定義

• Brockage.  In the broadest sense, an imperfectly struck numismatic item; specifically brockage is a multiple planchet error which occurs when a struck piece does not eject, a fresh blank is brought into position between two coining dies, and the two pieces are struck as one blank. In effect the interface surface of the struck piece acts as a die (since the struck piece became work hardened by the striking it is harder than the fresh blank). It gives the newly positioned blank a negative impression of the die it receives on the opposite side. In other words the blank will have two obverse strikes – or two reverse strikes – one will be negative and one positive.
  Brockage pieces are usually centered on both sides; infrequently the second blank does not fully enter into coining position and will not be centered (while the first piece is centered). Both sides uncentered is very rare.
  If the struck piece continues to stick to the die (called hanging up), and not eject, it may produce a cupping (or capping) effect as a malfunction.  See mis-struck. A brockage piece might be mistaken for a hub trial or a signet medal (with a total incuse design on one side) but these are generally uniface and not all that common.
  References:                                                                                                                                
  NE42  {1982} Doty, p 37-38. 
  NM19 {1991} Margolis, p 233-238.

  excerpted with permission from

  An Encyclopedia of Coin and Medal Technology

  For Artists, Makers, Collectors and Curators

  COMPILED AND WRITTEN BY D. WAYNE JOHNSON

  Roger W. Burdette, Editor

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