By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Boulder County, in north-central Colorado along the east side of the Front Range, ranks ninth among the gold-producing counties of Colorado. Its west boundary is the Continental Divide; its eastern part includes a small area of the Great Plains. All the metal-mining camps are in the mountainous western part. Gold is the chief metal produced in the county, but considerable silver and tungsten and small amounts of lead and copper have also been produced. Through 1959, Boulder County was credited with an output of about 1,048,200 ounces of gold; all but about 3,000 ounces was from lode mines.
Discoveries of gold deposits in Boulder County, which date from 1858 (Henderson, 1926, p. 38, 105-106), were among the first in the State. Though placers were worked first, most of the gold mined before 1869 was from oxidized free-milling lode ore, and when this was depleted, many mines closed. Through 1868 the annual production was less than $50,000 in gold. The construction of a new smelter at Blackhawk in 1868 stimulated activity in the mining camps, new veins were discovered, and mines and camps developed rapidly. Gold production increased from about $100,000 (4,838 ounces) in 1870 to $683,941 (33,089 ounces) in 1891 and to a peak production of $982,988 (47,556 ounces) in 1892 (Henderson, 1926, p. 106). After the panic of 1893, when the price of silver dropped, gold production fluctuated but generally declined; only $16,516 (799 ounces) in gold was produced in 1930. The rise in the price of gold in 1934 stimulated gold mining, and 33,621 ounces was produced in 1940. Activity again declined during World War II and decreased even more after the war.
Boulder County has many mining camps and districts, but to 1959 only five had a total gold output in excess of 10,000 ounces: Jamestown (Central), Gold Hill-Sugarloaf, Ward, Magnolia, and Grand Island-Caribou.
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