These fluids are referred to as hydrothermal and the deposits they form as hydrothermal mineral deposits. As a family hydrothermal mineral deposits form when a hot, aqueous solution (dominantly composed of hot water) flows through permeable units in a restricted portion of the earth’s crust and precipite a localized mass of minerals from its dissolved load. Just how hydrothermal solutions form, how they react with the rocks through which they pass, and how they deposit their carried constituents are topics of interest to economic geology.