Layered deposits containing varying amounts of pyrite, copper, lead and zinc sulfide minerals, along with baryte. Commonly, also gold and silver.
VMS deposits form when hot fluids circulate through rocks of the seafloor, dissolving various metals, and then come into contact with cold seawater, causing the metals to precipitate as piles of tiny mineral grains. VMS ores are often located near “black smokers”, jets of superheated water shooting from the ocean floor. Some ancient VMS deposits are today found on continents or islands, having been lifted from the seafloor by tectonic action. Examples include Japan’s Kuroko deposits, Norway’s Folldal deposits and British Columbia’s Sullivan ores