By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
The gold-quartz mines of the Grass Valley-Nevada City district in Nevada County have been the most productive in the State, and the Empire mine in the same district was in continuous operation from 1850 to 1940, which at that time was the longest period of operation for any gold mine in the country (Logan, 1941, p. 375). Placer production has also been significant, especially in the early days; however, no consistent records have been kept. Tertiary gravels on San Juan Ridge, North Columbia, Sailor Flat, Blue Tent, Scotts Flat, Quaker Hill, and Red Dog-You Bet still contain tremendous reserves, but these are for the most part undeveloped because of the curtailment of hydraulic mining.
The total gold production of the county from 1849 through 1959 was 17,016,000 ounces, including Lindgren's (1896, p. 26) estimate of $133,800,000 in gold. Since 1903, when placer and lode production have been reported separately by the U.S. Geological Survey (1904-24) and U.S. Bureau of Mines (1925-34, 1933-66), 286,655 ounces of placer and 7,119,353 ounces of lode gold have been mined in the county.
GRASS VALLEY-NEVADA CITY DISTRICT
Because the towns of Grass Valley and Nevada City, which form the center of the Grass Valley-Nevada City district, are only 4 miles apart and because of their similarity in geology, distribution and mineralogy of veins, and common history and development, they are discussed together.
The initial rush to this area took place in 1850 after rich gravels were discovered near the present site of Nevada City. In October of the same year, the first lode discovery was made at Gold Hill on the outskirts of Grass Valley (Johnston, 1940, p. 19). Almost immediately the towns of Grass Valley and Nevada City were founded; they grew rapidly, prospered, and became permanent communities.
By 1851 quartz mines had been developed at Nevada City, but these early ventures failed. The miners turned to working the rich Tertiary gravels on a large scale by introducing hydraulic methods (Lindgren, 1896, p. 19). The discovery at Gold Hill was followed by discoveries of veins at Ophir Hill, Rich Hill, and Massachusetts Hill, and by 1867 most of the major mines of the district had been located. Grass Valley, where 1,600 men were working and 284 stamps were crushing the ore, was then one of the leading camps in California (Johnston,1940, p. 19). Meanwhile new discoveries of lode deposits were made at Nevada City, and quartz mining became dominant there after 1880. Some of the important mines at Nevada City are the ChamÂ¬pion, Providence, Canada Hill, Hoge, and Nevada City. The Empire, North Star, and Idaho-Maryland mines have accounted for more than two-thirds of the production of Grass Valley and have exerted considerable influence on the economic life of the community. Indeed, in 1938 and 1939 the Idaho-Maryland had the largest gold output of any mine in the State. In recent years activity has declined in the district, and in 1957-58 most of the production was from cleanup operations at the Empire and North Star mines.
Production of the Grass Valley-Nevada City district is difficult to determine accurately because of the incompleteness of the early records. Of the estimated $113 million worth of production from 1849 to 1893, at least 60 percent was credited to the lode mines (Lindgren, 1896, p. 28). From 1903 through 1958, Nevada County produced 7,119,353 ounces of lode gold and 286,655 ounces of placer gold. Almost all of the lode gold is assumed to have come from the Grass Valley-Nevada City district. Converting Lindgren's estimate to ounces, the total production of the district through 1959 was approximately 10,408,000 ounces of lode gold and 2,200,000 ounces of placer gold.
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