Hydrothermal alteration is a geological process that occurs when hot water interacts with rocks, resulting in mineralogical and chemical changes. This process typically takes place in the Earth's crust, where fluids are heated by magma or other geothermal heat sources. The interaction between the hot water and rocks can lead to the formation of new minerals and changes in the physical properties of the rocks. Hydrothermal alteration is commonly associated with ore deposits, as it can concentrate and enrich certain metals within the altered rocks. Studying hydrothermal alteration can provide valuable insights into the processes occurring within the Earth's crust and can help geologists identify potential mineral deposits.