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spark-erosion die: used to strike counterfeit coins, these dies are made by placing a steel cylinder close to an actual coin, then arcing electricity between the two to create a nearly perfect duplicate (in reverse) of the coin.
spark-erosion die A die made by an electrolytic deposition method. The surfaces of such a die are very rough, so they usually are extensively polished to remove the Â"pimples.
 See also: Surfaces, Large size, Liberty Seated, Lincoln cent, Medium letters
  
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