Arsenide systems form in continental rifts where deep-seated, oxidized, metal-rich, metamorphic basement brines ascend to shallow levels. Native elements (Ag, Bi, As), Ni-, Co- and Fe-mono-, di and sulf-arsenides precipitate by reduction as hydrocarbons, graphite, or sulfide minerals are oxidized to form carbonates and barite.
Color on map:

Deposit types

Name Commodities Critical minerals
Five element veins Ag, As, Co, Ni, Bi, U, Sb Co, Bi, U, As, Sb


Source: Hofstra, A.H., and Kreiner, D.C., 2020, Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative: U.S. Geological Survey Open-File Report 2020-1042, 24 p.,

List of Earth MRI focus areas with mineral system = Arsenide

2 focus areas match these criteria.

Focus area Region States Mineral Systems Deposit types Commodities
Black Hawk Mining District Southwest New Mexico Arsenide Five element veins copper; gold; silver; uranium
Black Rock district—Monte Cristo mine Southwest Arizona Arsenide Five element veins copper; gold; silver; uranium