By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Placer County, noted chiefly for its placer mines, has also produced substantial lode gold particularly from the Ophir district. Gold was discovered in 1848 in Auburn Ravine. In the 1850's, bars in the American River and its tributaries were worked, and quartz mining also began. In the- Foresthill Divide area, Tertiary channels were mined by drifts, and in the Dutch Flat-Gold Run, Iowa Hill, and Yankee Jim districts, gold was extracted from gravels by hydraulic methods. The Michigan Bluff placers have also been productive.
The center of lode mining in Placer County is the Ophir district. Gold-quartz mines were active in the Canada Hill district (Logan, 1936, p. 10), but production from this area could not be ascertained. Logan (1936) described the gold deposits of this county and was the chief source of information for the production and description of the districts. Total production for the county from 1880 through 1959 was about 2,014,000 ounces.
DUTCH FLAT-GOLD RUN DISTRICT
The Dutch Flat-Gold Run district is along the north boundary of Placer County on the system of Tertiary channel deposits that extends south from Nevada County.
Placer mining began in 1849, and by 1857 hydraulic and drift mines were producing on a fairly large scale. Though early records are almost nonexistent, it was estimated (Logan, 1936, p. 58, 65-70) that the district produced about 479,000 ounces of gold to 1935. In recent years, because of high costs and restrictive legislation, production has decreased to less than 1,000 ounces per year. Total production through 1959 was about 492,000 ounces.
FORESTHILL DISTRICT The Foresthill district is in south-central Placer County. Foresthill Divide is a complex system of Tertiary channels capped by lavas. The gravels have been extensively worked by drift mines which reached their peak of productivity in the 1860's (Logan, 1936, p. 49). Before 1868 the Independence, New Jersey, and Jenny Lind mines produced $2,400,000 in gold. Estimates of production of individual mines given by Logan (1936, p. 51-80) give a minimum total for the district of about 338,000 ounces of gold. In recent years, the district has been virtually dormant. Total gold production through 1959 was about 344,000 ounces.
IOWA HILL DISTRICT The Iowa Hill district is about 5 miles east of the town of Colfax. Thick Tertiary gravels have been worked by hydraulic and drift mines in this district (Lindgren, 1911, p. 148-149). The Morning Star mine, with a production worth $1,750,000 to 1901, was the largest of the drift mines (Logan, 1936, p. 71). Total production of this district to 1910 was about $10 million (Lindgren, 1911, p. 149). No activity has been reported in the area since before 1932, except in 1958 when about 300 ounces was produced.
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