Mississippi Valley-type deposits, commonly referred to as MVTs, are hydrothermal lead-zinc ore deposits that are characterized by (1) low-temperature formation (50[degrees]-200[degrees]C, but usually 100[degrees]-150[degrees]C), (2) epigenetic (forming after) emplacement within restricted dolstone or limestone strata of sedimentary basins (i.e., stratigraphically controlled), (3) precipitation from highly saline brines, and (4) the presence of barite and/or fluorite gangue ...