Over the past three decades, a large number of seafloor hydrothermal vent sites and associated sulfide deposits have been discovered in the worlds' oceans. Geochemical analysis of samples collected from vent sites worldwide suggests that seafloor sulfide deposits may contain significant base and precious metal concentrations. The present study provides the first estimate of the global rare metal endowment of these deposits. It is shown that seafloor sulfide accumulations can contain elevated concentrations of the rare elements Bi, Cd, Ga, Ge, Hg, In, Mo, Sb, Se, Te, and Tl. Although these polymetallic deposits may represent a significant repository for some of these elements, the total endowment is regarded to be limited when compared to land-based ore deposits. Potential future deep-sea mining will not likely be a significant source of these metals
