One of the early groups of mines working in Ontonagon County, the American Mining Company was based in Windsor, Vermont and had a variety of mines throughout the US  These four in the Copper Country were their most profitable.
The Norwich and the Windsor were on adjoining property and together held over 300 acres of land.  A stamp mill with 8 heads, many buildings and a hoisting engine were all built on the property and these 2 mines together worked well through the mid-1860s.
The Derby and Sharon mines were situated about 1-4 miles from the Norwich and were worked for many years also.
These mines, especially the Sharon, were referenced in the collection of stories titled "Early Days of the Lake Superior Copper Country" by Orrin W. Robinson.