This district is in east-central Butte County about 15 miles northeast of Oroville. It is fairly extensive and includes the Concow and Big Bend areas.
The streams and surface placers were first worked during the gold rush. For a time the locality was known as Rich Gulch and Spanishtown. In those days much gold was recovered from the North Fork of the Feather River, and a diversion tunnel was driven through Big Bend. Numerous Chinese miners reworked the old placer tailings later on. Lode mining began in the 1850s, and there was much activity during the 1890s and early 1900s. The Surcease mine was worked on a major scale from 1933 to 1942, and copper was mined at the nearby Big Bend mine during World War II. The estimated output of the district is slightly more than 100,000 ounces of gold.
A northwest-trending belt of slate and quartzite four to five miles wide, with some limestone that is part of the Calaveras Formation (Carboniferous to Permian), crops out in the central part of the district. Interbeds of amphibolite and serpentine lie to the north. Granodiorite stocks are to the east and southeast.
A number of quartz veins contain some free gold and often abundant sulfides, especially chalcopyrite. The veins are in the metamorphic rocks. Milling ore commonly averages 1/2 ounce of gold per ton, much of the values being in the sulfides. The Surcease vein has been mined to a depth of more than 1000 feet. A gold-bearing barite vein occurs at the Pinkston mine.
Berry Creek, Bunker Hill, Evening Star, Hearst, Madre de Oro, Pinkston, Porter, Rainbow, Sunbeam, Surcease $1 million+, Treasure Hill.
Logan, C. A., 1930, Butte County, gold quartz mines: California Div. Mines Rept. 26, pp. 369-383.
Miner, J. A., 1890, Butte County, quartz mines and mills; California Min. Bur. Rept. 10, pp. 125-133.
O'Brien, J.C., 1949, Butte County, gold: California Jour. Mines and Geology, vol. 45, pp. 426-433.
Turner, H. W., 1898, Bidwell Bar folio: U. S. Geol. Survey Geol. Atlas of the U.S., folio 43, 6 pp.