Describe the formation of mineral deposits at hydrothermal vents

Hydrothermal vents form where cold seawater percolates down into the Earth's oceanic crust, and is superheated by the geothermal gradient. Under the confining pressure of the surrounding rock and the overlying water, it can reach temperatures in excess of 400 ° C. As the water is heated, the pressure it is subjected to increases and it begins to rise to the seabed. In doing so, the superheated fluid dissolves minerals from the surrounding rock and carries them to the surface in solution. When it reaches the surface, it comes into contact with seawater at around 2 ° C; this drop in temperature causes minerals to precipitate from the hydrothermal fluid. These precipitates may develop as structures surrounding the vents and fissures in the rock, at the point of contact between the two temperature extremes. They may also form as particulates, and be dispersed by currents and turbulence around the location of the hydrothermal vent. The density of minerals affects where they are deposited; denser minerals are transported shorter distances.