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<p>[QUOTE=&quot;RonSanderson, post: 8156898, member: 77413&quot;]Another thread that I read yesterday has some pictures of coins with rim burrs. The planchet itself might have a rough edge from being punched out of the original sheet of metal. When it runs through the upsetting mill and gets its edge, that excess metal burr is nearly sheared off, but not fully detached. Edit: That loose burr can pick up the shape of the reeding if it is in the right position in the die collar during striking.</p><p><br /></p><p>This looks a bit like that shape, but of course it is not at the edge of the coin. But if the prior coin had excess metal at the edge that became detached during final stamping and fell into the die, then it could have been stamped into this coin and leave a depression.</p><p><br /></p><p>An interesting feature of the example in the other thread was that the rim burr had a corrugated shape because it had the shape of the reeded edge. If a rim burr had that shape, then was twisted, you could get a spiral shape to the strike-through. (Does the spacing of the ridges inside this depression match the spacing on the reeding?)</p><p><br /></p><p>While I favor the explanation above, there are actually three good candidates for the cause.</p><p><br /></p><p>1. A planchet flaw. This would be a crack or fissure from rolling out the metal, or even a dent from another planchet when the coins are washed and dried in a drum-like piece of equipment. During striking, the metal will try to fill up this dent by forcing up from below and from the sides. Because the metal flow is constrained by being in the die, it won’t come above the surface of the coin.</p><p><br /></p><p>You can usually find examples of this all over coins under magnification. Almost all Jefferson nickels show this effect on his shoulder and cheek. Here’s a cent planchet to show that this roughness is quite pronounced.</p><p><br /></p><p>[ATTACH=full]1423375[/ATTACH]</p><p><br /></p><p>2. A gouge. Since this happens after the coin is out of the die, the displaced metal will have to go somewhere. It will cause a lump that protrudes above the surface of the coin, which is a good indication it could not have happened inside the die.</p><p><br /></p><p>3. A strikethrough. Again, being inside the die, the metal cannot have a ridge that rises above the surface.</p><p><br /></p><p>If you see any metal that is displaced above the surface of the coin, it has to be PMD. That just can’t happen with the die pressing down on it.[/QUOTE]</p><p><br /></p>

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