Hydrothermal mineralization is ubiquitous and one of the primary ore-forming processes on Earth. Knowledge of the dissolution, transport, and precipitation of ore-forming metals at elevated temperatures and pressures is requisite for an unambiguous understanding of hydrothermal mineralization processes and metal deposit formation. Traditionally, studies on fluid-rock interaction, fluid inclusions, element or mineral solubility, and aqueous metal speciation have provided abundant information on ore-forming processes. As a result, many thermodynamic properties for important metals in aqueous solutions under hydrothermal conditions, as well as their geochemical behavior, have been successfully determined through empirical and semiempirical extrapolation methods, further enriching our views on metal speciation in hydrothermal processes and also providing a continual updating on our understanding of the formation of important metal deposits.

Recent advances in high-temperature and high-pressure technology, combined with the development of experimental methods and pertinent analysis techniques, have considerably helped improve our knowledge about ore-forming metals and fluids under hydrothermal conditions. In particular, new studies on synthesized or natural fluid inclusions via in situ analysis of laser-ablation ICPMS and utilization of the visual hydrothermal cell, hydrothermal diamond-anvil cell, and fused silica capillary reactors, combined with UV-Vis spectrophotometry, Raman spectroscopy, and synchrotron techniques, have demonstrated a broad research perspective on hydrothermal processes.

The purpose of this special issue is to publish high-quality research papers as well as review articles that seek to address recent advances on hydrothermal processes and metal mineral ore deposits. Particular interest will be given to papers exploring or discussing metal solubility, speciation, migration, and precipitation in hydrothermal fluids. Original, unpublished, high-quality contributions that are not currently under review by any other journals or peer-reviewed conferences are welcome.

Potential topics include but are not limited to the following:

• Dissolution, transport, and precipitation of metals by fluids
• Metal complexation, speciation, and stabilities of metal complexes in fluids
• Hydrothermal growth and solubility of minerals
• Fluid reaction and metasomatism of minerals or rocks
• Thermodynamic properties of terrestrial or submarine hydrothermal fluids, basinal brines, and metamorphic/metasomatic fluids or magmatic fluids
• New technology and methods on studies of hydrothermal mineralization