Located near Salida Colorado this mine is a premier source of some of the better Epidote crystals to about 2" found in North America. It was originally mined long ago for iron ore by CF&I (Colorado Fuel and Iron) Steel of Pueblo Colorado, which at least when I took a high school field trip in 1975 was still the largest steel producer west of the Mississippi. The Calumet Mine has also produced massive magnetite, actinolite, blue corundum, pryrite, and fine gem grade quartz some included with epidote or chlorite, among other minerals. The blue corundum is the only occurence of note that has been elusive for me, though I have found some small nail head sized pieces. It is not difficult to find plenty of interesting specimens to take home with you at the Calumet Iron Mine, though if you want to find the best this location has to offer, be prepared to do some hard rock mining. There is nothing quite like opening up a new pocket of great mineral specimens that have never been seen before.