The name "Eagle Mining Company" is sufficiently popular and general that it is difficult to precisely pinpoint the exact location of the firm. John J. Ford, Jr. advises that in the 1860s and 1870s at least two companies operated under this name in Gilpin County, Colorado.
The Mines of Colorado, 1867, notes of the Eagle Mining Company:
They have a first-class fifty-stamp mill at the mouth of Gamble Gulch. The building is 75 X 90 feet, contains the batteries, plates, sixty-horse engine and boilers, and that is all. It was run through June, 1865, but without paying result. It was shut up and is likely to remain so until further developments in the art of treating Colorado ores - The Company has a boarding-house, barn, and other necessary buildings near their mill on South Boulder.
Another possibility is that the following items may have been from ore taken from the "Eagle" claim in Lake Gulch, Gilpin County.
An offering of a $103.00 gold ingot in Stack's Gibson Collection Sale (1974) contained information furnished by John J Ford, Jr.:
Ten dated and four undated gold Eagle Mining Company ingots are known. The former dated 1875 (1), 1877 (3), 1878 (5), and 1879 (1), together with a somewhat larger number of silver ones. The first of these appeared on the market over twenty years ago, apparently from a small group in Arizona. Over the years, additional examples have occasionally turned up. For instance, a gem dealer and western enthusiast from Roxbury, Connecticut, named R.C. Romanella, found two gold ingots in Central City, Colorado in 1965. (One of these was the Gibson Collection example). At least three of the fourteen gold "Eagle" ingots are stamped COL. The fourteen different pieces can be broken down into four or five separate groups, differing either in shape, style, date, or numerical sequence, or punch arrangement, or a combination of these characteristics. To further complicate matters, rumor has permeated the research done to date to the effect that the company either removed to Arizona Territory or else that a key employee or associate absconded with the assaying equipment and issued ingots bearing the firm's stamp in Arizona Territory. This is confirmed by an advertisement in the Numismatic Scrapbook Magazine, June 20, 1954, under the name of R. Green, in which a $50 gold ingot of the Eagle Mining Company was offered, claiming it was made by the Eagle Mining Company of Eagle City, Arizona. The advertisement noted that "This company used gold from Planet and other mines in Cieniga Mining district about sixteen miles above Park and five or six miles below the mouth of Bill Williams fork in Yuma County, Arizona."
