The Jessie was one of the largest mine and mill complexes in the Breckenridge area, with as many as seven mine openings on the hillside leading into a vast underground network. During its heyday from the late 1880s through the early 1900s, hardy miners used drilling and blasting techniques originally developed in Cornwall, England. Men hauled blasted ore to the surface and transported it by a gravity-powered cable tramway from the Glenwood tunnel to the stamp mill. Built in 1893-94, the stamp mill crushed large chunks of run-of-mine ore into sand-sized particles using 800-pound, piston-like iron stamps moving up and down. Today, only the wooden shafts that housed the stamps and storage bins remain.