5.50 oz Chico Ledge Exhibition Ingot From the Chico Ledge. 

5.50 ounces, 991 fine, $7.05. Chico Ledge, Echo District, Humboldt County, NT, circa 1863. There are three different mines carrying the Chico name in the western U.S. through about 1873. One is in Arizona, and another in New Mexico, but both are principally gold mines. The only silver mine with the Chico name is a fairly well known silver mine or prospect in the Unionville area, near the Star and Buena Vista districts. The Echo mining district contained approximately 75 different lodes in 1863-1865, second only to the Humboldt district located nearby.
The Humboldt area was one of the most remote mining districts in Nevada Territory and in the west in general. It is so remote that Unionville and Star City, the two major mining camps that housed up to 1000 miners and prospectors at one time, was never canvassed by any of the early directory companies. Sam Clemens was there in 1861-1862, and staked several claims with his brother and friends. His hilarious stories about the area can be read in Roughing It, published in 1871, under his pen name, Mark Twain.
The Chico was a prospect once owned by John Bidwell, a California pioneer who came to California in 1841 and went to work for John Sutter. He became Brigadier General of the California Militia in 1863, and founded Chico, California.
This ingot was most likely an exhibition ingot used in conjunction with high grade ore specimens from the mine. Both were probably shown off in San Francisco in about 1863, a common practice for companies incorporated there (as was the Chico) who were trying to raise money. The lack of an Internal Revenue tax stamp indicates an early period of manufacture before the bullion tax law was emplaced.
From The Kagin Reference Collection of Frontier Ingots.

[8/2006] https://coins.ha.com/itm/ingots/chico-ledge-exhibition-ingot-from-the-chico-ledge-550-ounces-991-fine-705-chico-ledge-echo-district-humboldt-county/a/414-2570.s ($9,200)

[10/2010] https://www.icollector.com/Humboldt-County-NV-c1863-Chico-Ledge-Exhibition-Silver-Ingot-5-50-ozs-Territorial_i9800046

[08/2012] https://www.icollector.com/Chico-Ledge-Exhibition-Silver-Ingot-NV-Humboldt-County-c1863-2012aug-Numismatic_i13391246 ($11,950)