Formation of Anhydrous and Hydrous Skarn in Cu-Au Ore Deposits by Magmatic Fluids

Most skarn ore deposits are characterized by two distinctly different alteration styles. An early prograde stage with anhydrous minerals, such as garnet and pyroxene, forms from relatively high-temperature, hypersaline liquid. A later retrograde stage with hydrous minerals, such as epidote, amphibole, and chlorite plus sulfide ore minerals, forms from lower temperature, lower salinity fluids. These two alteration stages commonly have been...