculative enterprise. Even if there was gold, the miners gambled on the weather, for heavy rains might burst their crude dam and force them to wait until the next season to attempt recovery.

When miners engaged in a cooperative mining endeavor, they invariably formed a company. Instead of committing capital, however, most miners committed their labor, agreeing to work on the project for so many hours per week in return for a share in the profits. By 1851, the independent miner with his pan and rocker was increasingly a thing of the past as miners had to band together as the placer reserves were increasinly depleted.

The gold dust recovered from pans and riffles was not pure. Often it was mixed with black sand that had a density similar to gold. The crudest techniques, introduced by Mexican miners, were to use air to blow off the slightly lighter sand. A miner might either hold a pile of dust on his palm and gently blow it, or he might place a large quantity on a blanket and with the help of companions fling it into the wind, catching the gold while the sand was blown off. Both techniques resulted in the significant loss of finer particles. The more sophisticated method of using mercury (a.k.a. quicksilver) soon spread across the mines. Mercury, a liquid metal, forms an amalgam with gold. The mercury can then be separated from the gold by boiling, with the mercury vapors captured and condensed for reuse. The discovery of quicksilver in San Jose in 1836 ensured that a ready and convenient source of mercury already existed in the state.

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