Quartz is very hard rock and once removed from the earth has to be crushed in a stamp mill. Beginning in 1898 the Feather River was dredged with thousands of cubic yards processed per day and over 20 million ounces of gold produced.ĭespite all the efforts at removing gold from hillsides, rivers, creeks and floodplains the greatest amount of gold was produced from hard rock mining of quartz veins. The miners dredged these areas and could profit if the sediment contained only $0.10-0.15 cents of gold per cubic yard of sediment. These areas had fine sediments with highly distributed gold deposits. The next focus of the gold mining companies were the valley rivers and floodplains. In 1884 Judge Sawyer outlawed hydraulic mining in the Yuba River and the practice stopped in the state.
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The flood of 1877-78 inundated many cities and farms and initiated a series of lawsuits between downstream owners and the mining companies.
The destruction of numerous mountainsides washed millions of yards of sediment into Central Valley rivers and the San Francisco Bay filling channels and affecting adjacent farmland. Nearly every stream and reservoir in the Sierras has remnant mercury in its sediments. The mining and processing of quicksilver in furnaces as well as its use in the gold fields has left a major toxic legacy. Mercury was mined in the coastal ranges of California in places like New Almaden (Santa Clara County), New Idria (San Benito County) and many mines in Lake, Napa and Sonoma Counties. Mercury has a natural attraction to gold and will amalgamate the small flecks into larger amalgams which are then heated to remove the mercury. To collect the gold flecks in the gravels and wash water the miners added mercury or quicksilver. Between 18 over 11 million ounces of gold were produced using hydraulic mining. By 1865 5,000 miles of ditches and flumes had been constructed to move water to the hydraulic mines. Water had to be developed and transported through ditches or canals to the mining site. Many hundreds of cubic yards of sediments could be processed in a few hours. Termed hydraulic mining, large monitors or hoses were aimed at hillsides and washed away the sediment so it could be sorted and the gold in the ancient riverbeds could be mined. Instead of indivduals or small groups of miners, investment companies using expensive equipment started mining using large volumes of water. In 1853 gold mining changed significantly. Nearly every alluvial creek channel was dewatered, sorted for gold and left today many waterways show the remnants of this mining.
Between 1848-1853 about 10-12 million ounces of gold were produced. Several cubic yards of river gravels could be sorted per day this way. When miners first started looking for gold they used simple techniques for sorting river gravels with a metal pan or a rocker or long tom. The foothills have recovered significantly from the ravages of the gold rush through both natural restorative processes and the work of farmers and ranchers. The Sierra Foothills have a beautiful pastoral landscape of oak woodlands, grazing lands, orchards and vineyards, river canyons and creeks.
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