sentences:  These ore bodies tend to be compact, fairly uniform plug-like or pipe-like replacements of their host carbonate sequences and as such can be extremely profitable mines.This classification of ore deposits is also known as Mississippi Valley Type or "MVT" ore deposits, after a number of such deposits along the Mississippi River in the United States, where such ores were first recognised; these include the famed Southeast Missouri Lead District of southeastern Missouri, and deposits in northeast Iowa, southwest Wisconsin, and northwest Illinois.Similarly Irish-type carbonate lead-zinc ores, exemplified by Lisheen Mine in County Tipperary, are formed in similar ways.