Mystery error camouflaged among the obvious expected results from a misaligned tilted die strike

Collectors' Clearinghouse: Faint beads in Ethiopian coin’s unstruck quadrant cry out for explanation
By , Special to Coin World
Published : 09/27/16
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Some of the most interesting errors also happen to be ones that are faint, subtle, or camouflaged.

A deliciously stealthy mystery is found on a 1931 Ethiopia 25-matonas coin. It shows two obvious die alignment errors — a hammer (reverse) die that was horizontally misaligned and strongly tilted. These two errors often go together because when a die tilts down it also tends to swing in, unless there is compensatory movement in the opposite direction. In this case the hammer die shifted toward the southeast and tilted down in the northwest. The hammer die’s elevated pole failed to contact the southeast quadrant of the reverse face and left unstruck the corresponding southwest quadrant of the obverse face (a consequence of being struck in “medal rotation”). The planchet was properly centered over the anvil die.

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Surprisingly, the southwest quadrant of the obverse face — which faced the anvil die — is not entirely design-free. It displays two faint, closely spaced rows of raised beads that roughly parallel the coin’s edge and that are located approximately 3.5 millimeters in from that edge. The inner row has nine beads while the outer row has four. Like a set of parentheses, the curved line of beads lies directly across from the unstruck crescent on the opposite face produced by the misalignment.

The size and shape of the beads corresponds to those normally present just inside the obverse design rim. The obverse beads are slightly larger than those on the reverse, as shown in a normal comparison example.

It’s clear that before, during, or after the strike, the unstruck southwest quadrant of the coin’s obverse face contacted the periphery of the anvil die while the planchet was in an off-center position. It’s not clear what provided the necessary resistance to the impact of the anvil die. It stands to reason that any impact strong enough to leave an impression would presumably require an equal and opposite force (Newton’s third law of motion).

Over the years this column has presented an array of errors that manage to sidestep this requirement without actually violating Newtonian physics. These errors include extrusions strikes, stutter strikes (three types), rim-restricted design duplication, and ejection impact doubling. But none of the conditions associated with these errors is present in the example under discussion.

The first step in our investigation is to see what the physical evidence tells us about the circumstances surrounding this error.

Since the planchet was centered during the primary strike and off-center when the extra beads were generated, it’s highly unlikely that a single downstroke was responsible for every design element. The isolated beads must therefore have been generated before or after the main strike.

The double row of beads implies either two closely spaced strikes or a single jittery strike. It’s also possible that the beads were impressed without the benefit of a downstroke at all. After all, there are other means by which a planchet can make contact with a die (e.g., ejection impact doubling).

The two rows of beads are short and fade out at their ends. This strongly suggests that the impact or impacts were delivered at an angle. If a tilted hammer die was responsible, its downward-tilted pole would have pointed toward the southeast quadrant of the reverse face — a direction exactly opposite that of the tilted die error.

If the hammer die was inclined in this fashion, then it may have been blocked by a second planchet overlying the planchet represented by our featured coin. One would also have to assume that the hammer die was not horizontally misaligned to any significant degree, since the more medially positioned letters would have struck up instead of the beads.

Previous columns have documented rapid die oscillations (side-to-side movements), rapid changes in die angulation, and rapid changes in striking pressure. If the above scenario is correct, it would imply that the double row of beads was generated while minimum die clearance had momentarily increased to the thickness of two planchets.

In the end, we will never be sure what happened.

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