By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Gold was discovered in Calaveras County in 1849 in gravels along Carson Creek, a tributary of the Stanislaus River. In 1850, rich lode deposits were found above the placer diggings on Carson Hill, where a single nugget from the outcrop was valued at more than $40,000 (Julihn and Horton, 1938, p. 12). Many methods of placer mining have been utilized in working the Quaternary deposits in this county: hand rocking, sluicing, hydraulicking, dredging, and dragline operations. The rich auriferous channel gravels of the Tertiary Calaveras River and the Cataract or Table Mountain channel have been mined by drifts. Most of the production from 1880 through 1959 was from lode mines in the Mother Lode, East Belt, and West Belt districts.
There is no record of production before 1880, when mining of the rich placers was at its peak, but Julihn and Horton (1938, p. 21) estimated that the placers yielded a minimum of $50 million (about 2,415,000 ounces) in gold in the early years. From 1880 through 1959, a total of 580,600 ounces of gold was mined from placer deposits, and 2,045,700 ounces, from the siliceous ores of the Mother Lode, East Belt, and West Belt. Production since 1950 decreased sharply; in 1959 the county produced only 167 ounces of gold.
The Mother Lode, East Belt, and West Belt districts have produced nearly all the lode gold reported from Calaveras County. Copper ores in the Campo Seco district have yielded a relatively small amount of gold. Important placer localities are along the channel systems of the Tertiary Calaveras River and the Tertiary Table Mountain channel, and Quaternary gravels have been highly productive at Jenny Lind and Camanche.
The Camanche district is in northwest Calaveras County, near the Mokelumne River.
Gold was recovered, by bucket-type dredges and draglines, from late Tertiary or early Quaternary gravels, some of which are in the flood plain of the Mokelumne River. Production is not known, but 100,000 to 1 million ounces is estimated.
CAMPO SECO DISTRICT
The Campo Seco district, in Tps. 4 and 5 N., R. 10 E., in northwestern Calaveras County, has yielded gold from Quaternary gravels of the Mokelumne River and also as a byproduct of copper ores.
Most of the placer mining was before 1900, and the amount of gold produced in those early operations cannot be estimated. Most of the byproduct gold was from the Pern mine, which operated from 1899 to 1919 (Julihn and Horton, 1938, p. 112).
During that time an estimated 800,000 tons of ore was mined which contained 0.03 to 0.10 ounce of gold per ton, or a total of 40,000 to 50,000 ounces. The mine was inactive until 1937, when the workings were unwatered, and copper was recovered from the mine water. Significant amounts of gold were produced during the 1940's, but after World War II when the demand for copper ceased, the mine became dormant. Total gold production of the district was about 60,000 ounces.
The geology of the area was discussed briefly by Julihn and Horton (1938, p. 112-113). The ore bodies are massive sulfide replacement bodies in zones of amphibole schist and sericitized greenstone. The ore consists of an intimate mixture of fine-grained pyrite, chalcopyrite, and sphalerite, and smaller quantities of bornite and tetrahedrite.
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