The mining practice that uses solutions to extract a desired commodity from an ore deposit where it stands without also extracting the rock is known as solution mining. There are essentially two types of solution mining: 1) in-situ and 2) in-place. In-place solution mining requires permeability enhancement techniques such as blasting or previous mining activities (i.e. block-caving) to fragment or increase the permeability of the rock prior to applying a leaching solution to liberate ore from the surrounding ore body. In-situ methods rely solely on the naturally occurring permeability of the ores. Copper as well as a number of other commodities are harvested by solution mining methods. Water-soluble salts such as potash (sylvite), rock salt (halite), thenardite (sodium sulfate) and nahcolite (sodium bicarbonate) are commonly derived from massive sedimentary deposits by in-situ methods. Most of the sulfur produced in the Gulf of Mexico region is recovered by a solution mining method, known as the Frasch process, which injects superheated water to melt the sulfur so it can be pumped to the surface (Christensen et. al., 1991). Approximately ninety percent of the uranium mined in the United States is also recovered by solution mining methods.