This is the original survey map of 1902 of the U.S.Geological Survey, (survey details on the link above.)
Terlingua is shown
at the base of California Mt. (now called California Hill), which was the village of the Mariposa
Mine. Titles of Mountains or Buttes are shown in similar type, and mines are listed as mines.
Here, just of interest, Study Butte is shown as a Butte, not a mine. Compare the type to Bee, Willow, Leon,etc.
At the time of this printing, the mine at Study Butte,the Big Bend and Texas Almaden Mine,
was just gearing up to produce quicksilver, and began production the following year, 1903 (see handbook of Texas on Line
http://www.tsha.utexas.edu/handbook/online/articles/view/MM/dkm2.html. William Study, however, was the Post Master at the Mariposa Mine
(Terlingua,Tx P.O.) during the time this map was being published. In 1904, the P.O. at the Big
Bend and Texas Almaden Mine was called Bigbend, Texas, and thePost Office called Study Butte, Tx did
not begin till 1917.