Silver was discovered at Sheridan around 1897. The mine was located in Sheridan mining district of Okanogan County. (also known by the Phil Sheridan mine) Between 1906 and 1919 shipments of high grade silver/gold ore were made to smelters. Around 1914 a mill was built at Sheridan. The mill and operations did not prove to be profitable. In 1917 Sheridan all but ceased mining operations, although ore shipments were made up until 1920. The Sheridan Mine produced between $60,000 and $100,000 of silver in its time.
One rumor surfaced that the Sheridan Mine had been named for Lieutenant Phil Sheridan. This rumor was based on Sheridan's travel through the vicinity around 1880. There is nothing that can substaniate this rumor however.