Gold Districts of California
Bulletin 193 California Division of Mines and Geology 1976
Table of Contents
This district is in the vicinity of the old mining town of Coloma in western El Dorado County. It is on the South Fork of the American River about eight miles northwest of Placerville.
Although this is a relatively small district, it is significant, for it was here that James W. Marshall made his historic gold discovery. In August 1847, Captain John Sutter, grantee of a large Mexican land grant in the vicinity of present-day Sacramento, signed a contract with Marshall to erect a sawmill on the American River. Work commenced in September 1847. The mill was almost finished on January 24, 1848, when Marshall, inspecting the mill tailrace, noted several small flakes of what appeared to be gold. Work on the mill stopped, and more flakes were recovered. These were taken to Sutter at Sacramento for more tests, which proved beyond a doubt that it was gold. Attempts were made to keep the discovery a secret, but the news quickly leaked Out.
Soon Sonorans from the Los Angeles placer-mining districts arrived, the vanguard of the thousands of gold seekers who came from all directions to Coloma. The surface placers here were soon exhausted, and the miners went elsewhere. Coloma was named for a nearby Southern Maidu Indian Village. Early spellings were "Colluma" and "Culoma". Some gold dredging was done on the American River here during the 1930s and 1940s.
Marshall never was associated with a really successful mining venture and died in 1885 in the nearby town of Kelsey, a poor man. The Marshall Monument, where he is buried, was dedicated in 1890. Part of the old town, the mill site and the monument joined the California state park system in 1927. A replica of Sutter's mill was recently constructed at the park. Also at the park is a museum containing many items of early-day mining equipment.
Geology and ore deposits
The central portion of the district is underlain by a granodiorite intrusion. It is surrounded by slate, mica schist, amphibolite, and several north-trending lenticular bodies of serpentine.
Most of the gold values were obtained from gravels in the American River or from terrace gravels along the bank. A few narrow gold-quartz veins crop out and several contact-metamorphic copper-gold deposits are found along the margin of the granodiorite.
Clark, W. B., and Carlson, D. W., 1956, El Dorodo County, gold: California Jour. Mines and Geology, vol. 52, pp. 400--437.
Lindgren, Waldemar, and Turner, H. W., 1894, Placerville folio, California: U. S. Geol. Survey Geol. Atlas of the U.S., folio 3, 3 pp.
Cutter, Donald W., 1948, The discovery of gold in California: California Div. Mines Bull. 141, pp. 13-17.
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