This district is in northwestern Plumas County. It is an extensive area that lies between Lake Almanor on the north and the Virgilia-Twain area on the south and southwest. The district includes the Caribou and Seneca areas. The Crescent Mills district is just to the east, and the Meadow Valley district lies to the south.
During the gold rush vaSt amOunts of placer gold were recovered from the Feather River and its tributaries. The valley was named for Horace Butts, a successful early-day miner. The town of Seneca was an important center at that time. The Butt Valley Reservoir was constructed by the Great Western Power Company in 1921. Lode-gold mining, which originally began in the 1850s, continued through the 1930s. Since then there has been intermittent prospecting at a few properties such as the Sunnyside mine. Skin divers and weekend prospectors have been active along the streams.
The district is underlain by a series of metamorphosed sediments ranging from Silurian to Triassic in age. Slate is most abundant, but also present are sandstone, limestone, Quartzite, and conglomerates. In addition, there are greenstones and serpentine.
The gold-quartz veins occur in brecciated zones in all of the formations, but they are most abundant in the slates and greenstones. The ore contains free gold and varying amounts of sulfides, including arsenopyrite. Milling ore averaged usually only a few dollars per ton, but the ore bodies were extensive. Some of the veins and vein zones are 20 or morc feet thick. An appreciable number of high-grade pockets were found. In places the placer deposits, both Tertiary and Recent in age, were extremely rich.
Lode: Chico Star, Dean, Del Monte, Duncan, Elizabeth Cons., Halstead, Hazzard, Horseshoe, Justice, Lictum, Plumas Amalgamated, Reising, Rich Gulch Cons., Savercool, Seneca Cons., Shenandoah, Summit, Virgilia, White Lily $225,000+
Placer: Barker Hill, Cameron $100,000+, Dominion, Ellis, Lot, Providence Hill, Red Rock, Sunnyside $150,000+, Swiss, Dutch Hill $575,000+
Averill, Charles V., 1937, Plumas County, gold: California Div. Mines Rept. 33, pp. 103-124.
Logan, C. A., 1928, Plumas County, gold: California Div. Mines and Mining, Rept. 24, pp. 285-310.
MacBoyle, Errol, 1920, Plumas County, Butt Valley district: California Min. Bur. Rept. 16, pp. 1-4.