Precious metals deposits of Nevada

The Nevada Bureau of Mines and Geology (NBMG) has developed a database of
known precious metal deposits in Nevada reported in the post-1930 literature. Among
the data included, when reported, are resources, reserves, production, deposit type,
host rock, Au/Ag ratio, age of mineralization, and references. The deposits were plotted
on 7.5-minute topographic maps from the best available information, and the locations
were then measured in UTMs. The data were entered into a dBase-compatible
database, which is amenable to a number of GIS programs. An original gold endowment
was calculated for many of the deposits using the available reserve, resource,
and production data. A series of maps is produced to demonstrate the usefulness of
these data. Maps plotting deposit type and deposit type/host rock show the usual distribution
with the bulk of the Carlin-type deposits confined to the northeastern third
of the state and the vein and stockwork type deposits more scattered but mostly concentrated
in the western part of the state. These maps show the usual Carlin-type
deposit trends—Carlin, Getchell, Independence, and Battle Mountain-Eureka. They
also show other apparent trends such as a north-south trend of the Bald Mountain,
Alligator Ridge, and Yankee sediment-hosted gold deposits, a north-south trend of
mostly medium to large epithermal deposits between Goldfield and Round Mountain,
and an east-west trend of mostly small epithermal deposits across central Mineral
County. Most of the deposits are older than the Walker Lane right-lateral strike-slip
displacement and Basin and Range extension, suggesting some of the present-day
trends may change if these features were factored out. The maps show that sedimenthosted
deposits are more concentrated in the eastern part of the state, as would be
expected because the east is predominantly sedimentary and west is predominantly
volcanic. Six out of eight of the over-10-million-ounce gold deposits are Carlin-type
deposits and seven of the deposits are located on the Carlin, Getchell, and Battle
Mountain-Eureka trends. The remaining one is the volcanic-hosted Round Mountain
deposit. Although important in their time, none of the pre-1930 districts, such as the
silver-gold deposits of the Comstock Lode and Tonopah and gold-silver deposits of
Goldfield, individually yielded as much as 10 million ounces of gold. Total silver production
from the Comstock and Tonopah, however, make these major districts even
by today’s standards.