text:  The Bureau of Land Management ( BLM ) administers most land in the Trout Creek Mountains , but there are also some private lands and some roads in the area . The private lands are mainly used for ranching along mountain streams , while the BLM lands include large grazing allotments for local ranchers ' cattle . At least 100 mining claims in the mountains have been recorded since 1892 , some of which were staked for gold exploration . Commercial mining has occurred in some areas , mostly near the <unk> Caldera , where uranium and large amounts of mercury have been extracted . Mines in what was called the <unk> Mining District produced 270 @,@ 000 flasks of mercury — " the richest supply of mercury in the western hemisphere " — from cinnabar extracted from the caldera in the 20th century . The two leading mercury @-@ producing mines in North America were the Cordero and <unk> mines on the edge of the caldera in Nevada . Together , they operated from 1933 to 1989 . The <unk> Mine , the last mercury mine in the United States , closed three years later , in 1992 . However , mineral exploration has continued at the Cordero Mine in the 21st century , and waste containing mercury and arsenic was returned there from the community of <unk> as part of a U.S. Environmental Protection Agency cleanup project . 
  