Error coins and other imperfections

Last updated: 18 January 2009

Contents of this page

  1. Introduction
  2. Types of errors
  3. Examples

1. Introduction

All ancient coins are imperfect in some way especially if compared to modern coins. Despite the primitive minting techniques used throughout the ancient and medieval periods, expectations towards the product varied widely both in artistic and technical terms - just comapare the brilliant silver pieces of the heights of the Hellenistic age with late Roman coins, Byzantine coppers or early medieval pieces.

If the quality control procedure does not work well substandard pieces may leave the mint. These are the error coins (mint errors). One can find many other technical imperfections among ancient coins, some of them will be discussed here, too.

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2. Types of errors
  1. Flan problems
    • Wrong metal, size, shape or texture
    • The flan cracks during stiking
  2. Flatstrike: the upper die was not held vertically. The coin is wedge-shaped: one side is thicker than the other and the images become shallower towards this part.
  3. Off-flan: the flan was not centered over the lower die (parts of the obverse are off-flan) or the upper die did not struck the flan in the centre (parts of the revese are off-flan); can occur together.
  4. Double strike: During multiple blows, the die doesn't hit the coin on exactly the same place resulting in double-countour images. Can be partial or total; affecting only one side or both sides.
  5. Overstrike:This is not really an error, mainly coin struck on an existing coin. On purpose using old coins to produce new ones and save the flan preparation procedure. The original devices main remain identifiable.
  6. Brockage (incuse): One side of the coin (usually the obverse) is of normal appearance; the other one is a mirror image of the same device impressed in the flan. A readily struck piece is stuck to the upper die without being noticed and a new flan is placed on the lower die and struck. This time the the upper die is eventually a coin from the previous strike. The result is the brockage.

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3. Examples

  1. Coin doublestruck on both sides

    Xenon-Pyrba double strike

    This coin is doublestruck on both sides: a freshly struck coin was put again on the lower die flipped, and was struck again. Traces of the images from the previous strike are visible on the opposite side, respectively.

  2. Brockage

    Antimahos brockage

    On the left we see the obverse of a cow-calf/type drachm, cow to right, eagle on fulmen above, name: Antimahos. The other side shows the exact mirror image of the obverse in incuse. Brockages occur in any coinages; but here two conclusions can be drawn regarding the Greek-Illyrian coinage:

    • Several other examples prove that the cow-calf device formed the lower die of the drachms; brockages cannot be expected showing the image of the upper die (at least I have never seen a reverse brockage in the Ilyrian coins).
    • Despite one can see only the obverse of the drachm, the name on the reverse is also identifiable! The symbols on the obverse are determined by the name on the reverse. Antimahos with eagle on fulmen above is known only with Damageos reverse, from Dyrrhachium. Therefore the coin shown is an Antimahos-Damageos drachm; Dyrrhachium Class 4; C 72; SBG Cop 461.

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