Deep-shaft mining is much like mining for any other mineral. Typically, the salt exists as
deposits in ancient underground seabed‟s, which became buried through tectonic changes over
thousands of years. Many salt mines use the "room and pillar" system of mining.. After the salt is
removed and crushed, a conveyor belt hauls it to the surface. Most salt produced this way is used
as rock salt. Mined salt varies very widely in composition, depending upon the locality but
normally above 95%. Some rock salt, however, runs as high as 99.55 pure.