In different parts of the world the term epithermal is commonly used for a variety of deposit styles. Using the redox state of
the ore-forming fluid (inferred from mineralogy and alteration), the metal assemblage of deposits, and other characteristics,
at least five different styles of epithermal deposit can be distinguished. Most of these different deposit styles appear to be
related to magmatic fluids, with differences resulting from different compositions of source magmas. The most common
style of epithermal deposit (low-sulfidation gold-silver deposits associated with calc-alkaline volcanic rocks) remains the
most difficult to explain; the metals in these deposits may be derived by basement leaching without magmatic input, or they
may come from magmatic volatiles, with contaminated I-type or S-type magmas as the most likely source.