From the early 1900's and until the 1940's, the Terlingua Mining District was the third largest mercury producing area in the United States. The mercury was produced from an ore called cinnabar. Cinnabar was first discovered in the Terlingua area in the 1880's. However, it took until the early 1900's for the mining of the cinnabar and the production of mercury to expand and become full scale operations. Hard to believe, but at one time, Terlingua had a population of 2,000 to 3,000!
Cinnabar is reddish in color and is mercury sulfide. The mercury is produced by heating the ore at about 360 F at which point the mercury and sulfur will separate and vaporize. The vapors were cooled until the mercury condensed out and was bottled. The sulfur vapors (probably SO2, SO3) escaped into the air (probably causing a rather foul odor in the area).
Even today, you can see evidence of the mining and of the furnaces in the area from Study Butte to Lajitas. Mines such as the Chisos Mining Company (the company store is now the store at Terlingua), the Rainbow Mine, Lone Star, Little 38, Marfa and Mariposa Mine, Colquitt Tigner and Lone Star Mine all operated in the area from Study Butte to Tres Cuevas Mountain (just outside Lajitas).
When we were in Big Bend in 2003, we took a side trip to see the mine at Study Butte. The mine was filled in and we could not find the mine shaft, but did see the furnaces. The old furnaces were built in the early 1900's. You can see where the pipes that carried the mercury vapor and sulfur vapors went up the side of the mountain to the condensors. In the late 1960's, Diamond Shamrock reopened the mine and installed a rotary furnace; that operation shut down in the early 1970's.
There are a couple of great books on the mining in the area. Kenneth Ragsdale's book "Quicksilver: Terlingua and the Chisos Mining Company" and C. A. Hawley's "Life Along the Border" are great reading and tell of the history of the area.
