An underground copper mine located near Calumet, MI. The Tamarack Mining Co. was organized in 1882 in the hopes of profiting from the rich Calumet Conglomerate that made C&H millions of dollars. Work was started on a vertical shaft and in 1885 at a depth of 2,270 ft., the lode was intersected. Four more shafts were driven, all vertical, during the development stage. The deepest, shaft #5, intersected the lode at 4,662 ft. and was bottomed out at 5,309 ft. from the surface. The mine worked at a profit from 1887 to 1907. In 1917, Tamarack sold the property to Calumet & Hecla for $3 million, and the company was dissolved. In 35 years of operation, Tamarack produced 389,215,899 lbs. of refined copper, making Tamarack the second largest producer from the Calumet Conglomerate. A wide range of minerals can be found here, including copper, silver, cuprite, malachite, powellite, and copper "skulls".
Source: Mindat.[url]http://www.mindat.org/loc-23692.html[/url] />
For the mystery see:
[url]http://www.lhup.edu/~dsimanek/hollow/tamarack.htm[/url]