Mariscal Mine, a remote cinnabar mining district on Mariscal Mountain in what is now Big Bend National Park, was developed to refine ore into mercury and produced about 1,400 flasks over its operating life, a notable share of the nation’s output in the first half of the 20th century. Discovered in 1900, it passed through several owners as mercury prices shifted, with major periods of activity under W. K. Ellis, the Mariscal Mining Company, and a brief failed revival in 1942–1944. Today its ruins spread across 640 acres, preserving industrial remains and the harsh history of mostly Mexican miners who endured low pay, long hours, company-store dependence, and mercury-related illness.