Deep-sea vents and ore deposits
Part of Hall of Planet Earth.
Some ore deposits now exposed on land originally formed in the oceans. Metals dissolve in seawater when it flows through and reacts with hot rock. When hot, metal-laden water spews from vents and mixes with the cold ocean, the metals precipitate. Large piles of sulfide accumulate on the seafloor and are eventually buried by sediments, modified by heat and pressure in the crust, and uplifted. Some are exposed on land when erosion removes the overlying rocks.
