Abstract: Described herein is a system and method for hydrothermal mineral extraction wherein the conditions surrounding hydrothermal systems are used advantageously to extract a mineral-rich brine. Specifically, hydrothermal fluid from ocean based or saline based hydrothermal systems contain a variety of minerals suspended in supercritical water and can be drawn up a well. As long as the water remains a supercritical fluid, the minerals remain largely in solution; however, as the hydrothermal fluid moves away from the this state, the water can cool and exit the supercritical state, causing the depositing or scaling of minerals along the walls of the well pipe. In the instant invention, non-supercritical conditions are rapidly induced onto the hydrothermal fluid such that the brine containing the minerals rapidly precipitates and forms a slurry which is then isolated from the water. Another aspect regards altering the chemistry of the fluid to precipitate the minerals.