The eastern part of the Monte Cristo Range, in Esmeralda County, Nev., has been prospected for many years, and one mine, the Carrie, was developed as early as 1890. The discovery of high-grade ore by the Gilbert brothers on the Last Hope claim in 1924 led to a boom during which the region was extensively prospected and claims were staked out covering not only the Gilbert district but another area from which the barren later andesite has been eroded, known as South Gilbert. The total production for the years 1917-1925, according to data furnished by Mr. V. C. Heikes, U. S. Bureau of Mines, amounted to $24,807, about two-thirds of which was from gold.