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Mine drainage is formed when pyrite, an iron sulfide, is
exposed and reacts with air and water to form sulfuric
acid and dissolved iron. Some or all of this iron can
precipitate to form the red, orange, or yellow sediments
in the bottom of streams containing mine drainage. The
acid runoff further dissolves heavy metals such as copper,
lead, mercury into ground or surface water. The rate and
degree by which acid-mine drainage proceeds can be
increased by the action of certain bacteria. |
